How to design a diplexer having wide differance in BW of TX and RX filter

[ambrish_ghadiya]

I want to design a diplexer having wide differance in BW of TX and RX filter.
For example RX filter BW=32 MHz and TX filter BW=450MHz. and separation band=20MHz.
One problem I am getting is the F0 of diplexer, i.e., it is falling in band of TX filter. If this is the case then how to synthesis such diplexer??

 

[bubuta77]

For which frequencies do you design? Anyway a separation of 20MHz, i guess only cavity diplexer can handle and if these a case probably easier to buy customized one.

 

[biff44]

You do not mention the carrier frequency, which is critical for filter Q reasons. But if the carrier frequency is low enough, I might do a lowpass/highpass elliptical diplexer, and follow up with bandpass filtering stages if more rejection is needed.

 

[vfone]

Referring to your last question:

"One problem I am getting is the F0 of diplexer, i.e., it is falling in band of TX filter. If this is the case then how to synthesis such diplexer??"

...this is not a diplexer anymore...

 

[Phytech]

I guess what you need is a switched filter bank instead of a diplexer.