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Simulators >> Circuit Simulators >> PSS frequency domain results
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Message started by Murphy.Dave on Jul 28^th, 2005, 2:30am

Title: PSS frequency domain results
Post by Murphy.Dave on Jul 28^th, 2005, 2:30am

Hello all,

I running PSS simulations for a number of LC oscillator varients (using Spectre through Ocean scripts). I have set it up so that I save all currents and voltages.

>>> saveOption('save "all" 'pwr "all" 'currents "all")

In the time domain (pss_td), the simulations produce results for all the node voltages and all the currents into all the devices. However in the frequency domain (pss_fd) the simulations only produce results for currents into inductors and voltage supplies.

Is there a way to generated frequency domain results for the currents into active devices (MOSFETS) and capacitors??

Any help is appreciated.

Dave

Title: Re: PSS frequency domain results
Post by Andrew Beckett on Jul 31^st, 2005, 9:27pm

You need to turn on the option "useprobes" (spectre -h options). In OCEAN:

Code:

option('useprobes "yes")

This tells spectre to put an iprobe in series with all devices, and measure the current through that. Spectre cannot normally measure frequency domain device currents (in ac simulations too) without using useprobes.

You should be cautious of using useprobes (and subcktprobelvl) for big circuits because it can add a large number of iprobe components (check the circuit inventory in the simulator output) which can lead to increased memory usage and slower simulations. Just be careful, that's all...
There are plans to solve (or at least minimise) this requirement for iprobe insertion in an upcoming release.

Best Regards,

Andrew.