How to use the OSCport in OSC design?

oscport

Should OSCport be placed in anywhere in osc design? Or should be placed in a particular place?
I don't know what it used for?

oscport in ads

you can get all from the ads help document!

I could not understand the help from OSCport property,It's only to say how to set it ,but not said where I can put it? could you help me?
Thank you

OscPort

The ADS OscPort model for HB analysis is based on the Nyquist stability test critetion, which is described in "Microwave Transistor Amplifiers, Analysis and Design, 2nd Ed, G. Gonzalez", chapter 5, section 2. The idea is measuring the close-loop gain and phase to determine the oscillating condition and frequency.

The following is my opinion about OscPort usage, please comment

For a low frequency osc, the feedback path is clear. The Oscport should be inserted in the circuit in the feedback path pointed in the direction of the oscillator's gain. For example, in a common emitter/source osc circuit, the OscPort should be put in series with the base/gate of the transistor and pointing toward the transistor.

For a microwave osc, the feedback might be achieved by parasitic parameters of the transistors. The osc could be treated as a two port negative resistance model (see Gonzalez book ch5.3). The OscPort should be put between the transistor and the resonant network. Its direction does not really matter, based on my experiment, there is no difference in simulation results and time.