Patent ID: 6268750
Filing Date: 2001-07-31
Classification: H03H

Abstract:
A circuit for controllably varying the output impedance of an output driver circuit that is configured to drive a signal through a signal pad on a semiconductor device, comprising:a first FET array comprising a plurality of field effect transistors (FETs) electrically connected in parallel between a first voltage source and the signal pad, said first FET array comprising at least one of p-channel field effect transistor (PFET) and at least one of an n-channel field effect transistor (NFET), wherein at least one of said at least one p-channel field effect transistor (PFET) and at least one of said at least one n-channel field effect transistor (NFET) in said first FET array are enabled to conduct current when said signal pad is driven to a first voltage level, and wherein all of said plurality of FETs in said first FET array are disabled from conducting current when said signal pad is not driven to said first voltage level;wherein a predetermined combination of said remaining FETs in said first FET array are enabled to conduct current when said signal pad is driven to said first voltage level.