C
cubeagree
- Jan 1, 1970
- 0
Hello,
I am trying to design a 24GHz transistor oscillator (feedback with
transmission line resonator). I have only s-parameter files from the
transistor available - so I can do only linear analysis to evaluate
whether the oscillator will be unstable. I am using ADS for simulation
- with the modul "osctest" it is possible to evaluate the closed loop
gain. According to Nyquist criterium the loop gain should be greater
than 1 when the phase is zero.
All the examples I have seen are using real transistor models , i.e.
they are starting with the linear analysis and afterwards a harmonic
balance simulation to confirm the oscillation.
My loop gain is only "a little bit" greater than 1, actually 1.006 ! I
have tried to change feedback characteristics and I have taken other
transitor s-parameter, but the result is the same = only 1.006 of loop
gain.
What are your experience with the loop gain when using only s-
parameters ? Does it make sense to build this oscillator on the basis
of this simulation ?
Thanks for your feedback !
Regards
Peter
I am trying to design a 24GHz transistor oscillator (feedback with
transmission line resonator). I have only s-parameter files from the
transistor available - so I can do only linear analysis to evaluate
whether the oscillator will be unstable. I am using ADS for simulation
- with the modul "osctest" it is possible to evaluate the closed loop
gain. According to Nyquist criterium the loop gain should be greater
than 1 when the phase is zero.
All the examples I have seen are using real transistor models , i.e.
they are starting with the linear analysis and afterwards a harmonic
balance simulation to confirm the oscillation.
My loop gain is only "a little bit" greater than 1, actually 1.006 ! I
have tried to change feedback characteristics and I have taken other
transitor s-parameter, but the result is the same = only 1.006 of loop
gain.
What are your experience with the loop gain when using only s-
parameters ? Does it make sense to build this oscillator on the basis
of this simulation ?
Thanks for your feedback !
Regards
Peter