VOLTAGE CONTROLLED OSCILLATOR HAVING FUNCTION OF AUTO AMPLITUDE CONTROL

摘要

A voltage controlled oscillator having an automatic amplitude control function is provided to reduce a phase noise and a voltage consumption by not using a current source' '. In a voltage controlled oscillator having a function of an automatic amplitude control, a voltage controlled oscillator(10) and an auto amplitude controller(20) are installed. In the voltage controlled oscillator(10), a resonance circuit(11) generates a resonance signal. A differential amplifying circuit generates and outputs two oscillation signals. An active load controls a gain of the oscillation signal. In the auto amplitude controller(20), a peak detector(21) detects and rectifies each peak. A low pass filter(22) transforms a rectified signal into a direct voltage and outputs the direct voltage. And, a comparator(24) outputs a control voltage to control a resistance of the active load.