LMS RX PLL questions

Sylvain Munaut 246tnt at gmail.com
Wed Feb 6 20:53:27 UTC 2013


Hi,

I have a couple questions about the RX PLL in the LMS chip:

 - What are the various LOBUF  for ? (1/2/3). Do they correspond the
the 3 input of the RX side ? I see they're controlled by the SELOUT
bits, but I have no idea how to choose. Should it be matched to
LNASEL_RXFE ?

 - What's the expected levels of the LO harmonics ?  In my tests I see
to measure around -10 dB for 3xLO and ~ -22 dB for 5x LO. Is there any
way to improve this ?

   The method I used to measure is to feed 400 MHz narrow bw signal to
the input. Tune LMS to 400 MHz and measure the received strength, then
change the signal generator to TX a signal at 1.2 GHz and measure
again, then at 2GHz, and so on ...


Cheers,

    Sylvain




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