These are my notes about the Meteor Radiometer. The first goal was to recreate what was done before: A raspberrypi 4 + WaveAhare high resolution AD and DA converter board + the amplifier based on BPW34 pin diode and LMC6464 quad opamp as described in this paper: 2018_WGN_Radiometer-final.pdf.
WaveShare High-Precision AD/DA Board:
https://www.waveshare.com/high-precision-ad-da-board.htm
https://www.waveshare.com/wiki/High-Precision_AD/DA_Board
The ADC part of the board is based on the ADS1256 from TI:
https://www.ti.com/product/ADS1256
https://www.ti.com/lit/gpn/ads1256
The amplifier is based on the LMC6464 and the BPW34:
https://www.ti.com/product/LMC6464
https://www.ti.com/lit/gpn/lmc6464
Vishay: https://www.vishay.com/docs/81521/bpw34.pdf
OSRAM: https://dammedia.osram.info/media/resource/hires/osram-dam-5488305/BPW%2034_EN.pdf
The amplifiers are setup as a high-sensitivty current to voltage converter.
high_sensitivity_I2V.png
Where: Vout = (-Req) * Iin and Req = (1 + R2/R1 + R2/R3) * R1
When R1 = 1M, and R2,R3 = 10k this will give a 2.01V/1uA
(Source: "Design with Operational Amplifiers and Analog Intergated Circuits" by Sergio Franco)