Abstract: A data storage circuit for receiving and holding a data value includes an input stage configured to receive a data value in response to the precharge phase changing to an evaluation phase and to hold the data value during the evaluation phase. An output stage has an output latching element for holding the value, two switching devices for updating the output latching element and an output. The switching devices each being controlled by respective signals from dual data lines, wherein, in response to the data value held in the input stage being a logical one, the first switching device updates the output latching element with a value indicative of the logical one and in response to the data value held in the input stage being a logical zero, the second switching device updates the output latching element with a value indicative of the logical zero.

Abstract: A master-slave flip-flop circuit is provided with a retention capability to support operation in both a normal mode and a retention mode. During the retention mode the retention circuitry drives the output signal via either a first path 16 or a second path 22, 24, 4, 10 in dependence upon the phase of the clock signal. During both phases of the clock signal the output signal is driven in a well defined state to reflect the signal stored within the retention circuitry. There is thus provided a clock independent retention master-slave flip-flop circuit. Both high density and high speed variants of the flip-flop circuit may use the technique.

Abstract: A master-slave flip-flop circuit comprises a master stage for retaining a master signal, a slave stage for retaining a slave signal and a retention stage. During a normal mode of operation, the retention stage captures a retention signal having a value dependent upon the slave signal. During a retention mode of operation, the retention stage isolates the retention signal from changes in the stage signal and retains the retention signal. During the retention mode the retention stage also provides a master restore signal to the master stage and provides a slave restore signal to the slave stage. The master restore signal and the slave restore signal have values dependent on the retention signal for configuring the master stage and slave stage such that the master and slave signals have values corresponding to the retention signal.

Abstract: A data storage circuit for receiving and holding a data value includes an input stage configured to receive a data value in response to the precharge phase changing to an evaluation phase and to hold the data value during the evaluation phase. An output stage has an output latching element for holding the value, two switching devices for updating the output latching element and an output. The switching devices each being controlled by respective signals from dual data lines, wherein, in response to the data value held in the input stage being a logical one, the first switching device updates the output latching element with a value indicative of the logical one and in response to the data value held in the input stage being a logical zero, the second switching device updates the output latching element with a value indicative of the logical zero.

Abstract: A master-slave flip-flop circuit is provided with a retention capability to support operation in both a normal mode and a retention mode. During the retention mode the retention circuitry drives the output signal via either a first path 16 or a second path 22, 24, 4, 10 in dependence upon the phase of the clock signal. During both phases of the clock signal the output signal is driven in a well defined state to reflect the signal stored within the retention circuitry. There is thus provided a clock independent retention master-slave flip-flop circuit. Both high density and high speed variants of the flip-flop circuit may use the technique.

Abstract: A master-slave flip-flop circuit comprises a master stage for retaining a master signal, a slave stage for retaining a slave signal and a retention stage. During a normal mode of operation, the retention stage captures a retention signal having a value dependent upon the slave signal. During a retention mode of operation, the retention stage isolates the retention signal from changes in the stage signal and retains the retention signal. During the retention mode the retention stage also provides a master restore signal to the master stage and provides a slave restore signal to the slave stage. The master restore signal and the slave restore signal have values dependent on the retention signal for configuring the master stage and slave stage such that the master and slave signals have values corresponding to the retention signal.