LNA + mixer simulation ?

[mitgrace]

Dear all :

I work on LNA+Mixer simulation of FM band. Now I have some question .

1.Does FM is wide band ? I match the input stage, I found the S11 in the smaith chat is very high range, so that the Gain in not flaten. Like 72M is 13dB 90M is 25dB, 108M is 17dB. How do I to solve the problem ?

2. LNA + mixer Gain simulation. I can simulate the LNA , Mixer Gain, standalone. But I casecad the LNA+Mixer , I check the Conversion Gan, It can't work ? What is the Gain , See the S21 or other method . Thanks

 

[khouly]

u need to make the S parameter simulation detect frequency translation
, and try to use HB simulation to get the gain

about the gain flatness , i think u should use wide band matching circuit and also try to make the mixer gain flat alone


khouly

 

[Youncen]

You should use simulation other than sp ,coz the frequency is to low,beside the input S11 is impossible well matched at this frequency.
maybe ac simulation is suitable

 

[mitgrace]

Dear All :

So that in the 72M ~ 108M , It is hard to matching for this band or there are still have good mwthod for matching , Thanks

 

[khouly]

u ca search for wide band matching techniques

khouly