Discrepancy between QSPICE and LTspice

QSPICE
1

I’m simulating the AC response of a passive LCR circuit using QSPICE and LTspice and the results look quite different (see attachments). Default convergence options were used in both cases.

The LTspice results look correct (they match what I expect theoretically). Additionally, they scale correctly along the frequency axes when the L and C values are scaled.

The QSPICE results don’t match the theory. Moreover, they don’t scale correctly when the L and C values are scaled, which is really baffling me.

Any suggestions would be appreciated.

Netlist and simulation results: Microsoft OneDrive

2

Rename this to .cir, and you can run it in Qspice. .option LFT=0 is added to force Rpar to infinite for all inductors. To precisely match LTspice, I’m not sure if adding Rser=1m to each inductor is necessary, as this depends on your LTspice settings in Hacks. But from the results, maybe just forcing Rpar to infinite is good enough.

galbraith_cochlea_sim (.option LFT=0).txt (2.9 KB)

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image1683×528 132 KB

LTspice and Qspice define inductor parasitics differently. Please refer to this post.
Filter Simulation don’t work - QSPICE - Qorvo Tech Forum

3

Thank you, that was indeed the issue.