The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Simulators >> RF Simulators >> Open loop frequency response of a GRO or VCO
https://designers-guide.org/forum/YaBB.pl?num=1484491922

Message started by polyam on Jan 15^th, 2017, 6:52am

Title: Open loop frequency response of a GRO or VCO
Post by polyam on Jan 15^th, 2017, 6:52am

Hello,

I have a 7 stage gated ring oscillator (GRO). I was wondering if anyone can help me to simulate the open loop frequency response (gain and phase) of a gated ring oscillator or similarly a ring oscillator. Theoretically, it is supposed to be like a continuous time integrator (1/s).

Thanks

Title: Re: Open loop frequency response of a GRO or VCO
Post by deba on Jan 16^th, 2017, 7:28am

I assume that the transfer function which you are talking is from the frequency control port(vctrl) to the output frequency. You can do a swept PSS analysis by varying vctrl, and plot the output frequency.

Title: Re: Open loop frequency response of a GRO or VCO
Post by polyam on Jan 17^th, 2017, 3:21am

Hi deba,

Thnks for the comment. But that's not what I am looking for. Let me be clearer. Please take a look at the figure I attached. It comes from this paper: "Design of a 5bit 1GSps VCO Quantizer for a CT Delta Sigma Modulator".
The blue profile shows the frequency behavior of the VCO (both gain and phase). It behaves like an integrator. You see. It has a low pass profile with a constant phase of -90 degree. This is what I am exactly looking for. Why? Because I want to estimate the delay of the VCO or GRO from the phase shift.

Let me see my problem from another view. I have a black box (VCO or GRO in my case). I want to see how much delay I have between input and output. I need to estimate this delay. One way was what I had asked before. Do you have any other solution for my problem?

Many thanks