define capacitive

Hi, all,

With the trend of integration, sometimes we do not need 50ohm ports block by block. For example, the LNA's output impedance and the mixer's input impedance do not have to match to 50ohm, if they can be ac coupled on-chip.

Therefore, here's my question: when the LNA's load is not 50ohm, but capacitive ( which varies with the sweeping frequency), how to define such a port in the RF simulators?

Thank you in advance.

L2F

In ADS , port component will accept complex impedances.

Put Z=R+(-) jX value in "Port Impedance" field.

If you would change your imaginary part of your impedance simply write a equation like...

Z=R+j*2*pi*freq*L or Z=R-j*(2*pi*freq*C)^-1

ADS accepts equations in component definition fields.

Spectre also accepts but depending on version.In 5.141 "port" component has a reactance field.