Introduction To The Instrument - Stanford Research Systems SIM983 Operation And Service Manual

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1.1 Introduction to the Instrument

remote interface
DC accuracy
AC performance
Input BNC 1 kΩ
input protection
1.00 MΩ
High-impedance buffer
Programmable offset
The SIM983 Scaling Amplifier provides fine adjustable gain and
o set control of an analog signal. The gain (0 01
its polarity (inverting or non-inverting), and the o set voltage
( 10 00 V V 10 00 V) can be set from either the front panel
ofs
or remotely. A remote computer can access the module through the
SIM900 Mainframe, using RS–232 or GPIB.
The digital control circuitry in the SIM983 is designed with a special
clock-stopping architecture. The microcontroller is turned on only
when the polarity, gain, or o set are being changed, during remote
communications, or when an overload condition occurs. This guar-
antees that no digital noise contaminates low-level analog signals.
A user-commanded autocalibration procedure allows one to control
the input-referred o set to within 1 mV of the desired value.
The amplifier's high slew rate allows it to output a 10 V peak-peak
sine wave at a frequency of 1 MHz. The gain stage of the amplifier
is compensated in a flexible fashion to provide a sensible pulse re-
sponse, so the bandwidth of the instrument is adjusted according to
1
its gain. The ample output current in the SIM983 permits one to
drive a 50 load.
If the maximum input voltage is exceeded, or the gain or o set cause
the output voltage to exceed its maximum, the appropriate overload
LED turns on. If armed, the module also generates a status signal to
alert the user of the overload condition. The SIM983 can be operated
outside the SIM900 Mainframe by powering it with its required DC
voltages.
A block diagram of the amplifier is shown below in Figure 1.1.
Invert non-
inverting
polarity
inverting
polarity
Figure 1.1: The SIM983 block diagram.
1
The gain-bandwidth product changes with the gain.
frequency
compensation
37 Ω
Programmable gain
(inverting)
SIM983 Scaling Amplifier
Getting Started
G 19 99),
Output BNC,
rear
13 Ω
Output BNC,
front
13 Ω