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).
Re: how to design a IF input stage for superheterodyne recei
An option is to use a diplexer placed after the mixer, followed by the LC BPF.
The LC BPF shall be matched on 50 ohms on both sides, to optimize for a low in-band ripple and low insertion loss.
The first IF stage will be also matched for 50 ohms at its input.
Re: how to design a IF input stage for superheterodyne recei
Whatever frequency is used a resistive matching introduce the same noise figure degradation.
A reactive matching network (LC) will introduce minimal losses.