testing a direct IF rec linearity - receiver spurs

[zeshan102]

Receiver Spurs

I am testing a direct IF rec linearity and out is quite linear to input power but spurs start to apear even 6 dB before the compression point which stage is saturating before

 

[Abhishekabs]

Receiver Spurs

Is it due to insufficient shielding?
try covering your receiver circuit with some metallic body and check.

 

[kspalla]

Receiver Spurs

Is spur not appearing at lower inputs?
Which point you are measuring?
Explain the schematic.

 

[zeshan102]

Re: Receiver Spurs

I cannot do anything about sheiding beacuse its chip but i can vary the power supply of different stage in IC by programing like supply to IF filter LNA and LO so which can effect most to reduce these spurs.

I am measuring at I Q before ADC and yes when input is low spurs didnt seems to appear

 

[kspalla]

Receiver Spurs

Will you explain the block diagram?
May I know the reason for IF filter having supply?