Register with current-steering input network

Abstract

A regenerative amplifier is coupled to a combinational current-steering network to provide a combinational logic and register combination. A differential change in current on the register's input nodes due to current steering is amplified to provide complementary logic values at the output nodes of the register responsive to a clock signal. Various combinational logic functions are implemented by current steering networks. Such a configuration provides the advantages of economy of size, cost and power consumption in the combinational layout because the current steering transistors may be made smaller. Furthermore, such a configuration provides the advantage of decreased set-up time in a registered data path and immunity from external sources of noise via common mode rejection. In one embodiment, a regenerative amplifier includes cross-coupled inverters. Current steering circuits steer current between regenerative amplifier input nodes depending on the output value of the logical function implemented by the combinational network.