Exclusive OR Circuit with Diodes Arranged to Permit Operation with Low Voltage Input Circuits
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-09
In an Exclusive OR circuit of the type in which two input signals are are each applied oppositely to the base terminal of one transistor and the emitter terminal of a second transistor, the connection from each input terminal to the associated base terminal includes a diode that is poled in the direction to oppose conduction of the signal current. A resistor supplies current to the base terminal when the diode is turned off by an up-level signal at the associated input terminal. When an up-level signal is applied to one terminal and a down-level signal is applied to the other input terminal (the Exclusive OR condition), this circuit arrangement prevents the down-level signal at one input terminal from loading down the circuit that is applying an up-level signal to the other terminal.