Secondary precharge devices
March 13, 2024
- Dynamic gates are subject to problems with charge sharing.
- For example, consider the 2-input dynamic NAND gate in Figure (a). Suppose the output Y is precharged to VDD and inputs A and B are low.
- Also suppose that the intermediate node x had a low value from a previous cycle.
- During evaluation, input A rises, but input B remains low, so the output Y should remain high.
- However, charge is shared between CX and CY, shown in Figure (b). This behaves as a capacitive voltage divider and the voltages equalize at
