rfmagic
|
Hi,
I am trying to figure out how the circuit simulators (ADS or Cadence and so forth..) actually measure the S-parameters of a 2-port network. The classical definition of S-parameters is to use the incident (Vi) and reflected (Vr) voltage waves. For example in order to measure S11 we will calculate S11=Vr/Vi. This is actually the way a network analyzer works. It drives the port with an incident wave and using a directional coupler it separates the reflected wave and thus can measure it.
What I find hard to understand is, suppose that my 2-port network includes a series resistor and a shunt capacitor (both lumped) with 50 ohm ports.How does the simulator measure the reflected wave (Vr). there is no directional coupler used...
Is it possible to reproduce the S-parameters simulation results using an AC simulation?
Thanks in advance....
|