Charge sharing
March 13, 2024
- Charge sharing is serious when the output is lightly loaded (small CY ) and the internal capacitance is large.
- If the charge-sharing noise is small, the keeper will eventually restore the dynamic output to VDD.
- If the charge-sharing noise is large, the output may flip and turn off the keeper, leading to incorrect results.
- Charge sharing can be overcome by precharging some or all of the internal nodes with secondary precharge transistors.
- These transistors should be small, because they only charge the small internal capacitances and their diffusion capacitance slows the evaluation.
- It is sufficient to precharge every other node in a tall stack.
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| Charge-sharing noise |
