I am very new to PCB design and have recently completed schematic capture and PCB layout of an optical detection circuit using Altium Designer. My custom PCB consists of a photodiode, transimpedance op amp, 13-bit ADC, and bypass capacitors. This PCB is to be mounted on top of the Arduino Micro via the 17-pin headers, and will interface with the ADC using SPI protocol.
My two questions are:
- Are there any evident errors with the PCB layout?
- Are there any evident improvements I can make to the schematic to improve the noise performance?
The current system follows the flow of:
( Photodiode -> Transimpedance Op Amp -> 13-Bit ADC ) -> Arduino Micro -> PC
- Bandwidth: 112kHz
- 5V Supply to ADC and Op Amp
PCB Specifications (Edited):
- 2 layer stack
- Entire bottom layer is a GND plane (polygon pour) that combines analog GND and digital GND (GND traces are 20mils)
- Within the bottom layer, I have +5V signal traces (25mils) and sensor signal traces (20mils)
- On the top layer, I have SPI communication lines (20mils)
- Board dimensions: 48mm x 18mm
- Photodiode: https://www.vishay.com/docs/81519/bpw21r.pdf
- Op Amp: https://www.digikey.ca/en/products/detail/texas-instruments/LMP7717MAE-NOPB/2092434
- ADC: https://ww1.microchip.com/downloads/en/DeviceDoc/21697F.pdf
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