Keithley 7172 Service manual

Model 7172Low Current 8 × 12 Matrix Card

Instruction Manual

A GREATER MEASURE OF CONFIDENCE

W ARRANTY

Keithley Instruments, Inc. warrants this product to be free from defects in material and workmanship for a period of 1 year
from date of shipment.

Keithley Instruments, Inc. warrants the following items for 90 days from the date of shipment: probes, cables, rechargeable
batteries, diskettes, and documentation.

During the warranty period, we will, at our option, either repair or replace any product that proves to be defective.

To exercise this warranty, write or call your local Keithley representative, or contact Keithley headquarters in Cle veland, Ohio.
You will be given prompt assistance and return instructions. Send the product, transportation prepaid, to the indicated service
facility . Repairs will be made and the product returned, transportation prepaid. Repaired or replaced products are warranted for
the balance of the original warranty period, or at least 90 days.

LIMIT A TION OF W ARRANTY

This warranty does not apply to defects resulting from product modification without Keithley’s express written consent, or
misuse of any product or part. This warranty also does not apply to fuses, software, non-rechargeable batteries, damage from
battery leakage, or problems arising from normal wear or failure to follow instructions.

THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING ANY
IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. THE REMEDIES PRO­VIDED HEREIN ARE BUYER’S SOLE AND EXCLUSIVE REMEDIES.

NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT,
INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS
INSTRUMENTS AND SOFTWARE EVEN IF KEITHLEY INSTRUMENTS, INC., HAS BEEN ADVISED IN ADVANCE
OF THE POSSIBILITY OF SUCH DAMAGES. SUCH EXCLUDED DAMAGES SHALL INCLUDE, BUT ARE NOT LIM­ITED TO: COSTS OF REMOVAL AND INSTALLATION, LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY
PERSON, OR DAMAGE TO PROPERTY.

Keithley Instruments, Inc.

Sales Offices: BELGIUM: Bergensesteenweg 709 • B-1600 Sint-Pieters-Leeuw • 02-363 00 40 • Fax: [phone]

CHINA: Yuan Chen Xin Building, Room 705 • 12 Yumin Road, Dewai, Madian • Beijing 100029 • 8610-6202-2886 • Fax: [phone]
FINLAND: Tietäjäntie 2 • 02130 Espoo • Phone: [phone] • Fax: [phone]
FRANCE: 3, allée des Garays • 91127 Palaiseau Cédex • 01-64 53 20 20 • Fax: [phone]
GERMANY: Landsberger Strasse 65 • 82110 Germering • 089/84 93 07-40 • Fax: [phone]
GREAT BRITAIN: Unit 2 Commerce Park, Brunel Road • Theale • Berkshire RG7 4AB • 0118 929 7500 • Fax: [phone]
INDIA: Flat 2B, Willocrissa • 14, Rest House Crescent • Bangalore 560 001 • 91-80-509-1320/21 • Fax: [phone]
ITALY: Viale San Gimignano, 38 • 20146 Milano • 02-48 39 16 01 • Fax: [phone]
KOREA: FL., URI Building • 2-14 Yangjae-Dong • Seocho-Gu, Seoul 137-130 • 82-2-574-7778 • Fax: [phone]
NETHERLANDS: Postbus 559 • 4200 AN Gorinchem • 0183-635333 • Fax: [phone]
SWEDEN: c/o Regus Business Centre • Frosundaviks Allé 15, 4tr • 169 70 Solna • 08-509 04 679 • Fax: [phone]
SWITZERLAND: Kriesbachstrasse 4 • 8600 Dübendorf • 01-821 94 44 • Fax: [phone]
TAIWAN: 1FL., 85 Po Ai Street • Hsinchu, Taiwan, R.O.C. • 886-3-572-9077• Fax: [phone]

28775 Aurora Road • Cleveland, Ohio 44139 • 440-248-0400 • Fax: [phone]

1-888-KEITHLEY (534-8453) • www.keithley.com

© Copyright 2001 Keithley Instruments, Inc.

Printed in the U.S.A.

11/01

Model 7172

Low Current 8

Instruction Manual

×

12 Matrix Card

©1991, Keithley Instruments, Inc.

All rights reserved.

Cleveland, Ohio, U.S.A.

Document Number: 7172-901-01 Rev. C

SAFETY PRECAUTIONS

The following safety precautions should be observed before using the Model 7172 and the associated instruments.

This matrix card is intended for use by qualified personnel who recognize shock hazards and are familiar with the safety
precautions required to avoid possible injury. Read over this manual carefully before using the mati card.

Exercise extreme caution when a shock hazard is present at the test circuit. User-supplied lethal voltages may be present

on the card connector jacks. The American National Standards Institute (ANSI) states that a shock hazard exists when

voltage levels greater than 3OV RM!? or 42.4V peak are present. A good safety practice is to expect that hazardous voltage

is present in any unknown circuit before measuring.

Do not exceed 200V between any two pins or between any pin and chassis.

Inspect the connecting cables and test leads for possible wear, cracks, or breaks before each use.

For maximum safety, do not touch the test cables or any instruments while power is applied to the circuit under test.
Turn off the power and discharge any capacitors before connecting or disconnecting cables from the matrix card.

Do not touch any object which could provide a current path to the common side of the circuit under test or power line

(earth) ground. Always make measurements with dry hands while standing on a dry, insulated surface capable of with-

standing the voltage being measured.

Do not exceed the maximum allowable input of the matrix card, as defined in the specifications and operation section of
this manual.

Instrumentation and accessories should not be connected to humans

Safety Precautions

The following safety precautions should be observed before using
this product and any associated instrumentation. Although some in­struments and accessories would normally be used with non-haz­ardous voltages, there are situations where hazardous conditions
may be present.

This product is intended for use by qualified personnel who recog­nize shock hazards and are familiar with the safety precautions re­quired to avoid possible injury. Read and follow all installation,
operation, and maintenance information carefully before using the
product. Refer to the manual for complete product specifications.

If the product is used in a manner not specified, the protection pro­vided by the product may be impaired.

The types of product users are:

Responsible body is the individual or group responsible for the use

and maintenance of equipment, for ensuring that the equipment is
operated within its specifications and operating limits, and for en­suring that operators are adequately trained.

Operators use the product for its intended function. They must be

trained in electrical safety procedures and proper use of the instru­ment. They must be protected from electric shock and contact with
hazardous live circuits.

Maintenance personnel perform routine procedures on the product

to keep it operating properly, for example, setting the line voltage
or replacing consumable materials. Maintenance procedures are de­scribed in the manual. The procedures explicitly state if the operator
may perform them. Otherwise, they should be performed only by
service personnel.

Service personnel are trained to work on live circuits, and perform

safe installations and repairs of products. Only properly trained ser­vice personnel may perform installation and service procedures.

Keithley products are designed for use with electrical signals that
are rated Installation Category I and Installation Category II, as de­scribed in the International Electrotechnical Commission (IEC)
Standard IEC 60664. Most measurement, control, and data I/O sig­nals are Installation Category I and must not be directly connected
to mains voltage or to voltage sources with high transient over -volt­ages. Installation Category II connections require protection for
high transient over-voltages often associated with local AC mains
connections. Assume all measurement, control, and data I/O con­nections are for connection to Category I sources unless otherwise
marked or described in the Manual.

Exercise extreme caution when a shock hazard is present. Lethal
voltage may be present on cable connector jacks or test fixtures. The
American National Standards Institute (ANSI) states that a shock
hazard exists when voltage levels greater than 30V RMS, 42.4V
peak, or 60VDC are present.

that hazardous voltage is present in any unknown circuit before
measuring.

A good safety practice is to expect

Operators of this product must be protected from electric shock at
all times. The responsible body must ensure that operators are pre­vented access and/or insulated from every connection point. In
some cases, connections must be exposed to potential human con­tact. Product operators in these circumstances must be trained to
protect themselves from the risk of electric shock. If the circuit is
capable of operating at or above 1000 volts,

the circuit may be exposed.

Do not connect switching cards directly to unlimited power circuits.
They are intended to be used with impedance limited sources.
NEVER connect switching cards directly to AC mains. When con­necting sources to switching cards, install protective devices to lim­it fault current and voltage to the card.

Before operating an instrument, make sure the line cord is connect­ed to a properly grounded power receptacle. Inspect the connecting
cables, test leads, and jumpers for possible wear, cracks, or breaks
before each use.

When installing equipment where access to the main power cord is
restricted, such as rack mounting, a separate main input power dis­connect device must be provided, in close proximity to the equip­ment and within easy reach of the operator.

For maximum safety, do not touch the product, test cables, or any
other instruments while power is applied to the circuit under test.
ALWAYS remove power from the entire test system and discharge
any capacitors before: connecting or disconnecting cables or jump­ers, installing or removing switching cards, or making internal
changes, such as installing or removing jumpers.

Do not touch any object that could provide a current path to the com­mon side of the circuit under test or power line (earth) ground. Always
make measurements with dry hands while standing on a dry , insulated
surface capable of withstanding the voltage being measured.

The instrument and accessories must be used in accordance with its
specifications and operating instructions or the safety of the equip­ment may be impaired.

Do not exceed the maximum signal levels of the instruments and ac­cessories, as defined in the specifications and operating informa­tion, and as shown on the instrument or test fixture panels, or
switching card.

When fuses are used in a product, replace with same type and rating
for continued protection against fire hazard.

Chassis connections must only be used as shield connections for
measuring circuits, NOT as safety earth ground connections.

If you are using a test fixture, keep the lid closed while power is ap­plied to the device under test. Safe operation requires the use of a
lid interlock.

no conductive part of

If a screw is present, connect it to safety earth ground using the
wire recommended in the user documentation.

!

The symbol on an instrument indicates that the user should re­fer to the operating instructions located in the manual.

The symbol on an instrument shows that it can source or mea­sure 1000 volts or more, including the combined effect of normal
and common mode voltages. Use standard safety precautions to
avoid personal contact with these voltages.

The

WARNING heading in a manual explains dangers that might

result in personal injury or death. Alw ays read the associated infor ­mation very carefully before performing the indicated procedure.

The

CAUTION heading in a manual explains hazards that could

damage the instrument. Such damage may invalidate the warranty.
Instrumentation and accessories shall not be connected to humans.
Before performing any maintenance, disconnect the line cord and

all test cables.

To maintain protection from electric shock and fire, replacement
components in mains circuits, including the power transformer, test
leads, and input jacks, must be purchased from Keithley Instru­ments. Standard fuses, with applicable national safety approvals,
may be used if the rating and type are the same. Other components
that are not safety related may be purchased from other suppliers as
long as they are equivalent to the original component. (Note that se­lected parts should be purchased only through Keithley Instruments
to maintain accuracy and functionality of the product.) If you are
unsure about the applicability of a replacement component, call a
Keithley Instruments office for information.

To clean an instrument, use a damp cloth or mild, water based
cleaner. Clean the exterior of the instrument only. Do not apply
cleaner directly to the instrument or allow liquids to enter or spill
on the instrument. Products that consist of a circuit board with no
case or chassis (e.g., data acquisition board for installation into a
computer) should never require cleaning if handled according to in­structions. If the board becomes contaminated and operation is af­fected, the board should be returned to the factory for proper
cleaning/servicing.

11/01

7172 8×12 Low Current Matrix Card

MATRIX CONFIGURATION: Single 8 rows×12 columns. Expanding

the columns can be done internally by connecting the rows of mul­tiple 7172 cards together with coax jumpers.

OFFSET CURRENT SELF TEST: An onboard electrometer circuit

measures offset current when the rear panel switch is pushed.
Pass/fail LEDs indicate if offset is above or below 500fA. The on­board SMB connector outputs voltage proportional to current
(1mV/10fA).

CROSSPOINT CONFIGURATION: 2-pole Form A (Signal, Guard).
CONNECTOR TYPE: 3-lug triax (Signal, Guard, Chassis).
MAXIMUM SIGNAL LEVEL: Pin to pin or pin to chassis: 200V. 1A

carry/0.5A switched, 10VA.

CONTACT LIFE: Cold Switching: 10

8

closures. At Maximum Signal

Level: 10

5

closures.

PATH RESISTANCE (Per Conductor): <1.0Ω initial, <1.5Ω at end of

contact life.

CONTACT POTENTIAL: Differential (Signal to Guard): <30µV.

Single ended (Guard to Guard or Signal to Signal): <60µV.

OFFSET CURRENT: <500fA, 150fA typical.

ISOLATION:

Path (Signal to Signal): >10

13

Ω, 0.4pF typical.

Differential (Signal to Guard): >10

9

Ω, 170pF typical.

Common (Signal and Guard to Chassis): >10

9

Ω, 430pF typical.

CROSSTALK (1MHz,50Ω Load): <–70dB.
INSERTION LOSS (1MHz, 50ΩLoad): 0.22dB typical.
3dB BANDWIDTH (50ΩLoad, 50Ω Source): 30MHz typical.
RELAY DRIVE CURRENT (Per Crosspoint): 30mA.
RELAY SETTLING TIME: <2ms.
EMC: Conforms to European Union Directive 89/336/EEC.
SAFETY: Conforms to European Union Directive 73/23/EEC (meets

EN61010-1/IEC 1010).

ENVIRONMENT:

Offset Current and Path Isolation Specifications: 23°C,

<50% R.H.

Operating: 0° to 50°C, up to 35°C at 70% R.H.
Storage: –25° to +65°C.

ACCESSORY SUPPLIED: Instruction manual and eight SMB expan-

sion cables (C99-1A).

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Offset current

self test

Contains information on Model 7172 features, specifica­tions, and accessories.

Details installation of the Model 7172 Low Current 8 x 12
Matrix Card within the Model 707 Switching Matrix, cov­ers card connections, and also discusses measurement
considerations.

Gives four typical applications for the Model 7172, includ­ing combined quasistatic and high-frequency CV meas­urements, van der Pauw resistivity measurements, and
semiconductor parameter analysis.

SECTION 1

General Information

SECTION 3

Applications

Contains performance verification procedures, trouble­shooting information and principles of operation for the
matrix card.

Lists replacement parts, and also includes component lay­out and schematic drawings for the Model 7172.

SECTION 4

Service Information

SECTION 5

Replaceable Parts

Table of Contents

SECTION 1 —

1.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

1.2 FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

1.3 WARRANTY INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

1.4 MANUAL ADDENDA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

1.5 SAFETY SYMBOLS AND TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

1.6 SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

1.7 UNPACKING AND INSPECTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

1.7.1 Inspection for Damage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

1.7.2 Shipment Contents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

1.7.3 Instrument Manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

1.8 REPACKING FOR SHIPMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

1.9 OPTIONAL ACCESSORIES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

1.10 COAXIAL JUMPER ACCESS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

SECTION 2 —

2.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.2 HANDLING PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.3 ENVIRONMENTAL CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.4 CARD INSTALLATION AND REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.5 CONNECTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

2.5.1 Card Connectors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

2.5.2 Recommended Cables and Adapters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

2.5.3 Triaxial to Banana Plug Adapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

2.5.4 General Instrument Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

2.5.5 Keithley Instrument Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11

2.5.6 Typical Test Fixture Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-17

2.6 MATRIX CONFIGURATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-18

2.6.1 Switching Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-18

2.6.2 Row Isolators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-20

2.6.3 Internal Matrix Expansion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-20

2.6.4 External Matrix Expansion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-23

2.7 MEASUREMENT CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-24

2.7.1 Magnetic Fields. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-24

2.7.2 Electromagnetic Interference (EMI). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-25

2.7.3 Ground Loops. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-25

2.7.4 Keeping Connectors Clean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-25

2.7.5 Noise Currents Caused by Cable Flexing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-26

2.7.6 Shielding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-26

2.7.7 Guarding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-28

2.7.8 Matrix Expansion Effects on Card SpeciÞcations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-29

General Information

Operation

SECTION 3 —

3.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

3.2 CV MEASUREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

3.2.1 Stand Alone System ConÞguration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

3.2.2 Computerized System ConÞguration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

3.2.3 Optimizing CV Measurement Accuracy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

3.2.4 Basic CV Test Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

3.2.5 Typical CV Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

3.3 SEMICONDUCTOR TEST MATRIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7

3.3.1 System ConÞguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7

3.3.2 Testing Common-Source Characteristic of FETs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8

3.4 RESISTIVITY MEASUREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9

3.4.1 Test ConÞguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9

3.4.2 Test Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9

3.4.3 Resistivity Calculations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12

3.5 SEMICONDUCTOR IV CHARACTERIZATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12

3.5.1 Test ConÞguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12

3.5.2 Cable Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12

3.6 SEMICONDUCTOR PARAMETER ANALYSIS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12

3.6.1 System ConÞguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14

3.6.2 Cable Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15

3.6.3 SPA Measurement Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15

3.6.4 Typical Test Procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15

Applications

SECTION 4 —

4.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

4.2 HANDLING AND CLEANING PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

4.3 OFFSET CURRENT SELF-TEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

4.4 PERFORMANCE VERIFICATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4

4.4.1 Environmental Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4

4.4.2 Recommended Test Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4

4.4.3 Offset Current VeriÞcation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

4.4.4 Path Isolation VeriÞcation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

4.4.5 Path Resistance VeriÞcation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9

4.4.6 Electrometer VeriÞcation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11

4.5 SPECIAL HANDLING OF STATIC-SENSITIVE DEVICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13

4.6 TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13

4.6.1 Recommended Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13

4.6.2 Using the Extender Card. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13

4.6.3 Troubleshooting Procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13

4.7 PRINCIPLES OF OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15

4.7.1 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15

4.7.2 ID Data Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15

4.7.3 Relay Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16

4.7.4 Power-on Safeguard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16

4.7.5 Isolator Relays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16

4.7.6 Electrometer Circuitry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16

Service Information

SECTION 5 –

5.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

5.2 PARTS LISTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

5.3 ORDERING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

5.4 FACTORY SERVICE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

5.5 COMPONENT LAYOUT AND SCHEMATIC DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

Replaceable Parts

List of Illustrations

SECTION 2 -

Figure 2-l
Figure 2-2

Figure 2-3 TriaxConnectorConfigumtion.. .............................................

Figure 2-4 TriaxialCablePreparation ...................................................

Figure 2-5 General Instrument Connections
Figure Z-6 Model 617 Electrometer Connections

Figure 2-7 Mode1196DMMConnections ................................................

Figure 2-8
Figure 2-9
Figure Z-10 Model 220 Current Source Connections
Figure 2-l 1 Model 236/237/m Source Measure Unit Connections
Figure 2-12 Typical Test Fixture Connections
Figure 2-13
Figure 2-14
Figure 2-15
Figure 2-16
Figure 2-17
Figure 2-18
Figure 2-19
Figure 2-20 PowerLineGromdLoops
Figure 2-21
Figure 2-22
Figure 2-23
Figure 2-24
Figure 2-25

Operation

Model7172Installation .....................................................

CardConnectors ..........................................................

..............................................

........................................... 2-11

Model 230 Voltage Source Connections
Model 590 CV Analyzer Connections

Equivalent Circuit of Test Fixture Connections

Model7172MatrixOrganization ..............................................

Conn&ingTbreeCardsfor8x36Matrix

JumperCo~~orLoca~ons .................................................

ThreeCardsinDaisyChainConfiguration ......................................

l6x36MatrixConstructedbyExtemalJumpering

Using Triax Tee Adapters to Daisy Chain Cards

..................................................

FkninatingGroundLoops ..................................................

Shi&iingExample ........................................................

DualShieldTestFiiture ....................................................

GuardedCircuit
Typical Guarded Signal Connections

..........................................................

......................................... 2-13

.......................................... 2-14

.........................................

............................. 2-16

.............................................

................................... 2-18

....................................... 2-21

................................ 2-23

.................................. 2-24

...........................................

2-2
2-3
2-4
24
2-6

2-12

2-15

Z-17

2-19

2-21
2-22

2-25

2-25

2-27

2-27

2-28

2-29

SECTION 3

Figure 3-l Stand Alone CV System Configuration
Figure 3-2 computerized CV system configuration

Figure 3-3
Figure 3-4 Typical High-frequency CV Curve Generated by Model 590
Figure 3-5
Figure 3-6
Figure 3-7
Figure 3-8
Figure 3-9 Resistivity Measurement Conventions
Figure 3-10
Figure 3-11 Semiconductor Parameter Analysis Switching System
Figure 3-12

Figure 3-13
Figure 3-14

- Applications

...............................

.............................

Typical Quasistatic 07 Curve Generated by Model 595

Semiconductor Test M&ix
System Configuration for Me

Typical Common-Same FET IV Cbaractexistics

Resisti~~TestConfiguration ......................................

Multi Unit Test System Using Models 236 and 237 Source Measure Units.

Sl’ACo~eciions ...............................................

System Configuration for JPET Test

TypicalJFETPlot ...............................................

........................................ 3-7

aswing Common-Emitter Characteristics

...............................

..................................

...................

........................

....................

...............

.......

.....

3-2

3-3

3-5

3-6

3-8
3-9
3-10
3-11
3-13
3-14
3-16

3-17
3-18

SECTION 4 - Service

Information

Figure 4-l
Figure &2
Figure 4-3 Offset Verification Test Connections

Figure 44 Conmctions for Path Isolation Verification ...............

Figure 4-5
Figure 4-6
Figure 4-7
Figure 48
Figure 4-9
Figure 4-10
Figure 4-11
Figure 4-12

switch for offset Current Self-test

DMMConnectiontoSMBofMode17172 .................

Triaxial Cable Preparation

Connections for path Resistance Verification ..............

Shorting Measurement Paths Using Trim Tee Adapter ......

Verificatin of On-board Electrometer
IDDataTiming
Model 7172 Block Diagram

Simplified Schematic of On-Board Electrometer. ...........

Siiplified Model of Current to Voltage Converter ..........

.....................................

............................

......................

....................

....................

...........................

4-l
4-3
46
4-7
4-8
4-9
4-10
4-12
4-14
4-15
4-17
4-18

List of Tables

SECTION

Table 2-l Recommended Cables and Adapters
Table 2-2 PartsforSpecialTriaxialCable
Table 2-3 Column Numbering by Slot and Unit

SECTION

Table 3-l CV Test Crosspoint Summary . . . .

Table 52

Table 3-3 Crosspoint Summary for JFET Test . . . . .

SECTION

Table 4-l
Table 42
Table 43

2 - Operation

...........

...............

..........

3 - Applications

Crosspoint summary

for Resistivity Measurements

4 - Service Information

Recommended Verification Equipment . .
Recommended Troubleshooting Equipment

Troubleshooting Procedure . . . . .

...........

...........

...........

...........

...........

...........

...........

...........

...........

24
24
Z-20

34
3-10
3-15

44
4-13
4-14

SECTION 1

General Information

1 .l INTRODUCTION

This section contains general information about the

Model 7172 Low Current 8 x 12 Ma&ix Card. The Model
7172 is designed to complement the Model 236 Source
Measure Unit in semiconductor testing and other low
current switching applications. (The Models 737 and 238
Source Measure Units can also be used, within the speci­fied maximum signal levels of the Model 7172.)

Section 1 is armnged in the following manner:

1.2 Features
13 warranty Informaticm

1.4 Manual Addenda

1.5 Safety Symbols and Terms

1.6 Specifications

1.7 Unpacking and Inspection

1.8 Repacking for Shipment

1.9 Optional Accessories

effects of stray capacitance, leakage current, and leak­age resistance.

.

Model 7l72 cards can be internally connected together
or to Model 7072 cards using supplied SMB to SMB

2.p.w to expand the number of columns in the ma-

1.3 WARRANTY INFORMATION

Warranty information is located on the inside front cover
of this instruction manual. Should your Model 7172 re­quire warranty service, contact the Keithley representa­tive or authorized repair facility in your area for further
information. when returning the matrix card for repair,
be sure to fill out and include the service form at the back
of this manual in order to provide the repair facility with

the necessary information.

1.4 MANUAL ADDENDA

Any improvements or changes concerning the matrix

card or manual will be explained in an addendum in­cluded with the the unit. Be sure to note these changes
and incorporate them into the manual before using or
servicing the unit.

1.10 Coaxial Jumper Access

1.2 FEATURES

Keyfeatoresof theModel7172LowCurrent8x12Matrix
Card in&de:

. 8 x 12 (eight row by 12 column) switching matrix.

l AII paths have <5OOfA of offset current and typical val-

ues of 150fA.

. Electrometer to measure the offset current on the card

as a self-test. Front panelLED givepass/fail informa-

tion or PCB connector gives voltage proportional to

off& (lmV=lOfA).

. Threelug triax connectors for all row and columns al-

low guarding of each signal pathway to minimize the

1.5 SAFETY SYMBOLS AND TERMS

The following symbols and terms may be found on an in­strument or used in this marmat.

Then

user should refer to the operating instnxtions located in
the instrLlction manual.

ti

The
may be present on the terminal(s). Use standard safety
precautions to avoid personal contact with these volt­ages.

symbol on an in&rument indicates that the

symbol on an instrument shows that high voltage

1-l

SECTION I
General Information

The WARNING heading used in this manual explains
dangers that might result in personal injury or death. Al­ways read the associated information very carefully be
fore performing the indicated procedure.

The CAUTION heading used in this manual explains
hazards that could damage the matrix card. Such damage
may invalidate the warranty.

1.6 SPECIFICATIONS

Model 7172 specifications may be found at the front of
thismanual. These specifications are exclusive of the ma­trix mainframe specifications, which are located in the

Model 707 Instruction Manual.

1.7 UNPACKING AND INSPECTION

1.7.1

Upon receiving the Model 7172, carefully unpack it from
its shipping carton and inspect the card for any obvious
signs of physical damage. Report any such damage to the
shipping agent immediately. Save the original packing
carton for possible future reshipment.

Inspection for Damage

manual package includes an instruction manual and any
pertinent addenda.

1.8 REPACKING FOR SHIPMENT

Should it become necessary to return the Model 7172 for
repair, carefully pack the card in its original packing car­ton or the equivalent, and include the following informa­ti0l-l:

. Advise as to the warranty status of the matrix card.
. Write ATTENTION REPAIR DEl’ARTMEiVT on the

shipping label.

. Fill out and include the service form located at the back

of this manual.

1.9 OPTIONAL ACCESSORIES

Model 237.ALG-2 -A 2m (2.4 ft.) low noise hiax cable
terminated with a 3-&t male triax connector and alliga­tor clips.

Model 237-BAN-3 -A 3 ft. low noise tiax cable tern%
nated with a 3slot male triax connector and a banana

plug.

1.7.2

The following items are included with every Model 7172

order:
. Model 7172 Low Current 8 x 12 Matrix Card.

l Model 7172 Instruction Manual.
l Coaxial jumper cables (8) for matrix expansion.

. Additional accessories as ordered.

Shipment Contents

1.7.3 Instruction Manual

The Model 7172 Ji~~trwtion Manual is three-hole drilled
so that it can be added to the three-ring binder of the
Model 707 Switching
removing the plastic wrapping, place the manual in the
binder after the mainframe insfxuction manual. Note that
a manual identification tab is included and should pre­cede the matrix card instruction manual.

If an additional instruction manual is required, order the
manual package, Keithley part number 7172-901-00. The

Matrix Instiction

Manual. After

Models 237.TRX-T and 7078-m-T - These are 3slot
male to dual 3-lug female triax tee adapters. The Model
237-TRX-T is for high voltage applications.

Model 707%TRX-3 -A 3 ft low noise triax cable termi­nated with 3slot male triax connectors. Also available in
10 and 20 ft. lengths as Models 7078-TRX-10 and

7078-TRX-20.

Models 7078-TRX-BNC and 707%TRXGND - These are
3-slot male triax to female BNC adapters. The Model
7078-TRX-GND is for non-guarded applications.

Model 707%TBC 3-Lug Female Triw Bulkhead Connec­tor with Cap-The Model 7078-TBC can be used for ap­plications such as test fixtures.

Model 7078-CSHl’ Cable Set-The Model 7078-CSHp
Cable Set includes the necessary cables and adapters to
connect the Model 7172 to the Hewlett-Packard Model
4145 Semiconductor Parameter Analyzer. The Model

l-2

General

SECTION 1

Information

7078CSHP includes four Model 707%TRX-10 loft. 3-lug
triaxial cables, four Model 7051-10 loft. BNC cables, and
four Model 707%TRX-BNC 34ug triax to BNC adapters.

Recommended cables and adapters are summarized in
Table 2-l.

1 .lO COAXIAL JUMPER ACCESS

Coaxial jumpers can be installed to expand rows A-H of

the matrix using two or more Model 7172 Cards. An ac­cess door on the mainframe allows access to these jump-

ers. To allow access when the Model 707 is mounted in a
rack, it is recommended that the Model 7079 Slide Rack
Mount Kit be used.

l-3

SECTION 2

Operation

2.1 INTRODUCTION

This section contains information on mati card connec­tions, installation and matrix programming,
ranged as follows:

2.2 Handling Precautions: Discusses precautions that
should be taken when handling the card to avoid con­tamination that could degrade performance.

2.3 Environmental Considerations: Outlines environ­mental aspects of using the Model 7172.

2.4 Card Installation and Removal: Details installation
in and removal from the Model 707 Switching Matrix

and is ar-

mainframe.

2.5 Connections: Discusses card connectors, cables and
adapters, and typical connections to other instrumenta­tion.

26 Matrix Configuration: Discusses the switchingma­ti, as well as matrix expansion by connecting two or
more cards together.

2.7 Measurement Considerations: Reviews a number
of considerations when making low-level current and ca­pacitance measurements.

the mainframe and matrix card only in a clean environ­ment. If contamination is suspected, clean the card as dis­cussed in Section 4. Also, the performance verification
procedures in Section 4 can be used to test the card for
low leakage resistances that could signal contamination.

2.3 ENVIRONMENTAL CONSIDERATIONS

For rated performance, the card should be operated
within the temperature and humidity limits given in the
specifkations at the front of this manual. Note that cur­rent offset and path isolation values are spekfied within a
lower range of limits than the general operating environ­ment.

2.4 CARD INSTALLATION AND REMOVAL

Before making connections, the Model 7172 should be ir­stalled within the Model 707 Switching Matrix, as sum­marized below. Figure 2-l shows the installation proce­dure.

WARNING
Turn off the
nect the line cord before installing orremov­ing matrix cards.

mainframe

power and discon-

2.2 HANDLING PRECAUTIONS

To maintain high impedance isolation, care should be
taken when handling the mati card to avoid contami­nation from such foreign materials as body oils. Such
contamination can substantially lower leakage resis­tances, degrading performance. The areas of the card that
are most sensitive to contamination are those associated
with the Teflon@ insulators. To avoid any possible con­tamination, always grasp the card by the handle or the
card edges. Do not touch board surfaces, components, or
card edge connectors.

Dirt build-up over a period of time is another possible
source of contamination. To avoid this problem, operate

NOTE
The coaxial jumpers used to expand the ma­hiw with two or more Model 7172 cards are
not installed before card insertion; an access
door on top of the mainframe allows access to
the connectors after the card is installed.

1. Before installing the card, make sure the access door
on top of the Model 707 is fully closed and secured.
The access door contains tracks for the card slots and
must be in place to properly install the card.

2. With one hand grasping the handle, and the other
holding the bottom of the card, line up the card with
the tracks in the desired slot. Make certain that the
component side of the card is facing the fan on the
mainframe.

2-l

SECTION 2
Operation

Fimre 2-l. Model 7172 Installation

CAUTION
Do not touch the card surfaces or any compo- properly secure this ground connection may
nents to avoid contamination that could de- result in personal injury or death due to elec­grade card performance. tric shock.

3. Slide the card into the mainframe until it is properly
seated in the edge connectors at the back of the slot.
Once the card is properly seated, secure it to the

mainframe

?.cTews.

The mounting screws must be secured to en­sure a proper chassis ground connection be-

2-2

by finger tightening the spring-loaded

WARNING

tween the card and the mainframe. Failure to

4. To remove a card, first turn off the power and dis­connect the line cord from the mainframe. Discon­nect all external and internal cables (internal cables
can be reached through the access door). Loosen the
mounting screws, then pull the card out of the main­frame by the handle. When the back edge of the card
clears the

tom

mainframe,

edge near the back edge.

support it by grasping the bot-

2.5 CONNECTIONS

SECTION 2

Operation

Card connectors, recommended cables and adapters, and

typical connections to test instruments are discussed in
the following paragraphs.

2.5.1

The card connectors are shown in Figure 2-Z. Each row

and column is equipped with a 3-lug female hiax connec­tor. As shown in Figure 2-3, the center conductor is SIG-

NAL, the inner shield is GUARD, and the outer shield, or

shell is chassis ground. Note that slug connectors are

wed to avoid possible damage from inadvertently at-

tempting to connect BNC cables.

The Model 7172 has 12 cohmms that are labeled 1

through 12, as well as eight rows, A through H.

Card Connectors

CAUTION

Do not

between any pin and chassis.

exceed 2OOV between any two pins or

Mounting

screw

I

2.5.2 Recommended Cables and
Adapters

Table 2-1 summarizes the cables and adapters recom­mended~ for use with the Model 7172. Equivalent user­supplied items may be substituted as long as they are of
sufficient quality (low offset current, high leakage resis­tance). Using substandard cables and adapters may de­grade the integrity of the measurements made using the
matrix card. See paragraph 2.7 for a discussion of meas­urement considerations.

2.5.3

For instruments that use banana
cable terminated with a 3-&t male triax and a single ba­nana plug. Use the Model 237-BAN-3 or prepare a special
cable as outlined below using the parts listed in Table 2-2.

With the Model 237-BAN-3, the center conductor of the

triax is connected to the banana plug. The inner and outer
shields have no connection. With the special cable shown
in Figure 2-4, the inner shield is shorted to the center con­ductor. Which cable to use depends on your application.

Triaxial to Banana Plug Adapter

jacks, you need a triax

Mounting

screw

+ure 2-2.

Note that you can use either an unterminated triax cable,
or cut a dual-connector cable (7078-TRX-10) in half to
construct two special cables.

Card Connectors

2-3

SECTION 2
Operation

Chassis
Ground

2oov -

Peak

Caution : Do not Exceed Maximum

Voltage

Levels Shown

Table 2-2. Parts for Special Triaxial Cable

Keithley Part or
Model Number Description

7078.TRX-3 triax Triax cable terminated with
cable*
Part # BG-10-2

3-slot male triax connectors
Red banana plug

F” P,

I I

r

I_ 1”---4

I

Figure 2-3.

Table 2-1. Recommended Cables and Adapters

Model
7078-TRX-x
237-BAN-3
237-ALG2

7078-TRX-BNC

7078-TRX-GND

707%TRX-T
6171
CA-93-l

Pomona 1269

Trim Connector Configuration

Description
3-slot male triax connectors on

both ends (x = 3,lO or 20 ft.)
3-slot male triax to male banana

Plug
3-&t male triax to alligator clips

3-slot male triax to BNC adapter,
connections to center and inner
shell
3slot male triax to BNC adapter,
connections to center and outer
shell
3slot male to dual 3-lug female
triax tee adapter
3slot male tiax to Z-lug female
triax adapter
BNC to right angle SMB cable
Female BNC to female banana
adapter.

(A) Cut off insulation with knife.

Cut off outer shield.

Insulation Over
Inner Shield

I

(6) Strip insulation off inner shield

(C) Twist inner shield then strip inner conductor.

Twist inner shield and center conductor together,

slip on plastic cover.

(D) Insert wires into hole and wrap around

body.

2-4

(E) Screw on plastic cover.

Fifflre 24. Trimial Cable Preparation

SECTION2

Operation

1. Using a knife, cut and strip back the outer insulation
about l-1/2 inches.

2. Remove the outer insulation, then cut away the outer
shield back as far as the insulation is shipped.

3. carefully strip away the insulation over the inner
shield one inch, then cut the inner shield off even
with the stripped insulation.

4. Strip the inner conductor l/2 inch, then twist the
strands together.

5. Unscrew the cover from a banana plug, then slide
the cover over the center conductor of the triax cable.

6. Insert the stripped center conductor through the
hole in the body of the banana plug, then wrap the
wire around the plug body.

7. Screw on the plastic cover, and make certain the wire
is secure by gently pulling on the plug.

2.5.4 General Instrument Connections

The following paragraphs discuss connecting the Model
7172 to various general classes of iwhumentation such as
DMMs, electrometers, sources, and source/measure
units. Because these configurations are generic in nature,
some modification of the connecting schemes may be
necessary for your particular inshumentation. Also, spe
cial cables or adapters may be necessary. Jn all cases,
3-lug triax cables must be used to make the connections.

WARNING

Hazardous voltage from other guard sources

may be present on LO or the DUT if other

crosspoints are closed.

4-w& DMM co~ections are shown in Figure 2-5 (C). In
this case, a total of four jacks are required; HI, LO, SENSE
HI, and SENSE LO.

Electrometer Connections
Typical electrometer connections are shown in Figure 2-5

(D) through (G). The unguarded volts connections in (D)
show the HI signal path routed through one jack, and the
LO path goes through the other connector. Both GUARD
pathways are connected to electrometer LO. For guarded
voltage (E), Model 7172 GUARD is connected to elec­trometer GUARD.

The connections for elecmmeter fast amps and resis-

tame measurements are shown in Figure 2-5 (F) and (G).
These configurations are essentialIy the same as those

discussed above. For the case of fast amps, both GUARD

paths are connected to electrometer LO, while in the case

of guarded resistance, one GUARD path is connected to

electrometer GUARD, and the other GUARD path is con-

nected to electmmeter LO.

WARNING
Do not use coaxial cables ,md adapters be­cause hazardous voltage from guard sources
may be present on the cable shields.

Figure 2-5 shows the general instrument comwztions for

the discussions below. Note that DUT guarding or
shielding are not indicated here; see Figures 2-21 and 2-24
for shielding and guarding information. As shown, alI
figures assume instruments are connected to rows, and
the DUT is connected to columns.

DMM Connections

General DMM connections are shown in Figure 2-5 (A),
(B), and (0. Floating connections are shown in (A), with
LO and HI routed to two separate jacks on the Model

7172. The common LO conmxtions in (B) should be used
only for non-critical applications because the perform­ance of the GUARD pathway is not specified.

Source Connections
Voltage and current source connections are shown in

Figure 2-5 (H) through (J). The HI and LO paths of the
voltage source (H) are routed through two jacks, with
both card GUARD pathways connected to voltage source
LO. For the unguarded current sauce co~ectiom (I),
card GUARD is again connected to source LO, with
source HI and LO routed through two pathways. In the
case of the guarded current source in (J), card GUARD of
the HI signal path is connected to source GUARD, and
the other GUARD path is connected to source LO.

Source/Measure Unit Connections

Figure 2-5 (T) shows typical connections for a source/

measure unit (Siviu). In this instance, a remote-sensing
type of a SMU is shown, requiring a total of four signal
pathways to the DUT. For critical measurements, both
source and sense HI pathways would be guarded as
shown, with two of the four card GUARD pathways con­nected to SMU GUARD terminals. As with other instru­ment connections, the LO card GUARD pathways are
connected to SMU LO terminals.

2-5

SECTION 2
Operation

Rows

A.) DMM Floating

Warning : Hazardous voltage from guard

so”rces may be pres*“t on LO.

r----

L----J

7172

7172

-j

Columns

U

Note : Use this configuration only for

non-critical measurements.

Figure Z-5.

B.) DMM Common LO

GeneralInstrument Connections (A-B)

2-6

SECTION 2

Operation

C.) DMM 4Wre

Flows

r - - - - 7 Columns

DUT

L-----l

7172

Figure 2-5.

ROWS

D.) Electrometer. Unguarded Volts

General Instrument Connections (C-D)

r----i

(cont.)

Columns

DUT

2-7

SECTION 2
Operation

E.) Electrometer, Guarded ‘Job

-3 r-

F.) Electmmetsr. Fast Current

7172

L----A

7172

Figure 2-5.

2-8

-7-J J-i-+-

G.) Electrometer. Resistance (Guarded)

General Instrument Connections (E-G)

L----A

7172

(cont.)

H.) Voltage Source

SECTION 2

Operation

-7-J $-+-

L----A

7172

-7-2 Jr+-

I.) current source, unguarded

J.) Current Source, Guarded

Figure 2-S. General Instrument Connections (H-I) (cont.)

L----A

7172

7172

2-9

SECTION 2

Operation

DUT

KJ SourcelMeasure Unit

Notes : DtJT shielding/guarding not shown. See Figures 2-21 and 2-24.

Figure 2-5. General Instrument Connections (K) (cont.)

L-----l

7172

Z-10

SECTION 2

Operation

2.5.5

Keithley Instrument Connections

The following paragraphs outline connecting typical
Keithley instruments to the Model 7172 Low Current 8 x

12 Matrix Card. Other similar instruments can be con­nected using the same cabling as long as their input/out­put configurations are the same. Instrument connections
covered include:

l Model 617 Electrometer/Source
l Model 196 DMM
l Model 230 l’rogmmmable Voltage Source
l Model 220 Programma
l Model 590 CV Analyzer
l Model 236/237/238 Source Measure Unit

ble Current Source

Model 617 Electrometer Connections
ComwctionsfortheMode1617Electrometerareshownin

Figure 2-6. Tlw electrometer INPUT and COM can be

connected to any row. Figure 24 shows connections to
rows A and B.

1. Connect one end of a Model 7078-TRX-3 or -10 3-lug
triaxial cable to row A of the Model 7172.

2. Connect the other end of the triax cable to the Model
617 INPUT connector using a Model 6172 adapter.

3. Connect

the trim end of a t&w/banana cable to row

B of the Model 7172.

4.

Connect the banana plug end of the t&x/banana ca­ble to the COM terminal of the Model 617. The short­ing link between COM and chassis qound should be
removed for this application.

5.

Place the GUARD switch in the OFF position.

6. To connect the voltage source to the Model 7172,
connect the V-SOURCE HI and LO connectors of the
Model 617 to the desired row connectors on the ma­trix card. Fiwre 2-6 shows connections to rows C
andD. -

Figure 2-6.

6172 2-Slot to 3-h \
Triax Adapter -

Note : See Figure 2-4 for special triax

ii-“’

to banana cable.

Model 617 Electrometer Connections

\ II

237~BAN-3 1

7172

Matrix Card

2-11

SECTION2
Operation

Model 196 DMM Connections

Connect the Model 196 or other similar DMM to the ma­trix card using the general configuration shown in
FigureZ-7. The VOLTS OHMS HI and LO terminals
should be connected to the desired rows using triax/ba­nana cables. For 4-w& ohms measurements, the OHMS
SENSE Hl and LO terminals should be connected to two
additional rows using the same type of cables.

NOTE
For low-level voltage measurements, connect
the inner shield of the HI cable to VOLT
OHMS LO to

minimize noise.

Model 230 Voltage Source Connections
Connect the Model 230 OUTPUT and COMMON termi-

nals to the desired rows using t&x/banana plug cables,

as shown in Figure 2-E. For remote sensing applications,
the SENSE OUTPUT and SENSE COMMON connectors
can be routed through two additional rows using similar
cables.

Model 590 CV Analyzer Connections

The Model 590 CV Analyzer can be connected to any KXV

or any column as shown in Figure 2-9. The BNC cables
that are supplied with the Model 590 can be used; how­ever, Model 707%TRX-BNC triax-to-BNC adapters must

be used at the Model 7172 end.

Figure

196 DMM

Connect inner shield to LO for
low-level measurements.

(Modify the

2-7.

cable

of Figure 2-4.)

Model 196 DMM Connections

-A

L

Note : See Figure 2-4

for special triax
to banana cable.

LO

7 ‘172 Matrix Card

-

2-12