Generate second LO from main LO

[Ghost Tweaker]

Hi everyone,

I have a pretty basic question. I'm designing a wireless receiver (discrete design on a PCB) and have at disposal a first local oscillator frequency in the 1-2GHz range, generated by a VCO. Now I need a second local oscillator freqency in the 50-100MHz. Do you guys have any recommendation on how to generate this? Currently I would use a divide by N component but these usually generate an awfull square signal and the N value is usually limited to a very narrow set of values...

Do you guys have any other methos to proceed?

Thanx in advance

 

[biff44]

1) you can multiply the clock frequency up to be the 2nd lo
2) you can have a 2nd pll at 50 MHz
3) can take you digital clock frequency, bandpass filter it to get one of the odd harmonics, bandpass filter it, amplify it, and there you are with a sine wave
4) You can use an identical 1st and 2nd lo, although your 1st IF will be around 1 Ghz instead of 50 MHz
5) You can just use the 50 MHz IF and oversample it with an adc aliasing the frequency
6) you can just use the 50 MHz IF and do your demodulation there
7) you can injection lock or phase lock a 50 MHz VCO onto the divided down 50 MHz signal
8) you can just filter the heck out of the 50 MHz signal. All you would need to do is perhaps a 7 pole lowpass filter, and the cuttoff frequency would not be too sensitive.
9) you could run the divided down 50 MHz thru a loosely coupled regenerative amplifier tuned to 50 MHz and strip off the harmonics.

 

[Ghost Tweaker]

Thank you this is what we call beeing complete! I think I will use either a second VCO either a divide by N and filter the square signal...

 

[davicente]

AS i can remember, you could use two different mixers with just one vco:

-a second armonic mixer
-the usual mixer

Added after 4 minutes:

AS i can remember, you could use two different mixers with just one vco:

-a second armonic mixer
-the usual mixer

Added after 4 minutes:

AS i can remember, you could use two different mixers with just one vco:

-a second armonic mixer
-the usual mixer