Problem with input impedance of post layout LNA

[bcdeepak]

i designed an inductively degenerated LNA for single frequency...ckt simulation is fine..i drew its layout...DRC,LVS are fine..but post layout is too bad
the input impedance is only 2 ohm...instead of 50ohm...what should i do?? plz help me

deepak

 

[jecyhale]

Re: LNA post layout

The problem will be caused by the post layout modeling file.
And you'd better connect the foundry to verify.

 

[rillyxue]

Re: LNA post layout

please check the Q of the input match network. and check if the peak frequency is varify from the wanted frequency.

 

[aomeen]

Re: LNA post layout

Try to locate wither it's a Layout problem or parasitic modeling problem...

For example, run the extraction for the inductor alone, and check wither Q and L are equal to that given from schematic. repeat for other elements "RF transistor, Capacitors, etc."

It's possible also that you have double counted parasitics. "parasitics included in the RF models are re-extracted by the extraction tool..." I has similar experience with calibre once...

 

[bcdeepak]

Re: LNA post layout

hi
thanks for your reply

my output matching S22 is fine...but input matching S11 is too bad..is this the inductor problem???
i am using the inductors provided by UMC.