SIM910/911 JFET & BJT Voltage Preamplifiers0 pages

Small Instrumentation Modules
SIM910 and SIM911 — Low noise voltage preamplifiers
· 4 nV/√Hz input noise (SIM910)
· 1.8 nV/√Hz input noise (SIM911)
· Low output noise
· 1 MHz bandwidth
· Selectable gain from 1 to 100
· AC or DC coupled
· Differential or single-ended input
· 85 dB CMRR
· SIM910 ... $975 (U.S. list)
· SIM911 ... $975 (U.S. list)
SIM910 JFET and SIM911 BJT Voltage Preamplifiers
The SIM910 and SIM911 are low-noise, programmable
preamplifiers which are ideal for a wide range of small signal
applications. The primary differences between the two models
are their input impedance and input noise. The SIM911 has a
bipolar junction transistor front-end, offers lower input noise,
and has a 100 kΩ front-end impedance. The low bias current
and 100 MΩ input impedance of the SIM910, which has a
JFET front-end, make it a better choice for use with high
impedance sources.
Both modules maintain very low output noise resulting in
exceptional overall noise performance—even at low gain
levels. The bandwidth of these preamplifiers is independent of
gain setting so waveforms do not change shape as the gain is
varied. Dual parallel outputs (one front and one rear) provide
flexibility in cabling.
or DC coupled. Additionally, the BNC input shields can be
floated, avoiding spurious ground loops when measuring
remote signals.
The digital control circuitry in the SIM910/911 is designed
with a special clock-stopping architecture in which the
microcontroller is turned on only when settings are being
changed. This guarantees that no digital noise can contaminate
low-level analog signals. Settings may be changed from the
front panel or through the remote interface. All instrument
settings can also be queried via the remote interface. The
module generates a status signal to alert the user of an
overload condition. Both the SIM910 and SIM911 can be
operated outside the SIM mainframe by powering them with
their required DC voltages.
Inputs can be configured as differential (A – B), singleended (A), or internally grounded, and can be either AC
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