JPH0434027U

JPH0434027U -

Info

Publication number: JPH0434027U
Application number: JP7518590U
Authority: JP
Priority date: 1990-07-17
Filing date: 1990-07-17
Publication date: 1992-03-19

Description

[Brief explanation of the drawing]

第１図はこの考案に係るロツクアツプタイム短
縮のフエーズロツクドループ回路の実施例を示す
フエーズロツクドループ回路を構成するループフ
イルタ回路図である。第２図及び第３図は従来例
を示し、第２図はフエーズロツクドループ周波数
シンセサイザを示す構成ブロツク図、第３図はル
ープフイルタの回路図である。主な符号の説明、２……電圧制御発振回路、６
……位相比較器、７……周波数制御信号入力端子
、Ｑ_１，Ｑ_２……トランジスタ、Ｒ_１〜Ｒ_６……
抵抗、Ｃ_１，Ｃ_２……コンデンサ。 FIG. 1 is a loop filter circuit diagram constituting a phase-locked loop circuit showing an embodiment of the phase-locked loop circuit for shortening lock-up time according to the present invention. 2 and 3 show a conventional example. FIG. 2 is a block diagram showing a phase-locked loop frequency synthesizer, and FIG. 3 is a circuit diagram of a loop filter. Explanation of main symbols, 2... Voltage controlled oscillation circuit, 6
... Phase comparator, 7 ... Frequency control signal input terminal, Q ₁ , Q ₂ ... Transistor, R ₁ to _{R 6} ...
Resistor, C ₁ , C ₂ ... capacitor.

Claims

[Claims for Utility Model Registration] In a phase-locked loop PLL circuit comprising a reference frequency oscillator, a phase comparator, a voltage-controlled oscillator, and a loop filter, a resistor that is a component of the phase-locked loop circuit A differential circuit and a switching circuit using a transistor are provided in a loop filter consisting of a capacitor and a transistor, and the time constant of the loop filter is changed by turning ON/OFF the switching circuit to shorten the lock-up time. A phase-locked loop circuit that shortens lock-up time.