Voltage controlled oscillator with frequency stabilized and PLL circuit using the same

摘要

A voltage controlled oscillator includes N (N is an integer equal to or more than 2) inversion-type differential amplifiers and a level converter. The N (N is an integer equal to or more than 2) inversion-type differential amplifiers are connected in a loop such that each of output signals outputted from one of the N inversion-type differential amplifiers has an opposite polarity to a corresponding one of output signals outputted from the next one of the N inversion-type differential amplifiers. The level converter is connected to one of the N inversion-type differential amplifiers as a last inversion-type differential amplifier to generate an oscillation signal from the output signals outputted from the last inversion-type differential amplifier. Each of the N inversion-type differential amplifiers operates in response to a predetermined voltage and a control voltage.