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Regarding Smoothness in transient analysis

RFStuff

 Dear All,

I created a verilogA module.

What it basically does is as below:-

It is a simple sine wave generator. 

I stored the sine wave  time & amplitude in a text file for one period of the sine wave.

The verilog A code reads the file and generates the sine wave for the entire transient simulation time.

But the problem is:-

If I am not using the strobeperiod, the curve is NOT smooth at all.

But when I use stobeperiod=1ps then it becomes smooth.

I was thinking that the  transient simulation will be evaluated at each time point stored in the file.

Can anybody please tell why this is happening.

Kind Regards,

Parents

  • Hi RFStuff,

    The simulator will only place timesteps that are sufficient to resolve the equations, not necessarily enough that the sine wave looks like a sine wave.  One way to help the simulator take more timesteps is to use the bound_step() function - this should be a little nicer to the simulator (than strobeperiod) as it still has flexibility on the time points, but now they are limited to a maximum time between steps. Work out how many samples/points you wantper cycle and work out the max timestep from there.

    I hope that this helps.

    Regards,

    Lawrence.

Reply

  • Hi RFStuff,

    The simulator will only place timesteps that are sufficient to resolve the equations, not necessarily enough that the sine wave looks like a sine wave.  One way to help the simulator take more timesteps is to use the bound_step() function - this should be a little nicer to the simulator (than strobeperiod) as it still has flexibility on the time points, but now they are limited to a maximum time between steps. Work out how many samples/points you wantper cycle and work out the max timestep from there.

    I hope that this helps.

    Regards,

    Lawrence.

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