Apparatus and method for level-shifting input receiver circuit from high external voltage to low internal supply voltage

摘要

A circuit and method for level-shifting an input signal are disclosed that provide for level-shifting of a the input signal where an external voltage level is greater than an internal voltage of the signal. In the present invention, the input signal is compared to a reference signal to produce a differential current signal reflecting the logic level of the input signal. The differential current signal is reflected through a pair of current mirrors operating from the external voltage level to drive a pair of resistive loads. Each of the resistive loads is coupled in series with a current sink between the internal supply voltage and a ground voltage. As a result, the input signal may be received and level-shifted with gain even when the internal supply voltage is less than twice a transistor threshold voltage without introducing significant distortion to the received signal.