Push-pull cascode logic

A cascode logic circuit provides a pair of differential output nodes (12,13) that are pulled up by a pair of cross-coupled P-channel output transistors (11,14). The output nodes (12,13) are connected to outputs of an N-channel combinatorial network (20) that receives a differential input and functions to connect one of the output nodes (12,13) to a positive supply (Vdd) and the other to ground (Vss), depending upon the differential input, thus providing a push-pull effect. The output nodes (12,13) may be connected to the differential output of the combinatorial network (20) by source-drain paths of separate N-channel transistors (17,18), with the gates of these transistors connected to the positive supply (Vdd) to capacitively isolate the output nodes (12,13) from the combinatorial network (20); alternatively, the gates of these transistors may be clocked. A fully static latch is provided by adding cross-coupled N-channel transistors connecting the output nodes to ground, so the low side of the output is held down instead of being allowed to float. The channel types of the transistors may be reversed in another embodiment; the pull-down transistors of the differential amplifier may be N-channel and the logic and latching transistors P-channel.