Patent ID: 6118316
Filing Date: 2000-09-12
Classification: H03L,H04L

Abstract:
A semiconductor integrated circuit generating a stabilized oscillation signal based on an input signal, the circuit comprising:a plurality of unit circuits connected in series, each of said unit circuits having at least an oscillator to output an oscillation output signal, a divider, and a phase comparator which form at least one part of a phase-locked loop; each of said unit circuits being connected such that a frequency of the oscillation output signal of one of said unit circuits is higher than a frequency of the oscillation output signal from a unit circuit directly preceding the one of said unit circuits,the oscillation output signal of the one of said unit circuits being said stabilized oscillation signal, wherein;each of said unit circuits further comprises a loop filter, the loop filter of the one of the unit circuits having a time constant smaller than that of the loop filter of the directly preceding one of the unit circuits, wherein the loop filter provided in the one of said unit circuits generates an oscillation-frequency control signal having a greater control range of a control voltage than an oscillation-frequency control signal generated from the loop filter in the unit circuit directly preceding the one of said unit circuits, andthe oscillator provided in the one of said unit circuits generates said oscillation output signal having a larger variation with respect to said control range of said control voltage than that of said oscillation output signal generated in the unit circuit directly preceding the one of said unit circuits.