Stanford Research Systems SIM910 Operating Manual

Operation and Service Manual

Stanford Research Systems

JFET Preamp

SIM910

Revision 2.1 • May 8, 2007

Certification

Stanford Research Systems certifies that this product met its published specifications at the time
of shipment.

Warranty

This Stanford Research Systems product is warranted against defects in materials and workman­ship for a period of one (1) year from the date of shipment.

Service

For warranty service or repair, this product must be returned to a Stanford Research Systems
authorized service facility. Contact Stanford Research Systems or an authorized representative
before returning this product for repair.

Information in this document is subject to change without notice.

Copyrightc Stanford Research Systems, Inc., 2003 – 2007. All rights reserved.

Stanford Research Systems, Inc.
1290–D Reamwood Avenue
Sunnyvale, CA 94089 USA
Phone: [phone] • Fax: [phone]

www.thinkSRS.com • e-mail: [e-mail]

Printed in U.S.A. Document number 9-01553-903

SIM910 JFET Preamp

Contents

General Information iii

Safety and Preparation for Use . . . . . . . . . . . . . . . . iii

Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv

Notation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . vi

1 Operation 1 – 1

1.1 Instrument Overview . . . . . . . . . . . . . . . . . . . 1– 2

1.2 Front Panel Operation . . . . . . . . . . . . . . . . . . 1 – 2

1.3 Rear Panel Output . . . . . . . . . . . . . . . . . . . . 1 –5

1.4 SIM Interface . . . . . . . . . . . . . . . . . . . . . . . . 1 – 6

2 Remote Operation 2 – 1

2.1 Index of Common Commands . . . . . . . . . . . . . . 2 – 2

2.2 Alphabetic List of Commands . . . . . . . . . . . . . . 2– 3

2.3 Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2– 4

2.4 Commands . . . . . . . . . . . . . . . . . . . . . . . . . 2 – 5

2.5 Register Model . . . . . . . . . . . . . . . . . . . . . . 2 – 9

3 Performance Tests 3 – 1

3.1 Offset . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 – 2

3.2 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . 3 – 2

3.3 Performance Tests . . . . . . . . . . . . . . . . . . . . . 3 – 3

3.4 SIM910 Performance Test Record . . . . . . . . . . . . 3 – 4

4 Circuitry 4 – 1

4.1 Circuit Discussion . . . . . . . . . . . . . . . . . . . . . 4 – 2

4.2 Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . 4– 4

4.3 Schematic Diagrams . . . . . . . . . . . . . . . . . . . 4 – 4

i

ii Contents

SIM910 JFET Preamp

General Information

The SIM910 JFET Preamp, part of Stanford Research Systems’ Small
Instrumentation Modules family, is a low noise general purpose volt­age preamplifier with bandwidth from DC to 1 MHz.

Safety and Preparation for Use

Biomedical Applications

Under certain conditions, the SIM910 may prove to be unsafe for

WARNING

Regarding Use with Photomultipliers

CAUTION

applications involving human subjects. Incorrect grounding, com­ponent failure, and excessive common-mode input voltages are ex­amples of conditions in which the instrument may expose the subject
to large input currents. Therefore, Stanford Research Systems does
not recommend the SIM910 for such applications.

The front-end amplifier of this instrument is easily damaged if a
photomultiplier is used improperly with the amplifier. When left
completely unterminated, a cable connected to a PMT can charge
to several hundred volts in a relatively short time. If this cable is
connected to the inputs of the SIM910, the stored charge may damage
the front-end JFETs. To avoid this problem, provide a leakage path of
about 100 kΩ to ground inside the base of the PMT to prevent charge
accumulation.

Service

Do not install substitute parts or perform any unauthorized modifi­cations to this instrument.

The SIM910 is a single-wide module designed to be used inside the
SIM900 Mainframe. Do not turn on the power until the module is
completely inserted into the mainframe and locked in place.

iii

iv General Information

Symbol Description

Alternating current

Caution - risk of electric shock

Frame or chassis terminal

Caution - refer to accompanying documents

Earth (ground) terminal

Battery

Fuse

On (supply)

Off (supply)

Symbols you may Find on SRS Products

SIM910 JFET Preamp

General Information v

Notation

The following notation will be used throughout this manual:

WARNING

CAUTION

A warning means that injury or death is possible if the instructions
are not obeyed.

A caution means that damage to the instrument or other equipment
is possible.

• Front-panel buttons are set as [Button];
[Adjust ] is shorthand for “[Adjust ] & [Adjust ]”.

• Front-panel indicators are set as OVLD.

• Remote command names are set as *IDN?.

• Literal text other than command names is set as OFF.

SIM910 JFET Preamp

vi General Information

Specifications

Performance Characteristics

Frequency range DC to 1 MHz; −3 dB @ 1.9 MHz, typ.

Gain 1, 2, 5, 10, 20, 50, 100

Gain accuracy ±0.5 % DC to 100 kHz

± 5 % @ 1 MHz, typ.

Gain stability 200 ppm/◦C

Input voltage noise (RTI, gain ≥ 10) 4 nV/√Hz@ 1 kHz, typ.

gain 1 12nV/√Hz@ 1 kHz, typ.

Input current noise <10 fA/√Hz, typ.

Input impedance 100MΩ // 35 pF

Input Bias Current (DC) 0.5 pA, typ.

Output impedance 50Ω

AC coupling frequency 16 mHz −3dB

Input selection A, A−B, GND
Input coupling AC or DC

Input shields Floating or ground

Maximum input, differential ±1 V before overload

Maximum input, common-mode ±5 V

clamped at ±6 V
Maximum output voltage ±10 V before overload
Maximum output current ±100 mA before overload

Maximum slew rate 0.4 V/µs RTI, typ.

2.4 V/µs RTO, typ.

CMRR 85 dB @ 1 kHz

Offset stability ±10 ppm/◦C max

General Characteristics

Operating temperature 0◦C to 40◦C, non-condensing

Power +5 V (50 mA typ., 100 mA max.)

±15 V (50 mA typ., 300 mA max.)

Interface Serial (RS-232) through SIM interface

Connectors BNC (3 front, 1 rear)

DB–15 (male) SIM interface

Weight 1.5 lbs

Dimensions 1.500W × 3.600H × 7.000D

SIM910 JFET Preamp

1 Operation

In This Chapter

The SIM910 JFET Preamp is a flexible low noise voltage preamplifier
for general use from DC to 1 MHz. This chapter gives the necessary
information to get started quickly with the SIM910.

1.1 Instrument Overview . . . . . . . . . . . . . . . . . . 1 – 2

1.2 Front Panel Operation . . . . . . . . . . . . . . . . . . 1– 2

1.2.1 Gain . . . . . . . . . . . . . . . . . . . . . . . . 1 – 3

1.2.2 Offset . . . . . . . . . . . . . . . . . . . . . . . . 1 – 3

1.2.3 Overload . . . . . . . . . . . . . . . . . . . . . . 1– 3

1.2.4 Inputs . . . . . . . . . . . . . . . . . . . . . . . 1 – 4

1.2.5 Output . . . . . . . . . . . . . . . . . . . . . . . 1 – 4

1.3 Rear Panel Output . . . . . . . . . . . . . . . . . . . . 1 – 5

1.4 SIM Interface . . . . . . . . . . . . . . . . . . . . . . . 1 – 6

1.4.1 SIM interface connector . . . . . . . . . . . . . 1 – 6

1.4.2 Direct interfacing . . . . . . . . . . . . . . . . . 1 – 6

1 – 1

1 – 2 Operation

A

B

INPUT
A / A-B

AC /
DC

SHIELD
FLOAT/GND

INPUT
GROUND

+

-

FRONT
END

PROGRAMMABLE
GAIN

Ω

50

OUTPUT

REAR
PANEL
OUT

INPUT
PROTECTION

1.1 Instrument Overview

The SIM910 is a voltage preamplifier with low input and output
noise. It provides selectable gain from 1 to 100 of a single ended or
true differential signal. The amplifier runs from DC to 1 MHz, or can
be AC coupled with 16 mHz −3dB frequency. In addition, the input
BNC shields can be grounded or floated allowing the signal ground
to be referenced to a local or remote ground. An overload light
indicates when the input or output maximum voltage, or maximum
output current has been reached.

The amplifier settings can be controlled either by the front panel
buttons or the remote serial interface. Digital noise is eliminated by
only clocking the microprocessor when settings are being changed.
The complete amplifier configuration (i.e., gain settings, coupling,
etc.) is saved in non-volatile memory.

The front end amplifier of this instrument is protected with a pair of
100 Ω resistors (R103 & R104). Note that the internal-grounding in­put configuration grounds the amplifier inputs after these protection
resistors.

1.2 Front Panel Operation

A block diagram of the amplifier is shown below in Figure 1.1.

Figure 1.1: The SIM910 block diagram.

All SIM910 configurations can be specified either from the front
panel, or by commanding through the remote serial interface. The
front panel is shown below (Figure 1.2). The front panel contains the

SIM910 JFET Preamp

1.2 Front Panel Operation 1 – 3

gain settings, the overload light, the input settings, the coupling and
the shield states, and the buttons to control them.

1.2.1 Gain

1.2.2 Offset

1.2.3 Overload

Figure 1.2: The SIM910 front and rear panel.

The gain is selectable from 1 to 100. Gain settings are 1, 2, 5, 10, 20, 50,
and 100 and are displayed as a product of 1, 2, or 5 and a multiplier
of 10 or 100. Gain is raised or lowered by pressing [Gain ] or [Gain ]
in the GAIN block on the upper right of the module. The change
is reflected in the LEDs to the left of the buttons. Pushing [Gain ]
when on gain 100 produces no effect. Pushing [Gain ] when on gain
1 produces no effect.

The offset is adjustable through a hole in the GAIN block of the
front panel with a small flat head screwdriver. See Section 3.1 for a
description of the offset trimming procedure.

There is an overload light in the gain section of the front panel. OVLD
is lit when the input common mode is outside ±5 V, the input signal is

SIM910 JFET Preamp