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Design >> RF Design >> Diff LNA Ext vs. Sch simulated Power difference
https://designers-guide.org/forum/YaBB.pl?num=1185987166

Message started by eng on Aug 1^st, 2007, 9:52am

Title: Diff LNA Ext vs. Sch simulated Power difference
Post by eng on Aug 1^st, 2007, 9:52am

Hi, I designed a classical Diff LNA at 400 MHz the current consumption was ~ 800u in schematic sim. however in post layout simulation the circuit draws ~500u from vdd. LVS was clean.

Can anybody comment on what might be the problem which causes that much current difference? How can I debug the extracted view to see the voltages and dc operating parameters on the individual components of the circuit?

Thanks
eng

Title: Re: Diff LNA Ext vs. Sch simulated Power differenc
Post by didac on Aug 3^rd, 2007, 12:39am

Hi eng,
You have a strange situation here, I usually expect an increase of power consumption after the layout not a decrease for the same circuit specs. Have you verified with your documentation the switches for the extracted view? For debugging you can run the dc analysis and enter the extracted view and directly using the ADE command annotate DC Voltages or DC operating points will print the data over the extracted, another possibility is to directly select the nodes that you want with Outputs to be saved but usually first you must do in the LSW palette Edit-->Set Valid Layers-->All Valid before you can save an extracted node.
You can start trying different extractions and see how current varies(i.e. first C only, R only,RC...).
Hope it helps,