Differential comparator with an extended input range

摘要

A differential comparator is provided with an extended input range. In one embodiment, a differential amplifier is provided with a differential input buffer that allows for differential detection even with input voltage signal levels that extend two or more volts beyond the power supply voltage. A first transistor and a first resistor coupled in series are coupled in parallel with a second transistor and a second series resistor. The transistor drain terminals are both coupled to the power supply voltage, and a current source draws current from the common node of the resistors. Input voltages are supplied to the gates of the transistors, and the differential output voltages are provided from the transistor source terminals. A differential amplifier receives the differential output voltages and provides a single output voltage.