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Atec Stanford-Research-SR810-SR830 User Manual

Digital lock-in amplifiers

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phone: (408)744-9040

www.thinkSRS.com

Stanford Research Systems

· 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)

· Auto-gain, -phase, -reserve and -offset

· Synthesized reference source

· GPIB and RS-232 interfaces

· SR810 ... $3850

(U.S. list)

· SR830 ... $4750

(U.S. list)

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 drift-

free dynamic reserve.

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 10

6

and 10

8

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 lock-

ins 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.

Extended Dynamic Reserve

The dynamic reserve of a lock-in amplifier, at a given full-

scale input voltage, is the ratio (in dB) of the largest interfering

SR810 & SR830 DSP Lock-In Amplifiers

Digital Lock-In Amplifiers

SR810 and SR830 — DSP lock-in amplifiers

SR830 DSP Lock-In Amplifier