JPS5648726A - Phase locked loop circuit - Google Patents

Phase locked loop circuit

Info

Publication number
JPS5648726A
JPS5648726A JP12393079A JP12393079A JPS5648726A JP S5648726 A JPS5648726 A JP S5648726A JP 12393079 A JP12393079 A JP 12393079A JP 12393079 A JP12393079 A JP 12393079A JP S5648726 A JPS5648726 A JP S5648726A
Authority
JP
Japan
Prior art keywords
input
input data
circuit
phase
signals
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP12393079A
Other languages
Japanese (ja)
Inventor
Masahiro Takahashi
Takushi Hamada
Sadao Mizokawa
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Ltd
Original Assignee
Hitachi Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
Priority to JP12393079A priority Critical patent/JPS5648726A/en
Publication of JPS5648726A publication Critical patent/JPS5648726A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
    • H03L7/00—Automatic control of frequency or phase; Synchronisation
    • H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
    • H03L7/08—Details of the phase-locked loop
    • H03L7/14—Details of the phase-locked loop for assuring constant frequency when supply or correction voltages fail or are interrupted
    • H03L7/143—Details of the phase-locked loop for assuring constant frequency when supply or correction voltages fail or are interrupted by switching the reference signal of the phase-locked loop
    • H03L7/145—Details of the phase-locked loop for assuring constant frequency when supply or correction voltages fail or are interrupted by switching the reference signal of the phase-locked loop the switched reference signal being derived from the controlled oscillator output signal

Landscapes

  • Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)

Abstract

PURPOSE:To prolong the time when a constant frequency can be held even if input data disappear, by providing a multiplexer that alternates inputs to a phase comparing circuit and an input break detecting circuit detecting the existence of input data. CONSTITUTION:Once input data signal (a) disappears due to a transmission fault, etc., input break detecting circuit 6 detects that and with its detection signal, multiplexer 7 is switched to the side output signal (d) of voltage control oscillator 5. Since input signals (c) and (d) to phase comparator 3 are the same signals, they are in phase and comparator 3 generates output signals (e) and (f) of 1 and 0. As a result, the integrating circuit of filter 4 is neigher charged nor discharged to make output voltage (g) constant and the frequency of oscillator 5 is kept constant for a long period until the integrating circuit is discharged by the leakage current of the diode.
JP12393079A 1979-09-28 1979-09-28 Phase locked loop circuit Pending JPS5648726A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP12393079A JPS5648726A (en) 1979-09-28 1979-09-28 Phase locked loop circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP12393079A JPS5648726A (en) 1979-09-28 1979-09-28 Phase locked loop circuit

Publications (1)

Publication Number Publication Date
JPS5648726A true JPS5648726A (en) 1981-05-02

Family

ID=14872857

Family Applications (1)

Application Number Title Priority Date Filing Date
JP12393079A Pending JPS5648726A (en) 1979-09-28 1979-09-28 Phase locked loop circuit

Country Status (1)

Country Link
JP (1) JPS5648726A (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5923926A (en) * 1982-07-30 1984-02-07 Fujitsu Ltd Phase locked loop circuit
DE3302700A1 (en) * 1983-01-27 1984-08-02 Siemens AG, 1000 Berlin und 8000 München CIRCUIT ARRANGEMENT FOR ADJUSTING THE CENTER FREQUENCY OF THE OSCILLATOR OF A PHASE CONTROL CIRCUIT
JPS6212241A (en) * 1985-07-09 1987-01-21 Nec Corp Digital transmission system
JPS6448933U (en) * 1987-09-18 1989-03-27
JPH04365223A (en) * 1991-06-13 1992-12-17 Nec Corp Phase locked loop circuit

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5923926A (en) * 1982-07-30 1984-02-07 Fujitsu Ltd Phase locked loop circuit
JPH0324818B2 (en) * 1982-07-30 1991-04-04 Fujitsu Ltd
DE3302700A1 (en) * 1983-01-27 1984-08-02 Siemens AG, 1000 Berlin und 8000 München CIRCUIT ARRANGEMENT FOR ADJUSTING THE CENTER FREQUENCY OF THE OSCILLATOR OF A PHASE CONTROL CIRCUIT
JPS6212241A (en) * 1985-07-09 1987-01-21 Nec Corp Digital transmission system
JPS6448933U (en) * 1987-09-18 1989-03-27
JPH04365223A (en) * 1991-06-13 1992-12-17 Nec Corp Phase locked loop circuit

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