Questions about differential LNA design in HSpice

Hi everyone,

i wish to design a differential LNA that center at 2.4GHz. the input impedence is match to 50ohm. i'm using hspice for my simulation. I have several questions want to ask:

1. to simulate the s-parameter, zin and zout using hspice, i need to specify a output node voltage and a input ac voltage source. but since differential amp has vin+,vin-,vout+ and vout-, how can i specify its input voltage and output voltage node?

2. For single end LNA noise analysis, normally we will use .noise v(vout) vin to simulate. But how can i simulate the noise of the differential amp? (since diff amp have vin+,vin-,vout+ and vout-)

Thanks for your helps...

Hi

You can use ideal transformer (1:1) to have single input and single output nodes.
Then noise figure calculations will be the same like single ended LNA.

Regards

Hi Grig,

Can you please tell me in the details how to connect the transformer to the input port and output port?

Thanks.