Silly projects -> A simple complicated Radio with FPGA

This is an old idea that I keep recycling in my brain (what's left of it) - to build a simple radio made of two major components (two PCBs) - an analog front end and a digital processing board (the Spartan7 FPGA board that I designed previously)

So brace yourself for a series of unfortunate events and silly mistakes that I'm going to make along the way. I will publish everything with good and bad with the obvious risk to look like a fool (I got to a stage in life when I don't care so much about the world)

Back to hardware

The aim is to make a fairly modern radio with most of the demodulation and filtering in digital domain, with an incorporated spectrum analyzer (HDMI display) and simple controls (probably a Gamepad) - the audio output will be on amp+ speaker external to the FPGA board. (a PMOD module)

The analog front end is going to be simple at the beginning aiming for just a few HAM Radio bands (40m, 20m and ...will see) - I'll keep this part simple antenna connector, some pre filtering, a mixer to down convert - a VGA (variable gain amp) am anti-alias filter and an inexpensive 14 bit ADC.

The first iteration is going to be more for evaluating the parts that I have in mind (and trying to correct the mistakes as I go along.

The input filter is going to designed using an online calculator and I'll detail the construction in a separate video / blog post, will be followed by a passive mixer (diodes) and a fixed gain amplifier (transistors) followed by a programmable gain amplifier.

Frontend block diagram - Analog in Blue, Digital in Red

Parts that I have I mind for the VGA are MAX9939 ( will see how it goes) https://www.analog.com/media/en/technical-documentation/data-sheets/MAX9939.pdf

for the ADC I ordered a LTC2314-14 but I'm still evaluating this decision.

https://www.analog.com/media/en/technical-documentation/data-sheets/231414fa.pdf

Just plans on back of napkin...right now.