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Antenna ratio and diodes
Antenna ratio and diodes
Physical Verification
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Antenna ratio and diodes. During etch, charge builds up on the conductor connected to a gate before an upper layer or a diode can drain it. The antenna ratio is the net's metal area divided by the gate-oxide area it drives; above the limit the charge can damage the gate. For each net, pick the minimal fix:
- OK - the ratio is already at or under the limit.
- Jump - route part of the net to a higher layer so less area accumulates on the offending layer. Preferred, because it is free. Valid when the jumped ratio falls under the limit.
- Diode - add a protection diode that drains the charge. It always works but costs area and adds leakage, so it is a last resort, used only when jumping cannot get the net under the limit.
Read each net's ratio (and its jumped ratio), then disposition it. Using a diode where a jump would do is marked wrong. Then Submit fixes.