Input stage apparatus and method having a variable reference voltage

DETAILED DESCRIPTION The present invention is directed to an input stage and method having increased input signal noise margin for generating an output signal having a predetermined logic level in response to receiving an input signal having a voltage level.
The input stage includes an input buffer that includes an input to which the input signal is applied and an output at which the output signal is provided.
The input buffer also includes a reference terminal to which a reference voltage signal is applied.
The input buffer generates an output signal having a logic level based on the voltage of the input signal relative to the voltage of the reference voltage signal applied to the reference terminal.
The input stage further includes a voltage generator that generates a variable output voltage signal that is used as the reference voltage for the input buffer.
The voltage of the output voltage signal provided by the voltage generator is dependent on the logic value of the output signal of the input buffer.
In this manner, the reference voltage applied to the input buffer can be adjusted based on the logic level of the output signal in order to provide increased input signal noise margin.