AMPLIFIER CIRCUIT, LC RESONANCE CIRCUIT, VOLTAGE CONTROL OSCILLATION CIRCUIT, PLL CIRCUIT, VIDEO SIGNAL PROCESSING CIRCUIT AND VIDEO TAPE RECORDER

摘要

PROBLEM TO BE SOLVED: To obtain a PLL circuit by which a stable synchronization signal is generated through the use of an LC resonance type VCO by providing the phase shift circuits of a phase in the oscillation output of an LC resonance circuit, feeding-back the signal to a voltage-current converting means and obtaining the oscillation output of a desired frequency. SOLUTION: In an LC resonance type VCO circuit 601 constituting the PLL circuit, an LC circuit 303 is connected to the output terminal of an amplifier circuit 304 and the output terminal of an oscillation reference bias power source circuit 301 to constitute an LC resonance circuit. The phase shift circuits 306 and 307 feed back a phase shift advance signal FORWARD and a phase delay signal DELAY to the amplifier circuit 304, they are added and amplified and the output signal AFCOSC of the LC resonance circuit is obtained. Differential control voltages VCP and VCM are generated from a control voltage VLPF in a level shift circuit 302 and a rate for adding and amplifying the phase advance signal FORWARD and the phase delay signal DELAY in the amplifier circuit 304 is variably controlled.