RF BUFFER CIRCUIT AND OPERATING METHOD

摘要

PROBLEM TO BE SOLVED: To provide an RF buffer whose power level is kept constant even when a power level of an input signal is changed. SOLUTION: The RF buffer provides the output of a single termination output signal and a differential output signal. An amplifier 40 compares a mean voltage of the differential output signal with a reference voltage VR. The amplifier 40 supplies a bias current flowing to a 1st transistor(TR) 24 and a feedback signal to control a bias current flowing to a 2nd TR 46 and that is a mirror current. The bias currents are used to generate differential output signals OUT-, OUT+ substantially independently of a signal level at an input terminal 20. The signal current flowing to the 1st TR 24 controls an output TR 66. The signal current flowing to a 2nd TR 46 controls other output TR 56 in a push-pull output stage of an RF buffer 10.