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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 frontand one rear) provide flexibility in cabling.
Inputs can be configured as differential (A-B),
single-ended (A), or internally grounded, and can be either AC 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.
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