Periodic AC Analysis

I am simulating the same circuit and getting its IP3 characteristic. This time Periodic AC analysis (PAC) and Periodic Steady State analysis (PSS) have been utilized.

Unlike in QPSS (quasi-periodic steady state) analysis, one tone is used. It means that one frequency will be applied in the input signal, e.g. 98MHz. Thus the positive (+) and the negative (-) inputs will have the same frequency and magnitude but the other input will have 180 degrees phase shift.

Source type is sine wave (voltage source) and the small signal parameter is employed to input the value for the PAC magnitude and PAC phase as well.

PSS analysis set-up:
1. The name of the frequency F1 with a value of let's say 98MHz is a large signal.
2. Ticking the auto calculate will give you a beat frequency of 98MHz.
3. For the output harmonics, you can select from range, let's say from 1MHz to 1GHz; and make 10 orders perhaps.
4. Select the desired signal frequency (98MHz).
5. For accuracy, tick conservative.
6. The input signal should be variable so you can sweep a range, maybe from 60dBuV to 120dBuV.
7. For the sweep type, I usually use the linear type with step size of 5.
8. Furthermore, the integration method parameter should be gear2only. This is optimized in the PSS Options section.

PAC analysis set-up:
1. Since 98MHz is used in the PSS analysis, then the Beat frequency is 98MHz.
2. Sweep is Absolute.
3. Single Point frequency is 100MHz.
4. For the sidebands, you can select from range, from 1MHz to 1GHz perhaps.
5. Select index frequency and some order frequencies like 96MHz and 100MHz.