Forum › Category: Layout › How does dummy insertion impact flicker noise in PMOS current Mirrors?
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AvatarSemiconwiki Staff asked 2 weeks ago
Does Anyone know how dummy insertion impacts flicker noise in PMOS current Mirrors?, Please add your comments PMOS current Mirrors
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AvatarTechGuru answered 2 weeks ago
You can mitigate flicker noise by ensuring consistent current flow through the PMOS current mirror, and dummy transistors help achieve this by balancing process-induced variations. I also make sure that dummies do not introduce additional parasitic capacitance near the critical nodes, as this could degrade performance instead of improving it. Properly placed dummies lead to a more uniform electric field, which helps in reducing flicker noise over time.
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AvatarDigitalWorld answered 2 weeks ago
I always use dummy insertion in PMOS current mirrors to minimize stress-induced variations, which can directly impact flicker noise. Dummies help maintain uniform mechanical stress across the active devices, reducing threshold voltage mismatches that contribute to flicker noise. You should also ensure that dummies are placed symmetrically to avoid introducing new asymmetries in the layout.
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Avatarsemiconductor answered 2 weeks ago

We have observed that flicker noise increases when active devices are affected by edge effects. Dummies help by keeping the main transistors away from the process variations at the layout edges. This ensures that mobility fluctuations and oxide trap density variations are minimized, leading to better matching and lower flicker noise in PMOS current mirrors.