Hybrid data and clock precharging techniques in domino logic circuits minimizes charge sharing during evaluation

摘要

A domino logic circuit (400) includes a precharge device (101) precharging a precharge node (110) during a precharge phase and a logic block (121, 123, 125, 127, 129) receiving plural input signals (A, B, C, D, E) to conditionally discharge the precharge node. In this improvement a second precharge device (155) precharges an intermediate node (122) when a particular input signal (E) controls its corresponding logic device to be nonconducting. The intermediate node precharged by this second precharge device may be any intermediate node including the last in a serial chain from the precharge node. This second precharge device may be used with a third precharge device (114) according to the prior art which precharges the intermediate node during the precharge phase. This domino logic circuit may be used with another precharge device (150) controlled by a second input signal (D) different from the first input signal. This additional precharge device may be used to precharge the same intermediate node or another intermediate node. If the input signal controlling the second precharge device is unconstrained, then the circuit preferably includes a clock controlled precharge device to precharge the intermediate node during the precharge phase and a discharge control device disposed between said logic block and ground preventing discharge during the precharge phase. Alternatively, the input signal may be clocked and guaranteed low during the precharge phase. In this case, the clocked precharge of the intermediate node and the discharge control device are optional. <IMAGE>