Preamble Instruments 1850A, 1855A Operator's Instruction Manual

0

0
0
e

0
0

0
0
0
0

0
0

0
0
0
0

0

0
0
0
0

0
0
0

0
0
0

e
0

0
0

0
0
0
0

e
0

0
e
0

e

0
e
e

pREAMBLE

- VIINSTRUMENTS

1850A and 1855A

DIFFERENTIAL AMPLIFIERS

March 10, 1999

PREAMBLE INSTRUMENTS, Inc,
P.O. Box 6118
Beaverton, OR 97007-0118

0
0
0

0
0
0
0

0
0
0
0

0
0

0
0
0
0

0
0
0
0
0
0

0
0
0
0

0
0

0

0
0
0
0
0

0
0

0
0
0

0
0
0
O

03-10-99

TABLE OF CONTENTS

Section 1 SPECIFICATIONS

Introduction ............................................................................. 1 - l

1850/1855A Specifications ......................................................

1-2

Power Requirements & Physical Characteristics ..................... 1-3

1850 Block Diagram ................................................................ 1-4

1855A Block Diagram ............................................................. 1-5

Section 2

OPERATING INSTRUCTIONS,

CONTROLS AND INDICATORS

Front Panel ............................................................................... 2-1

Rear Panel ................................................................................ 2-4

New Features of 1850A and 1855A ......................................... 2-5

Oscilloscope Settings ............................................................... 2-6

Model 1850 Operation ............................................................. 2-7

Section 3 GENERAL OPERATING INFORMATION

Getting Started ......................................................................... 3-1

Power Connection ....................................................................

3-1

1855A Front Panel Operation .................................................. 3- I

Attenuator and Gain Operation ................................................ 3-1

Comparison Voltage Operation ............................................... 3-2

Differential Offset Operation ...................................................

3-3

Which Offset Mode Should Be Used? .....................................

3-4

Operator Traps to Avoid .......................................................... 3-4

1850A/1855A

1850A/1855A

INITIAL SCOPE AND 1855 SETUP

L_ .............

7----

’

........

~---

i ’

SELECT 50 OHM INPUT

OR

PROVIDE 60 OHM TERMINATOR

~,.~

50mV/I)fV

I

v ~.ImV/DIV

Posmo

"~’ SET SENSITMTY TO 50mVldiv

DURING OPgRA13ON. USE

ON LY 5OmvIoN ON

MORE SENSITIVE PosmoN$

POSITION TRACE TO CENTER <
SCREEN (DC OFFSET = OFF)

00 NOT USE TH E SCOPE

POSmON OR OFFSE’f

AFrER THIS INIT~L SETUP

~ AC

/

~, ’f oc

’~ o:

//,!

///’

@ SELECT DCINPUTCOUPLING

//

s

’ /

/

//

,/

CONNECT AMPLIFIER OUTPUT TO
SCOPE INPUT WITH 50 OHM COAX

~

.........

mE

LJ ~e~ ~ ~ ~

’ ’~’

--"~< "

/,

l g ] ATTACH XCl00 PROBES ~ ~’2"

DO NOT ADJUST PROBE COMPENSATION

~THOUT FIRST REFERRING TO THE MANUAL

TRACE ON ~COPE

USE VDIFF AND PVG TO POSITION

~i PVG DI|PLAYS THS VOLTAGE OF THE SIGNAL AS ff
PASSES THROUGH THE SCOPE DIEPLAY CENTERLIRE.

(RE~IRRED TO THE PROIE I~P)

CONNECT PROBE CODING LEAD TO
PROBE CODE INPUT ON 1866 REAR PANEL

ii

03116/99

e

o
o
i

i

e

e
e
e

o
o

e
e
e
e
e
o

o

e
o
e
o
e

o

o

o

i)

o
o
e
e
o
o

o
o
o
e

e
o

o
o
o

o

o

0

0
0

0

0

0

0
0
0

0
0

Specifications- 1850A/1855A

SECTION 1

SPECIFICATIONS

0
0

0
0

0

0
0
0
0
0

0
0
0

0
0
0

0

0
0
0
0

0
0

0
0

INTRODUCTION

The 1850A and 1855A are stand-alone high performance

100MHz differential amplifiers. They are intended to act

as signal conditioning preamplifiers for oscilloscopes, digi­tizers, network analyzers and spectrum analyzers, providing
differential measurement capability to instruments having

only a single-ended input. When used with an

1850A/1855A, most good quality oscilloscopes can obtain
Common Mode Rejection Ratio (CMRR) and overdrive
recovery performance that was previously unobtainable in

¯ any product.

Amplifier gain may be set to 1 or 10. A built-in input at­tenuator may be separately set to attenuate signals by a

factor of 10, allowing gains of 10, I, or 0.1 and common
mode dynamic range of_15.5V (+1) or +_.155V (+10).
tional probes increase the maximum input signal and com­mon mode ranges in proportion to their attenuation ratio,
but not exceeding their maximum input voltage rating.
Effective gain of the 1855A, including probe attenuation,
amplifier gain and attenuator settings, is automatically dis­played.

The 1855A has a bandwidth of 100 MHz, but any one of
the three 3-pole bandwidth limit filters may be selected to

reduce bandwidth to 20MHz, IMHz or 100kHz to limit
noise above the frequency of interest.

03/i 0/99

The 1850A/1855A output is carefully limited at +500mV
so that the oscilloscope is not overdriven by large inputs.
This allows many oscilloscopes to directly measure the
settling of D/A converters with 14 bit (60ppm) precision,
better than any other differential comparator.

The 1855A features a built-in Precision Voltage Generator
(PVG) that can be set to any voltage between +15.5 volts

(+10 volts in Differential Offset mode) with 100~tV resolu­tion. Each digit of the voltage generator output can be in­dividually incremented or decremented and the sign

changed between + and -. The PVG’s output can be se­lected as an input to the inverting (-) input of the amplifier
for operation as a differential comparator or applied inter-

nally as a true differential offset voltage. The voltage is
also available to be used externally through a rear panel

connector. On the 1850A, this connector becomes an input
through which the user can apply an external voltage to
achieve the same differential offset and comparison func-

tions.

The 1850A/1855A operates from 100 to 250 VAC line
without line switching.

High performance differential probes such as the Preamble
Instruments XC100 10X/100X high CMRR probes are rec-

ommended.

i-1

Specifications m 1850A/1855A

1850A/1855A SPECIFICATIONS

GENERAL:
Amplifier gain:

Gain accuracy:

Bandwidth:
Rise time:
Output impedance:

Intended output load:
Maximum output:
Input attenuation:
+10 ATTENUATOR accumc3.,:

Max differential linear input:

(X10 GAIN, +1 ATTENUATOR):
(X1 GAIN, +1 ATTENUATOR)
(X10 GAIN, +I0 ATTENUATOR)

(X1 GAIN, +10 ATTENUATOR)

Maximum input slew rate:

(+1 ATTENUATOR. X1 probe):
(+Ill ATTENUATOR or X10 probe):

(+10 ATTENUATOR and X10 probe):
(+1 ATTENUATOR and XI00 probe):

(+Ill ATTENUATOR and X100 probe):
Input noise (X10 GAIN):
DC drift (X10 GAIN):
Common mode rejection ratio:
Max common mode input:

(+1 ATTENUATOR):

(+Ill ATTENUATOR):

(+10 ATTENUATOR and X10 probe)
Input resistance:

(+1 ATTENUATOR. X1 or X10 GAIN):

(+10 ATTENUATOR. X1 or X10 GAIN):
Input capacitance (+1 or +10 ATTENUATOR):

Bandwidth limit filters (1855A only):

Filter characteristics ~ 1855A only):

+INPUT selections:

-INPUT selections:
Input coupling capacitor:

Input gate current (X1 and X10 GAIN, +1 ATTENUATOR):
Input protection:

DIFFERENTIAL OFFSET (VDIFF) MODE:

Differential offset range (referred to input):

(X10 GAIN, +I ATrENUATOR):

(X1 GAIN, +1 ATTENUATOR):
(XI0 GAIN, +10 ATTENUATOR):

(X1 GAIN, +10 ATTENUATOR):

(XI GAIN, +10 ATTENUATOR. X10 probe)

Differential offset accuracy:

(X10 GAIN, +I ATTENUATOR):

(X1 GAIN, +1 ATTENUATOR):
(X10 GAIN, +10 ATTENUATOR):

(XI GAIN, +10 ATTENUATOR):

1-2

1 orl0

+_1%

>I00MHz

<3.5ns
50 ohms
50 ohms

limited at +0.50V into 50 ohms

+1 or +10

_+0.05%

N).O5V or +0.5V with XIO probe

N).5 or +5.0V with XIO probe

_+0.5 or +-5.0V with XIO probe

_+5.0 or +50V with XIO probe

O. 5 V/ns

5.0V/ns
50V/ns

50V/ns

500V/ns

<4nV/sq rt Hz. broadband

50~V/°C

See Figure 1-1

+15.5V (X1 or X10 GAIN)

+-I55V(X1 or X10 GAIN)

+l.55kV(Xl or X10 GAIN)

1 megohm or 100 megohms

1 megohm

20pF

20MHz. 1.0MHz and 100kHz

18dB/octave (3-pole Bessel)

AC, OFF (Pmtegra),

AC, OFF (precharge), DC, Vco~

0.1 ~tF, 400VDC
<10pA. 0-45°C

protected to +_250V, automatic input disconnect with

manual reset

+-lV
+IOV
+-IOV

+lOOV

+l.OkV

0.1% + 50V

0.1% + 500V

0.15% + 500V

0.15% + 5mV
03/10/99

0
0
0

0
0

0
0

0
0
0

0
0
0

0

0

0
0
0
0
0
0

0
0

0
0
0
0

0
0

0
0
0

0
0

0
0
0
0

0
0
0

0
0
0

COMPARISON OFFSET (Vco~tp) MODE:
Effective comparison voltage range:

(+1 ATTENUATOR):
(+10 ATTENUATOR):

(Xl0 probe and +10 ATTENUATOR):

PRECISION VOLTAGE SOURCE (1855A only):
Output range:

DC accuracy:
Resolution:
Control:
Temperature coefficient:

Type:

Output:
PVG AUTO ZERO:

POWER REQUIREMENTS

Line voltage requirement:
Line frequency range:
Power requirement:

ENVIRONMENTAL CHARACTERISTICS
Operating Range:
Non-Operating:

PHYSICAL CHARACTERISTICS
Height:

Width:
Depth:
Weight:
Shipping Weight:

Specifications- 1850A/1855A

’_15.5V (Xl or Xl0 GAIN)

+155V (Xl or Xl0 GAIN)

1.55kV (Xl or Xl0 GAIN)

+15.5V

0.05% of reading +500~V (0° to 50°C)
100~tV

All digits are addressable. Digit carries to next decade

typically <5ppm/°C of full scale

Oven stabilized buried Zener

Applied to inverting input and available at rear panel

Sets output to zero when 0.0 volts selected and
in error by more than 0.5mV thereafter

100 to 250VAC

48 - 66Hz

35 W maximum

0 to 50°C

-40 to 75°C

7,29cm (2.87")

21.2cm (8.36")

23.2cm (9.12")

2.15kg (4.751b)

3.12kg (6.881b)

c
M
R
R

1000000

100000

~-- i
I

i.

1000~

1000

i

100 :

i ,

’ i

i

|0 I

I

AMPLIF’IER SE’I’T1NGS

t

XI OR Xl0 GAIN. XI Aq~’ENUATOR L

1 RHz

10 kHz 100 kHz

1 MHz 10 MHz

100 MHz

Figure 1-1. CMRR vs Frequency

1131111199

1-3

1-4

Specifications ~ 1850A/1855A

03110199

O
O
O
O

O

O

O

O

O

O

O
O
0

O

O

O

O

O

O
0
O

O

|

O
O
O

O

e

O

II

O