SR810/830 DSP Lock-In Amplifiers0 pages

Digital Lock-In Amplifiers
SR810 and SR830 — DSP lock-in amplifiers

SR830 DSP Lock-In Amplifier

SR810 & SR830 DSP Lock-In Amplifiers
The SR810 and SR830 DSP Lock-In Amplifiers provide high
performance at a reasonable cost. The SR830 simultaneously
displays the magnitude and phase of a signal, while the SR810
displays the magnitude only. Both instruments use digital
signal processing (DSP) to replace the demodulators, output
filters, and amplifiers found in conventional lock-ins. The
SR810 and SR830 provide uncompromised performance with
an operating range of 1 mHz to 102 kHz and 100 dB of driftfree dynamic reserve.

· 1 mHz to 102.4 kHz frequency range
· >100 dB dynamic reserve
· 5 ppm/°C stability
· 0.01 degree phase resolution
· Time constants from 10 µs to 30 ks
(up to 24 dB/oct rolloff)

Input Channel
The SR810 and SR830 have differential inputs with 6 nV/√Hz
input noise. The input impedance is 10 MΩ, and minimum
full-scale input voltage sensitivity is 2 nV. The inputs can
also be configured for current measurements with selectable
current gains of 106 and 108 V/A. A line filter (50 Hz or
60 Hz) and a 2× line filter (100 Hz or 120 Hz) are provided
to eliminate line related interference. However, unlike
conventional lock-in amplifiers, no tracking band-pass filter
is needed at the input. This filter is used by conventional lockins to increase dynamic reserve. Unfortunately, band pass
filters also introduce noise, amplitude and phase error, and
drift. The DSP design of these lock-ins has such inherently
large dynamic reserve that no band pass filter is needed.

· Auto-gain, -phase, -reserve and -offset
· Synthesized reference source
· GPIB and RS-232 interfaces

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· SR810 ... $4150 (U.S. list)

Extended Dynamic Reserve

· SR830 ... $4950 (U.S. list)

Stanford Research Systemstt
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The dynamic reserve of a lock-in amplifier, at a given fullscale input voltage, is the ratio (in dB) of the largest interfering

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