PROBLEM TO BE SOLVED: To implement a band extension of an emitter follower circuit.SOLUTION: The emitter follower circuit includes: a bipolar transistor Q1; an emitter resistor R4 or a constant current source of which one terminal is connected to an emitter of a bipolar transistor Q2 and the other terminal is grounded; a collector resistor R3 or a diode connection transistor of which one terminal is connected to a power supply potential and the other terminal is connected to a collector of the bipolar transistor Q2; and a capacitor C1 inserted between the collector of the bipolar transistor Q2 and a ground.
