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SR570 Low-Noise Current Amplifier

SR570 Low-Noise Current Amplifier
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Low-Noise Current Preamplifier SR570 — DC to 1 MHz current preamplifier SR570 Current Preamplifier The SR570 is a low-noise current preamplifier capable of current gains as large as 1 pA/V. High gain and bandwidth, low noise, and many convenient features make the SR570 ideal for a variety of photonic, low-temperature and other measurements. · 5 fA/√ Hz input noise · 1 MHz maximum bandwidth · 1 pA/V maximum gain · Adjustable bias voltage The SR570 has sensitivity settings from 1 pA/V to 1 mA/V that can be selected in a 1-2-5 sequence. A vernier gain adjustment is also provided that lets you select any sensitivity in between. · Two configurable signal filters · Variable input offset current Gain can be allocated to various stages of the amplifier to optimize the instrument’s performance. The low-noise mode places gain in the front end of the amplifier for the best noise performance. The high-bandwidth mode allocates gain to the later stages of the amplifier to improve the frequency response of the front end. In the low-drift mode, the input amplifier is replaced with a very low input-current op amp, reducing the instrument’s DC drift by a factor of 1000. · Line or battery operation · RS-232 interface Filters The SR570 contains two first-order RC filters whose cutoff frequency and type can be configured from the front panel. Together, the filters can be configured as a 6 or 12 dB/oct rolloff low-pass or high-pass filter, or as a 6 dB/oct rolloff band-pass filter. Cutoff frequencies are adjustable from 0.03 Hz to 1 MHz in a 1-3-10 sequence. A filter reset button Stanford Research Systems

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is included to shorten the overload recovery time of the instrument when long filter time constants are used. Input Offset and DC Bias An input offset-current adjustment is provided to suppress any unwanted DC background currents. Offset currents can be specified from ±1 pA to ±1 mA in roughly 0.1 % increments. The SR570 also has an adjustable input DC bias voltage (±5 V) that allows you to directly sink current into a virtual null (analog ground) or a selected DC bias. Toggle and Blanking Two rear-panel opto-isolated TTL inputs provide additional control of the SR570. A blanking input lets...

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High Bandwidth Mode 10-9 Current Noise (Amps/√Hz) Current Noise (Amps/√Hz) Noise vs. frequency plots High Bandwidth Mode 1 Gain / Nominal Gain (dB) Gain / Nominal Gain (dB) Gain vs. frequency plots Stanford Research Systems

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Inputs Virtual null or user-set bias (±5 V) Input offset ±1 pA to ±1 mA adjustable DC offset current Maximum input ±5 mA Noise See graphs on previous page Sensitivity 1 pA/V to 1 mA/V in 1-2-5 sequence (Vernier adjustment in 0.5 % steps) Frequency response ±0.5 dB to 1 MHz (Adjustable front-panel frequency response compensation for source capacitance) Grounding Amplifier ground is fully floating. Amplifier and chassis ground are available at rear panel. Input ground can float up to ±40 V. Gain accuracy DC drift Maximum output Filters Signal filters Gain allocation Low Noise High Bandwidth...

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