Jitter Man
Community Member
Offline
Am I? Or am I so sane that u just blew your mind?
Posts: 50
|
Junkwar, Rather than using PSS as your base analysis, use QPSS. It will allow you to place your output frequency as close to zero as you like without penalty.
Having said this, I would like to suggest a possible solution that is even more efficient. Say you were able to perform the analysis using PSS with a 1MHz output frequency. Then consider what would happen to the result if you changed the output frequency to 100KHz. If the circuit bandwidth is much greater than 1MHz, the results should not change much. Now consider shifting the frequency to 10KHz, 1KHz, 100Hz, 10Hz, 1Hz. The results for all of them should be the same, right? Here is where it gets interesting. Why not take it down to 0Hz? In concept this works, but if you tried this on the lab bench you would not be able to resolve the distortion product at DC from the other signals present at DC (offsets, biases, etc.). But when simulating with Spectre using the procedure outlined in the paper, you get the distortion product out separately from the other DC components. So, while I have not tried it, I believe you could use a 2.8GHz PSS analysis with the large RF at 5.6GHz, the small RF at 5.6GHz, and the LO at 2.8GHz. The output intermodulation distortion would be in the -2 sideband. This approach would be very fast as it would be the same cost as a single-tone PSS+PAC analysis.
|