SENSE AMPLIFIER OPERABLE UNDER VARIABLE POWER SUPPLY VOLTAGE

Disclosed is a sense amplifier employing an emitter coupled logic (ECL) circuit. A constant voltage generating circuit independent of a change or a fluctuation of a power supply voltage level is provided. Two current-mirror circuits supply constant currents to the ECL circuit based on a generated constant voltage. Since a constant current independent of the change of power supply voltage level is supplied to the ECL circuit, the ECL circuit reliably converts a small potential difference generated between I/O lines into a current signal. Accordingly, no erroneous reading operation is performed.