How does a Gilbert cell drive polyphase filter?

[pugongying]

output impedance polyphase filter

The Gilbert mixer has resistor load.(400ohm)
Does the polyphase filter affect the linearity of the mixer?
does the polyphase filter requires a low output impedance buffer?

 

[rfsystem]

Could you answer how you build up the polyphase filter? Is it active or passive? For low IF or radio frequency?

 

[pugongying]

passive RC polyphase filter

low-IF, IF=4MHz,signal BW=2MHz

Thx