Logic output control circuit for a latch

Abstract

A logic output control circuit for selecting between stored and nonstored outputs from a data input and a clock having a data pass gate MOS transistor receiving a logic signal at its data input and either blocking the signal or passing it to a cross-coupled inverter gate latch depending on a control signal at its control gate terminal. The control signal is derived in one embodiment by a logic gate with a programming signal input, a clock input and a control signal output, and in a second embodiment by a set of pass gate transistors respectively receiving a clock signal and a fixed level signal and controlled by a programming signal. When the programming signal has one logic level, the data pass transistor is always on and the logic signal flows continually to the output. When the programming signal has the other logic level, the data pass transistor switches on and off with the clock signal and the circuit operates as a latch. The clock signal may be an input clock or a pulsed clock which is an edge triggered version of the pin clock signal.