I posted following query to NXP "Wireless Connectivity" discussion portal. I am not sure if it was appropriate place for my question. Hence posting it again here (in "other NXP solutions". Hopefully it covers RF too). Please go through it.
I have started working on SA612A mixer. Since many 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
Pin4,5: differential IF output pins
Pin6,7: LO differential input
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) (at later stage I decreased the RF power further to 20mV rms, to make it operate in linear range)
- 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) (at later stage I also went for 224mV rms LO input)
- 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.