Tanner Custom IC Tools Create an .assert warning for dc operating point for transistor small-signal params in T-Spice

2023-02-10T08:26:40.000-0500
Tanner EDA

Summary

How to create a .assert warning for small-signal parameters when v(M1.vds)-v(M1.vdssat) > 300mv (T-SPICE)

Details

For specific transistors, you could use the expr part of .ASSERT.
If you want to do it for all MOSFETs, that will be more involved.
If you open the OpAmp design (TB_OpAmp_DC - TSP_DC) from the Shipping Files, then you can add the following to the additional SPICE commands:

.ASSERT N2margin_OP EXPR='XOPAMP.XN2.m1:vds-XOPAMP.XN2.m1:vdsat' MAX=300mv WHEN=OP
.ASSERT N2margin_DC EXPR='XOPAMP.XN2.m1:vds-XOPAMP.XN2.m1:vdsat' MAX=300mv WHEN=DC

One checks during OP and the other one checks during a DC Sweep and the following warnings will be given:

Warning : "TB_OpAmp_DC_TSP_DC.sp" line 72 Assertion N2margin_OP OP maximum: 300.0000m value: 392.3526m
Warning : "TB_OpAmp_DC_TSP_DC.sp" line 73 Assertion N2margin_DC DC@ 900.0000m left@ 888.6163m duration: 88.6163m maximum: 300.0000m value: 309.4120m
 

KB Article ID# KB000073616_EN_US

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