some issue for VCO phase noise simulation by cadence spectre

Dear all,

I have some issue for VCO phase noise simulation by cadence spectre.

I had simulated a 250MHz VCO phase noise.

But this simulation result seems not correct even change another VCO structure.

it is correct for VCO frequency be tuned 2.5G.

Does it something wrong?

it is simulation result for transient dft (250MHz)

it is simulation result for Phase Noise waveform

Obviously it is not correction.

it is PSS setting

VCO is stable after 30ns

and maxstep is set 100p

it is PNOISE setting

The result shall correct that VCO frequency be increased to 2.5G.

Does it something wrong for simulation setting?

Thanks for your help.

你是想说相噪奇差吗?那就把noise summary贴上来~

hi, thanks for your reply.
I will upload noise summary tomorrow.
Thanks.

it is VCO phase noise & noise summary.

The summary result seems ok but phase noise waveform seems some has some issue.

等会说中文了再回答这种问题

你的vco什么结构的?phase noise 怎么这么烂?

Beat Frequency 不该是2.5e9吗?

thanks

VCO phase noise simulation by cadence spectre