Fujitsu Corporation

Motohiro Seto

Eiji Sugiyama

Hiroyuki Tsunoi

Yasunori Kanai

Naoyuki Ando

A latch circuit has two complementary hold loops therein for improving noise tolerance. The latch circuit includes a first gate for receiving a data and a first clock signal and outputting a first signal in response to a change in the clock signal. A second gate receives a second clock signal having an inverted polarity to that of the first clock signal. A third gate is operatively connected to output terminals of the first and second gates and outputs a first latch output. The latch circuit also includes a first hold line which supplies the first latch output to the second gate and a second hold line which supplies a second latch output of the latch circuit having an inverted polarity to that of the first latch output to the second gate. The second gate may have an inverted input terminal receiving the second latch output.

Latch circuit having two hold loops

In a master-slave type flip-flop circuit including a normal function in a normal mode for flip/flop operation and a scanning function in a scanning mode for testing an integrated circuit, the master-slave type flip-flop circuit comprises: a master stage having a first pair of differential transistors for taking in data, a second pair of differential transistors for latching data taken in to the first pair of differential transistors, a third pair of differential transistors for taking in scanning data, and a fourth pair of differential transistors for activating the second and third pair of differential transistors in the scanning mode; and a slave stage having a first pair of differential transistors for taking in data from the master stage, a second pair of differential transistors for latching data taken in to the first pair of differential transistors, a third pair of differential transistors for latching scanning data, and a fourth pair of differential transistors for activating the first and third pair of differential transistors in the scanning mode.

Growing community of inventors

Yokohama, Japan

Motohiro Seto