JPS6416023A - Pll circuit - Google Patents

Abstract

PURPOSE:To obtain a phase comparison characteristic wide in linear range by superimposing a phase comparison characteristic depending on a fundamental wave onto a phase comparison characteristic depending on harmonics. CONSTITUTION:The titled PLL circuit consists of a signal generating circuit 1 generating an output signal having the same frequency and a frequency being an integral number of multiple of the frequency as the input signal Si, a frequency variable signal generating circuit 2 generating a signal of the same frequency as that of the input signal Si and a frequency signal being an integral number of multiple and whose frequency is to be controlled, a multiplier circuit 3 multiplying the output signal of the signal generating circuit 1 with the output signal of the circuit 2, and a loop filter 4 receiving the output of the multiplier circuit 3 and supplying the output to the circuit 2. In the multiplier circuit 3, at least the same frequency component as the input signal Si and the double frequency components are multiplied. Then the phase comparison characteristic as to the 2nd harmonics and the phase comparison characteristic of the fundamental wave are synthesized. Thus, the linear region is widened more than the phase comparison characteristic as to the fundamental wave only.