2m QSD PMOD
The board is designed for experimenting with an all-digital SERDES-based quadrature sampling detector (QSD) and quadrature modulator.
This is a PMOD for differential (balanced) to/from single-ended (unbalanced) I/O. It has a 4:1 balun to match the 200 Ohm impedance of the PMOD to the 50 Ohm SMA.
The center tap on the balun is biased at VDD/2.
The board includes a 4-pole band-pass filter centered around the 2m amateur radio band. It is a Chebyshev filter with 1dB ripple in the passband. It is designed to both be an anti-aliasing filter and to suppress the commercial FM radio band.
This repo contains KiCAD files and Gerbers for those wanting to make their own boards.
An interactive BOM is available.
This project is OSHW (Open Source Hardware), released under the GPLv3 license.