Hi all,

I am simulating the vco, polyphase and passive mixer together.

I have an output amplitude 1.75Vpp from vco, after the polyphase filter,
it becomes 800mVpp. But when I connect this output to mixer, it becomes
340mVpp which is not enough to drive mixer.

It seems that a isolation amplifier would be useful placed between
polyphase filter and mixer. But I am not sure how to build this kind of
large input signal and high speed amplifier or I should use just a LC tank
network to amplify the signal?

Could you please give me some suggestions? Thank you vey much.