Lab equipment/fMCG photoamplifier 0.1

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Differential photo amplifier with a single sided output

Description

The main purpose of this board is to measure the polarization rotation signal in magnetometer experiments. The board provides differential and single sided signals, so that the rotation angle can be measured, and the common noise can be cancelled when the polarimeter is not perfectly balanced.

This photo amplifier design is based on the transimpedance amplifier from Hobbs book (Building Electro-Optical Systems, Making It All Work, Second Edition, Ch. 18 - Front ends) and Brian Patton's design for a photo amplifier with single-sided outputs. The bandwidth of this board is 20 kHz, but can be increased well beyond that by changing the RC constants in the feedback of the opamps.

TODO

  • Smaller power connector
  • Label +, GND, - on the power connector

Schematics

BOM and assembly

Noise, gain, phase caclulations

Mike calculated what is the noise of the board at the photocurrents we are measuring (~2 uA). They are well below the shot noise limit within the bandwidth.

Eagle design

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