who can tell me how to design a IF input stage for superheterodyne receiver
the IF frequency is about 180MHZ,and followed by external LC BPF.
as i known, the IF LC BPF must be match with IF input stage,but i don't know how to design it.(if the BPF matched resister is low, is it necessary to design a COMMOM GATE(CG) stage to match the LC BPF? or directly Gate input?(CS).

mydreamhouse wrote on Feb 24^th, 2009, 8:35am:
mydreamhouse wrote on Feb 27^th, 2009, 2:58am:

Your question is too lack of information, so no one can answer.

This is very true for all your posts too.
http://www.designers-guide.org/Forum/YaBB.pl?num=1235494642/0#0
http://www.designers-guide.org/Forum/YaBB.pl?num=1229879167/0#0

If you want someone to answer your post, you have to describe your questions regarding situation and condition in detail using industrial standard terminologies.

mydreamhouse wrote on Feb 24^th, 2009, 8:35am:

If your system is very narrow band system, you can use simple resonator as BPF here high impedance of next input stage is required.
Here you might be able to use impedance of next input as part of BPF.

Even though you design formal filters, there are three variations,
(1) R-R Type
(2) R-infinite Type
(3) 0-R Type

You seem to know only (1).

And for BPF design, resonator coupled structure is preferable than formal filter design.

mydreamhouse wrote on Feb 27^th, 2009, 9:14am:

Output Stage Impedance ----> Load Impedance of Drain Output or Impedance inserted to Source Output
Input Stage Impedance ----> Impedance terminated at Gate Input or Impedance inserted to Source Input

These options depend on requirements for Gain, Distortion, Noise characteristics and termination impedance value of filter.