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# half harmonic frequency in PSS analysis

Last post Thu, Apr 30 2009 10:29 AM by Andrew Beckett. 1 replies.
 Started by Andy Liu 30 Apr 2009 08:34 AM. Topic has 1 replies and 1502 views
• #### Thu, Apr 30 2009 8:34 AM

• Andy Liu
• Joined on Thu, Apr 30 2009
• Posts 4
• Points 110
half harmonic frequency in PSS analysis
 I am designing an LC based voltage control oscillator. I want to simulate phase noise of my oscillator, but, I ALWAYS got a very bad phase noise performance (for example, -60 dBc/Hz @ 1 MHz offset, compared to my expectation -110 dBc/Hz). The reason is that in the periodic steady state analysis (PSS), the fundamental frequency is simulated wrong. I estimate the fundamental frequency is 5 GHz from the transient waveform, whilst the fundamental frequency given by PSS simulation is 2.5 GHz. Has anyone encountered or does anyone have any knowledge of this problem?I figure out a method to get around this half harmonic frequency problem. In the pnoise analysis, people usually choose “sweep type” as “relative”, and “relative harmonic” as 1. I wonder if I can choose “relative harmonic” as 2 to compensate the half harmonic in PSS simulation. Thank you.
• Post Points: 20
• #### Thu, Apr 30 2009 10:29 AM

Re: half harmonic frequency in PSS analysis
 I answered the same question over on the RF forum.Andrew.
• Post Points: 5