How to reduce reference spur in injection locked PLL?
时间：04-05
整理：3721RD
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Hello everyone,
I'm having trouble reducing the spur in my subharmoniclly injection-locked ring oscillator. From literature I understood that reference spur can be reduced by ensuring that,
F_ro = N*F_inj, where N is the frequency multiplication factor.
I set up a ring oscillator in cadence and manually inject a pulse into it. I made my best tuning the natural frequency of the RO to be exactly N times F_inj. However in PSS report I still see -22 dB spur.
I see many recent subharmonic injection-locked PLL publications have achieved spur performance way better than my manually-tuned oscillator.
What is the reason of this and how can I reduce it?
Sincerely expect your help
Lucas
I'm having trouble reducing the spur in my subharmoniclly injection-locked ring oscillator. From literature I understood that reference spur can be reduced by ensuring that,
F_ro = N*F_inj, where N is the frequency multiplication factor.
I set up a ring oscillator in cadence and manually inject a pulse into it. I made my best tuning the natural frequency of the RO to be exactly N times F_inj. However in PSS report I still see -22 dB spur.
I see many recent subharmonic injection-locked PLL publications have achieved spur performance way better than my manually-tuned oscillator.
What is the reason of this and how can I reduce it?
Sincerely expect your help
Lucas
an injection locked ring oscillator is NOT A PLL! so lets start there.
how are u injecting the subharmonic? How are you removing the oscillating power? what are you doing to make the ring oscillator ONLY free run at the output frequency?