Stanford SR830 Lock In Amplifier Digital Signal Processor
Condition: Refurbished / Calibrated
Warranty: 1 YEAR WARRANTY
Stanford Research Systems SR830 Lock-In Amplifier
The SR810 Lock-In Amplifier and SR830 Lock-In Amplifier provide high performance at a reasonable cost. The SR830 simultaneously displays the magnitude and phase of a signal, while the SR810 displays 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 Lock-In Amplifiers 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 input 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 lock-ins to increase dynamic reserve. Unfortunately, band pass filters also introduce noise, amplitude and phase error, and drift. The DSP based design of these lock-ins has such inherently large dynamic reserve that no tracking 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 signal to the full-scale
input voltage. The largest interfering signal is defined as the amplitude of the
largest signal at any frequency that can be applied to the input before the
lock-in cannot measure a signal with its specified accuracy.
Conventional lock-in amplifiers use an analog demodulator to mix an input signal
with a reference signal. Dynamic reserve is limited to about 60 dB, and these
instruments suffer from poor stability, output drift, and excessive gain and
phase error. Demodulation in the SR810 Lock-In Amplifier and SR830 Lock-In
Amplifier is accomplished by sampling the input signal with a high-precision A/D
converter, and multiplying the digitized input by a synthesized reference
signal. This digital demodulation technique results in more than 100 dB of true
dynamic reserve (no prefiltering) and is free of the errors associated with
analog instruments.
Digital Filtering
The digital signal processor also handles the task of output filtering, allowing time constants from 10 µsec to 30,000 s, with a choice of 6, 12, 18 and 24 dB/oct rolloff. For low frequency measurements (below 200 Hz), synchronous filters can be engaged to notch out multiples of the reference frequency. Since the harmonics of the reference have been eliminated (notably 2F), effective output filtering can be achieved with much shorter time constants.
Digital Phase Shifting
Analog phase shifting circuits have also been replaced with a DSP calculation. Phase is measured with 0.01° resolution, and the X and Y outputs are orthogonal to 0.001°.
Frequency Synthesizer
The built-in direct digital synthesis (DDS) source generates a very low distortion (-80 dBc) reference signal. Single frequency sine waves can be generated from 1 mHz to 102 kHz with 4½ digits of resolution. Both frequency and amplitude can be set from the front panel or from a computer. When using an external reference, the synthesized source is phase locked to the reference signal.
Auto Functions
Auto-functions allow parameters that are frequently adjusted to automatically be set by the instrument. Gain, phase, offset and dynamic reserve are each quickly optimized with a single key press. The offset and expand features are useful when examining small fluctuations in a measurement. The input signal is quickly nulled with the auto-offset function, and resolution is increased by expanding around the relative value by up to 100×. Harmonic detection is no longer limited to only the 2F component. Any harmonic (2F, 3F, ... nF) up to 102 kHz can now be measured without changing the reference frequency.
Analog Inputs and Outputs
Both instruments have a user-defined output for measuring X, R, X-noise, Aux 1, Aux 2, or the ratio of the input signal to an external voltage. The SR830 has a second, user-defined output that measures Y, Θ, Y-noise, Aux 3, Aux 4 or ratio. The SR810 and SR830 both have X and Y analog outputs (rear panel) that are updated at 256 kHz. Four auxiliary inputs (16-bit ADCs) are provided for general purpose use—like normalizing the input to source intensity fluctuations. Four programmable outputs (16-bit DACs) provide voltages from -10.5 V to +10.5 V and are settable via the front panel or computer interfaces.
Specifications:
| Signal Channel | |
| Voltage inputs | Single-ended (A) or differential (A-B). |
| Current input | 10^6 or 10^8 Volts/Amp |
| Full scale sensitivity | 2 nV to 1 V in a 1-2-5-10 sequence (expand off). |
| Input impedance | Voltage: 10 MW+25 pF, AC or DC coupled. Current: 1 kW to virtual ground. |
| Gain accuracy | ±1% from 20°C to 30°C (notch filters off), ±0.2 % Typical. |
| Input noise | 6 nV/ÖHz at 1 kHz (typical) |
| Signal filters | 60 (50) Hz and 120(100) Hz notch filters (Q=4) |
| CMRR | 100 dB to10 kHz (DC Coupled), decreasing by 6db/octave above 10 kHz |
| Dynamic Reserve | Greater than 100 dB (with no signal filters) |
| Harmonic Distortion | -80 dB |
| Reference Channel | |
| Frequency Range | 1 mHz to 102 kHz |
| Reference input | TTL (rising or falling edge) or Sine. Sine input is1 MW, AC coupled (>1 Hz). 400 mV pk-pk minimum signal. |
| Phase resolution | 0.01° |
| Absolute phase error | <1° |
| Relative phase error | <0.01° |
| Orthogonality | 90° ± 0.001° |
| Phase noise | External synthesized reference: 0.005° rms at 1 kHz, 100 ms, 12 dB/oct. Internal reference: crystal synthesized, <0.0001° rms at 1 kHz |
| Phase drift | <0.01°/°C below 10 kHz <0.1°/°C to 100 kHz |
| Harmonic detect | Detect at Nxf where N<19999 and Nxf<102 kHz. |
| Acquisition time | (2 cycles + 5 ms) or 40 ms, whichever is greater |
| Demodulator | |
| Zero stability | Digital displays have no zero drift on all dynamic reserves. Analog outputs: <5 ppm/°C for all dynamic reserves |
| Time constants | 10 µs to 30 s (reference > 200 Hz). 6, 12, 18, 24 dB/oct rolloff. up
to 30000 s (reference < 200 Hz). 6, 12, 18, 24 dB/oct rolloff Synchronous filtering available below 200 Hz |
| Harmonic rejection | -80 dB |
| Internal oscillator | |
| Frequency | 1 mHz to 102 kHz |
| Frequency accuracy | 25 ppm + 30 µHz |
| Frequency resolution | 4 1/2 digits or 0.1 mHz, whichever is greater |
| Distortion | f<10 kHz, below -80 dBc. f>10 kHz, below -70 dBc.1 Vrms amplitude |
| Output impedance | 50 Ohm |
| Amplitude | 4 mVrms to 5 Vrms (into a high impedance load) with 2 mV resolution. (2 mVrms to 2.5 Vrms into 50W load) |
| Amplitude accuracy | 1% |
| Amplitude stability | 50 ppm/°C |
| Outputs | Sine output on front panel. TTL sync output on rear panel. When using an external reference, both outputs are phase locked to the external reference. |
| General | |
| Interfaces | IEEE-488 and RS232 interfaces standard. All instrument functions can be controlled through the IEEE-488 and RS232 interfaces. |
| Preamp power | Power connector for SR550 and SR552 preamplifiers |
| Power | 40 Watts, 100/120/220/240 VAC, 50/60 Hz |
| Dimensions | 17"W x 5.25"H x 19.5"D |
| Weight | 30 lbs. |
Stanford Research Systems SR830 Lock In Amplifier
Provides uncompromised performance with an operating range of 1 mHz to 102 kHz and 100 dB of drift-free dynamic reserve
Includes Accesories As Listed
SR 830 SR-830
Stanford SR830 SR-830 Lock In Amplifier Models On Sale Warranty Calibration Backed by The Best Service and Lowest Prices in the Industry.
BC# 43528-L/T*
- Stanford Research Systems SR830 Lock In Amplifier (BC# 43528-L/T*)
- Power Cord
- User Manual On CD-ROM