steven_l
Member level 1
i am dedsigning a mixer for a Superheterodyn receiver .
The input signal is wideband from tens of MHz to tens of hundreds of MHZ(almost 1 GHz).
IF is about 300MHz。
The mixer needs high IIP3, and low NF.
The mixer need 50 Ohm input and output match. This is the biggest problem.
How can i select mixer? Is Gilbert OK?
If the transconductor of the gilbert is common source, it has good NF and IIP3(use soucre degeneration) . But match to 50 OHm is difficult during such wide band
If i use common gate transconducto, NF is poor.
If i use resistive mixer, IIP3 is good. However, NF is poor and CG is negative.
Anybody can introduce a good structure?
Thank you very much~~~
The input signal is wideband from tens of MHz to tens of hundreds of MHZ(almost 1 GHz).
IF is about 300MHz。
The mixer needs high IIP3, and low NF.
The mixer need 50 Ohm input and output match. This is the biggest problem.
How can i select mixer? Is Gilbert OK?
If the transconductor of the gilbert is common source, it has good NF and IIP3(use soucre degeneration) . But match to 50 OHm is difficult during such wide band
If i use common gate transconducto, NF is poor.
If i use resistive mixer, IIP3 is good. However, NF is poor and CG is negative.
Anybody can introduce a good structure?
Thank you very much~~~