Patent ID: 6335633
Filing Date: 2002-01-01
Classification: H03K

Abstract:
An input buffer interface within an integrated circuit coupled between a high supply voltage source and a low supply voltage source to accept one or more input signals, buffer said input signals, and to convert said input signals to output signals acceptable to internal circuitry within said integrated circuit, comprising:a) at least one input buffer circuit, whereby each input buffer circuit is comprising: an input terminal coupled to an input/output pad that is connected to external circuitry that will generate said input signal, a buffer output terminal coupled to said internal circuitry to transfer the output signal to said internal circuitry, a voltage adjustment terminal to receive a voltage adjustment signal indicating a buffer threshold trip point level that is an input voltage level of said input signal at which said output signal will change between a first output logic level and a second output logic level, an input amplifier connected between the input terminal and the output terminal to receive one of the input signals convert said input signal to the output signal, and a threshold trip point modification circuit connected between the output terminal and the voltage threshold adjustment terminal to modify the threshold trip point level as a function of the voltage adjustment signal; and b) a voltage adjustment means connected to said volatile adjustment terminal, comprising: an internal inverter constructed of a basic circuit connected such that the output of the basic inverter circuit is connected to the input of said basic inverter circuit to provide a threshold voltage level of said internal circuits, and a voltage adjuster connected to receive a stable reference voltage, connected to said internal inverter circuit to receive said threshold voltage level, and connected to the voltage adjustment terminal to provide said voltage adjustment as a function of the stable voltage reference and the threshold voltage of the internal circuits.