Fix FET netlist multiplier calculation bug#49
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msaligane merged 1 commit intoReaLLMASIC:mainfrom Sep 9, 2025
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- Remove incorrect division by 2 in fet_netlist function - mult parameter now correctly represents fingers * multipliers - Fixes LVS verification failures for single finger transistors - Resolves automated netlist generation issues in upper-level designs Fixes issue where width=3,fingers=1 would generate mult=0.5 instead of mult=1
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@Subhampal9 @Landflier, can you please review? |
LuighiV
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Sep 7, 2025
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This file is not needed as part of the PR. Description in the github site for the PR is enough.
The only change required is in the actual source code file.
LuighiV
reviewed
Sep 7, 2025
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I've checked that this is an actual mistake. Thanks for noticing and submitting a PR.
msaligane
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Sep 9, 2025
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Problem
The fet_netlist function in src/glayout/primitives/fet.py contains an incorrect calculation for the transistor multiplier parameter that causes LVS verification failures and incorrect SPICE netlist generation.
Root Cause
Line 109 in fet_netlist function incorrectly divides the multiplier by 2:
Where
mtop = fingers * multipliersImpact
Solution
Remove the erroneous division by 2:
Verification
Test cases demonstrate the fix:
Files Modified
src/glayout/primitives/fet.py: Core multiplier calculation fixFET_MULTIPLIER_FIX.md: Technical documentation of the issue and resolutionThis change ensures correct SPICE netlist generation and resolves LVS verification failures in automated design flows.