Patent ID: 6218863
Filing Date: 2001-04-17
Classification: H03K

Abstract:
An input/output (I/O) circuit compatible with either a first type of logic signals or a second type of logic signals comprising:a connection node;a differential sense amplifier having one input coupled to the connection node and the other input coupled to a reference voltage;a pull-up circuit that includes at least one p-type field-effect transistor coupled between a positive supply potential and the connection node;a pull-down circuit that includes at least one n-type field-effect transistor coupled between the connection node and a negative supply potential or ground;logic circuitry coupled to the gate of the at least one p-type field-effect transistor of the pull-up circuit and the gate of the at least one n-type field-effect transistor of the pull-down circuit, the logic circuitry controlling the conductivity of the field-effect transistors responsive to an input signal and a mode signal such that a first representation of the input signal compatible with the first type of logic signals is provided at the connection node when the mode signal is in a first state, and a second representation of the input signal compatible with the second type of logic signals is provided at the connection node when the mode signal is in a second state, andwherein the logic circuitry comprises a pair of transmission gates having a common output node coupled to the at least one p-type field-effect transistors, the pair of transmission gates being configured to respectively couple either the input signal, or a high potential, to the common output node responsive to the first or second states of the mode signal.