Patent US 4,136,292

A voltage sensing circuit of differential input type includes at least one differential amplifier circuit connected between two complementary data lines of a semiconductor memory. The differential amplifier circuit detects data in response to a minute potential difference between the data lines and amplifies the same by a substantial change in conductance g.sub.m of metal oxide semiconductor field effect transistors (MOSFET) used in the circuit. When data is read from a semiconductor memory onto the data lines, the differential amplifier sensing circuit detects the data quickly by detecting potential changes of the data lines.