Retention flip-flop circuits for low power applications

Abstract

Two retention flip-flop topologies that utilize a data retention control circuit and a slave/retention latch (sub-circuit) to reliably retain a data bit during standby/sleep operating modes without the need for a local clock signal. The slave/retention latch is controlled using a local clock signal to store sequentially received data bit values during normal operating modes. During standby/sleep modes, the local clock signal is de-activated (i.e., by turning off the supply voltage provided to the local clock generator circuit), and the data retention control circuit operates in accordance with an externally supplied retention enable control signal to both isolate and control the slave/retention latch such that a last-received data bit value is reliably retained in the slave/retention latch. When normal operation is resumed, the local clock signal is re-activated, and the data retention control circuit controls the slave/retention latch to pass the last-received data bit value to an output driver.