My demo board is the FMComm3 for evaluation and it came with a 40MHz clock. My question is with an external TCXO of 50MHz, what are the setting in the application software to get the back the frequency TX output including the internal LO when we use it with a 40MHz internal clock?
For instant, when I connected a 50MHz external lock and with a TX frequency setting of 1GHz output, I got 25% higher which is 1.25GHz, and this is correct since 50MHz is 25% higher than 40MHz. How can I re tune using this application so I can get back to the 1GHz with the 50MHz external clock or generally speaking to get back the 25% frequency shift due to the 50MHz clock?
Usually with a PLL source, some companies including AD provide also an application so we can change the reference clock and recalculate the divider to get the right frequency output. Below is the reference paper on how to re tune the chip using external clock but I didn't succeed.