impedance is calculated wrong : cadence virtuoso

[mohamis288]

I have created a circuit. now I want to calculate input impedance at 1GHz frequency. But I think result is apparently wrong. for example, real part is in the order of 100k ohms, while real part in simulation has been obtained equal to 168 ohms. what is my fault?

 

[Dominik Przyborowski]

Try to calculate input impedance. Use only your input cap, biasing resistor and gate cap shunting this resistor.