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| COMB CAPACITOR PYCELL |
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PyCell Description:
| This PyCell creates a comb capacitor on the user's choice of metal1 through metal7. This capacitor exploits lateral capacitance, which is precisely controlled by photolithography, rather than vertical capacitance, which is less precisely controlled by planarization. Optional parameters allow users to include dummy fingers to improve matching, and to designate the bottom metal layer as a shield layer beneath all fingers. The shape edges are aligned on all active layers for precise matching, based on the minimum spacing of the layers selected by the user. The connectivity, spacing and contacts conform to the design rules for the process in use. |
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| PyCell Plot: |
The capacitor layout below shows a comb capacitor constructed using metal layers 2-6, with a bottom shield on metal1 and optional dummies.
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The layout below shows the same capacitor as above, with only the metal1, via1 and metal2 layers visible. Notice that the vias connect only one terminal to the bottom shield, maximizing shielding without shorts.
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Parameters for the PyCell Layout Shown Above:  |
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Results of Different Parameter Values:
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The two capacitor layouts below are plotted to the same scale. The left plot uses metal 5-6, while the right plot uses metal 5-7. Please note that the PyCell automatically took into account the different metal and via spacing rules required for metal 7, and spaced the rest of the capacitor layout accordingly.
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| Comb capacitor on Metal 5-6: |
Comb capacitor on Metal 5-7: |
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Process Technology:
| The PyCell layouts above were generated for a generic 130nm process. This same PyCell source code has been tested to create design rule correct layout for both minimum spacing rules and recommended rules for foundry 65nm and 90nm processes, and for minimum spacing rules at 130nm, 180nm and 250nm. |
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Source Code:
| PyCell name: |
CombCapacitor |
| Source name: |
combCapacitor.py |
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