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Open loop frequency response of a GRO or VCO (Read 1511 times)
polyam
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Open loop frequency response of a GRO or VCO
Jan 15th, 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
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deba
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Re: Open loop frequency response of a GRO or VCO
Reply #1 - Jan 16th, 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.
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polyam
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Re: Open loop frequency response of a GRO or VCO
Reply #2 - Jan 17th, 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




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