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Problem in generating IF using SA612A mixer

Question asked by SANKET PATEL on Jul 25, 2016

Hi! Greetings!


I am new to NXP community. I have started working on SA612A mixer. Since few days, I have been struggling in generating IF (KHz) output.


NXP SA612A pin description (A quick reference so that you don't have to refer to the datasheet):

Pin1,2: differential RF input pins

Pin3: Ground

Pin4,5: differential IF output pins

Pin6,7: LO differential input

Pin8: +5V

My circuit configuration and problem detail:

  • 44.94MHz RF applied to pin1 through DC blocking capacitor. Pin2 is grounded via capacitor. RF signal level on pin1 is: <-15dBm (200mV peak to peak into 1.5kOhm input resistance of SA612) (<-15dBm ensures linear operating range considering IIP3)
  • 44.88MHz LO applied to pin 6, pin7 left open as suggested in datasheet/ application note:AN1993. LO level on pin6 is: 230mV peak to peak (as per datasheet, it has to be 200mV to 300mV peak to peak)
  • Expecting to see 60Kz output (difference frequency) peak in the spectrum analyzer.

60KHz signal seems totally immersed in the noise, not a peak at all, what can be the reason? Tried with other frequencies as well.

Please share your views on this.