JPH0328834U

JPH0328834U -

Info

Publication number: JPH0328834U
Application number: JP8842789U
Authority: JP
Priority date: 1989-07-27
Filing date: 1989-07-27
Publication date: 1991-03-22
Anticipated expiration: 2004-07-27
Also published as: JP2520762Y2

Description

[Brief explanation of drawings]

第１図は本考案の一実施例を示すブロツク図、
第２図は本考案の他の実施例を示すブロツク図、
第３図、第４図はＰＬＬ回路の従来構成を示すブ
ロツク図である。１０……ＶＣＯ、１１……周波数設定回路、１
２……位相比較回路、１５……基準信号発振器、
１７……ループフイルタ、１８……比較回路、２
２……制限回路。 FIG. 1 is a block diagram showing an embodiment of the present invention.
FIG. 2 is a block diagram showing another embodiment of the present invention;
FIGS. 3 and 4 are block diagrams showing the conventional structure of a PLL circuit. 10...VCO, 11...Frequency setting circuit, 1
2... Phase comparison circuit, 15... Reference signal oscillator,
17...Loop filter, 18...Comparison circuit, 2
2...Limiting circuit.

Claims

[Claims for Utility Model Registration] (1) A variable frequency oscillator whose output signal frequency is varied according to an external signal; and a desired frequency variable oscillator whose output signal frequency is an integral multiple of a reference frequency sampling the output signal from the variable frequency oscillator using the reference signal of the reference frequency and detecting a phase difference with a harmonic component of the reference frequency; a mixer-type phase comparator circuit that outputs a detection signal, and a control signal for controlling the frequency of the output signal from the variable frequency oscillator in a direction to match the desired frequency, from the detection signal, and converting the control signal into the control signal. a loop filter that outputs to the variable frequency oscillator; a comparison circuit that detects that the magnitude of the control signal exceeds a preset limit range; and a comparison circuit that receives the detection signal from the comparison circuit and compares the control signal with A PLL circuit comprising: a limiting circuit that limits the size to within the limit range for a predetermined period of time. (2) The frequency setting means sets the frequency of the variable frequency oscillator to be approximately equal to a desired frequency spaced from an integral multiple of the reference frequency by a predetermined frequency lower than the reference frequency, and A second phase comparator detects the phase difference between the detection signal and the signal of the predetermined frequency, and the second
P according to item 1, wherein the control signal is obtained by the loop filter from the detection signal of the phase comparator.
LL circuit. (3) Clause 1 or 2, wherein the limiting circuit receives a frequency switching signal from the frequency setting means and limits the magnitude of the control signal to be within a limit range for a predetermined time. PLL circuit described in section.