OUTPUT BUFFER CIRCUIT HAVING SIGNAL FEED FORWARD FOR REDUCING SWITCHING-INDUCED NOISE

摘要

PURPOSE: To reduce the switching-induced noise of an output buffer circuit by forming the sink and source currents of the circuit in two-phase two-step currents. CONSTITUTION: A pull-down feedforward circuit 36 is connected between an input terminal VIN and an output pull-down transistor N3. The circuit 36 makes an intermediate circuit element start a relatively small sink current through the transistor N3 in response to a fist signal inputted to the input terminal VIN before the circuit element starts a relatively large sink current through the transistor N3. A pull-up feedforward circuit 35 is connected between the input terminal VIN and an output pull-up transistor P3. The circuit 35 makes an intermediate circuit element starts a relatively small source current through the transistor P3 in response to a second signal inputted to the input terminal VIN before the circuit element starts a relatively large sink current through the transistor P3.