I've found many frequency doublers that work in the MHz range but having trouble finding any for KHz frequencies. I need to take a signal produced from some digital electronics and double the frequency of this signal. Where might I find such a device?
The signal I want to double the frequency of looks like so:
I have thus-far been using an FPGA to read in the signal, remove the DC offset and then squaring the value in order to frequency double it, but the DC offset varies significantly and results in the output signal being not a precise frequency doubling and occasionally outputting at the frequency rather than doubling it.
The power spectral density of this signal looks like so:
Best Answer
You can easily do it with your FPGA, no extra hardware is needed.
If you already have a working FPGA method for a fixed DC offset, you can allow the DC offset to be variable by using something called a "leaking integrator": From each sample s subtract a variable offset v. Modify the value of v for each sample by increasing v by one when s is positive and decreading v by one when s is negative. That way the value of v follows the changing DC offset and what remains after the subtraction is the AC component of the signal. Then you can square that signal.
[Edit] Lol, it's been so many years since I was in the university, I had to reassure myself that square of sine is in fact twice the frequency... which of course it is. :)