Sorry for the delay in responding. Thanks for the additional
On 15/09/16 1:57 AM, al davis wrote:
There is another hidden issue here, something I have been working on.
As originally stated, rise=fall=delay=0, there is nothing in the
circuit to hint at what time stepping to start with, so the automated
step control would miss the oscillation. In the original, the
requested step of 1ps was a hint, but otherwise with what Felix
suggested, it would have skipped by the oscillation. You might call
this a "bug" but most other simulators are worse. By giving a finite
rise time, the simulator now has some basis to figure out time
stepping and can go from there. You just need something, somewhere,
that somehow requests a step size less then the expected period of the
ngspice behaves differently with the statement VCC 10 0 PULSE(0 8), it
uses the step time by default when not explicitly specified.
1ps is a very small time step for a 100MHz oscillator. I am injecting a
current pulse into the oscillator and measuring the phase shift in the
signal. I need to measure down to 0.01 radians. I was experimenting with
ngspice with different step times but the phase shifts I was observing
were not sensible.
Now I have a better understanding on how to use GNUCap I can repeat the
experiments using it.
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