JPH02111937U

JPH02111937U -

Info

Publication number: JPH02111937U
Application number: JP1916089U
Authority: JP
Priority date: 1989-02-21
Filing date: 1989-02-21
Publication date: 1990-09-07

Description

[Brief explanation of drawings]

第１図はこの考案の一実施例を示すＰＬＬ発振
器の構成図、第２図はこの考案の一実施例を示す
ＰＬＬ発振器に用いられているループフイルタの
回路図、第３図は従来のＰＬＬ発振器の構成図、
第４図は従来のＰＬＬ発振器に用いられているル
ープフイルタの回路図、第５図は基準信号源とＶ
ＣＯの出力信号の位相雑音特性図、第６図はルー
プフイルタの利得特性図である。図において、１は基準信号源、２はＶＣＯ、３
は位相検波器、４はスイープ回路、５は帯域通過
フイルタ、６は信号レベル検出器、７はロツク判
定回路、８はループフイルタ、９は演算増幅器、
１０，１１，１２，１３，１６は抵抗、１４はコ
ンデンサ、１５はアナログスイツチ、１７はルー
プフイルタ、イは出力端子、ロは入力端子、ハは
出力端子、ニは論理入力端子である。なお、図中
同一符号は同一または相当部分を示す。 Fig. 1 is a block diagram of a PLL oscillator showing an embodiment of this invention, Fig. 2 is a circuit diagram of a loop filter used in a PLL oscillator showing an embodiment of this invention, and Fig. 3 is a diagram of a conventional PLL oscillator. Oscillator configuration diagram,
Figure 4 is a circuit diagram of a loop filter used in a conventional PLL oscillator, and Figure 5 is a reference signal source and V
FIG. 6 is a phase noise characteristic diagram of the output signal of the CO, and FIG. 6 is a gain characteristic diagram of the loop filter. In the figure, 1 is the reference signal source, 2 is the VCO, and 3
is a phase detector, 4 is a sweep circuit, 5 is a band pass filter, 6 is a signal level detector, 7 is a lock determination circuit, 8 is a loop filter, 9 is an operational amplifier,
10, 11, 12, 13, and 16 are resistors, 14 is a capacitor, 15 is an analog switch, 17 is a loop filter, A is an output terminal, B is an input terminal, C is an output terminal, and D is a logic input terminal. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims

[Scope of utility model registration request]

comparing a reference signal source, a voltage controlled oscillator whose oscillation frequency changes in response to a control voltage, and phases of output signals of the reference signal source and the voltage controlled oscillator;
a phase detector that outputs an error voltage; a sweep circuit that sweeps when the output signal of the voltage controlled oscillator is not phase synchronized with the output signal of the reference signal source; It consists of a bandpass filter that performs bandpass filtering and a signal level detector that detects the level of the output signal of the bandpass filter, and determines whether the output signal of the voltage controlled oscillator is phase-locked with the output signal of the reference signal source. A lock judgment circuit that judges and displays the result, a resistor between the non-inverting input terminal of the operational amplifier and the ground point, a series circuit of a resistor and a capacitor between the inverting input terminal and the output terminal, and a series circuit of a resistor and a capacitor in parallel. A loop filter has a circuit in which an analog switch and a resistor are connected in parallel to the inverting input terminal, and a resistor is further connected in series, with one end open, and the transfer characteristic changes according to the output of the lock determination circuit. A PLL (
Phase-Locked Loop) oscillator.