I want to plot the I/O characteristics of PFD to see the dead zone. I got to know from the previous post that I have to plot the current and sweep variable, but can anyone please elaborate the process on how to sweep the variable.
I want to sweep the phase of Fref and Fdiv .... I have done dc analysis in cadence virtuoso ADE enviroment..... I am not sure which parameter to sweep and how to sweep. Is it AC phase or delay time? I have attached the picture below.. Please have a look.
I want to plot the I/O characteristics of PFD to see the dead zone. I got to know from the previous post that I have to plot the current and sweep variable, but can anyone please elaborate the process on how to sweep the variable.
Connect a capacitor to your charge pump output. Make sure its large enough so that when the CP turn on, the voltage does not change too much.
Start with two vpulse sources that have a phase offset between them as a parameter. Run a transient simulation and see how much charge is dumped into your capacitor (the difference in voltage before up or down went became high and voltage after both of them became low multiplied by the capacitance). And then you do a parametric sweep on the offset.
Ideally, for a 20ps phase offset, the amount of charge dumped will be 2x charge dumped for a 10ps offset.
By the way, I really don't see the point in measuring deadzone like this. The thing you need to ensure is that for your minimum reset pulse width, both the current sources turn on and settle to their final DC values in the slowest corner.
Use the delay function to plot the delay between the two wave-forms and then do a Y vs Y plot.
Alternatively you can save both your voltage/current/charge waveform and your delay waveform in csv files and plot them in Matlab/Python/Julia etc