Patent ID: 8836398

Claim:
A flip-flop circuit comprising: a multiplexer configured to receive a first data bit, a scan data bit, a scan enable control signal and a binary logical compliment signal of the scan enable control signal, wherein the scan enable control signal and the binary logical compliment signal of the scan enable control signal determine whether a data output of the multiplexer is the binary compliment of the first data bit or the binary compliment of scan data bit; a master latch configured to receive the data output of the multiplexer, a clock signal, a binary logical compliment signal of the clock signal, a retain control signal and a binary logical compliment signal of the retain control signal, wherein the clock signal, the binary logical compliment signal of the clock signal, the retain control signal and the binary logical compliment signal of the retain control signal determine when the binary logical value of the data output of the multiplexer is presented on the output of the master latch and when the output of the master latch is latched in the mater latch; a transfer gate wherein the transfer gate transfers data from the output of the master latch to the output of the transfer gate when the clock signal transitions from a high logical value to a logical low value; a slave latch configured to receive the output of the transfer gate, a second data bit, the clock signal, the binary logical compliment signal of the clock signal, the retain control signal, the binary logical compliment signal of the retain control signal, a slave control signal and a binary logical compliment signal of the slave control signal wherein the clock signal, the binary logical compliment signal of the clock signal, the retain control signal, the binary logical compliment signal of the retain control signal, the slave control signal and the binary logical compliment signal of the slave control signal determine whether the output of the transfer gate or the second data bit (D 2 ) is latched in the slave latch.