FR2434538A1 - Colour TV voltage locking circuit - discharges, reference voltage capacitor through current reflector controlled by differential amplifier to avoid problems of drift - Google Patents

Colour TV voltage locking circuit - discharges, reference voltage capacitor through current reflector controlled by differential amplifier to avoid problems of drift

Info

Publication number
FR2434538A1
FR2434538A1 FR7824432A FR7824432A FR2434538A1 FR 2434538 A1 FR2434538 A1 FR 2434538A1 FR 7824432 A FR7824432 A FR 7824432A FR 7824432 A FR7824432 A FR 7824432A FR 2434538 A1 FR2434538 A1 FR 2434538A1
Authority
FR
France
Prior art keywords
capacitor
voltage
current
reference voltage
colour
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
FR7824432A
Other languages
French (fr)
Inventor
Jean-Claude Rufray
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.)
Thales SA
Original Assignee
Thomson CSF SA
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 Thomson CSF SA filed Critical Thomson CSF SA
Priority to FR7824432A priority Critical patent/FR2434538A1/en
Publication of FR2434538A1 publication Critical patent/FR2434538A1/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/30—Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters
    • H03F1/303—Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters using a switching device
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/14—Picture signal circuitry for video frequency region
    • H04N5/16—Circuitry for reinsertion of dc and slowly varying components of signal; Circuitry for preservation of black or white level
    • H04N5/18—Circuitry for reinsertion of dc and slowly varying components of signal; Circuitry for preservation of black or white level by means of "clamp" circuit operated by switching circuit

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Power Engineering (AREA)
  • Processing Of Color Television Signals (AREA)
  • Picture Signal Circuits (AREA)

Abstract

A locking voltage circuit, for example for a colour t.v. receives a video signal at its input (61) which is passed through a capacitor (C1) which sets a reference voltage, and a positive or negative gain high impedance amplifier (A) to provide at the circuit output (62) a constant value locking voltage (Vs). The capacitor (C1) normally discharges through a parallel resistor which introduces drift problems. Here discharge through a comparator circuit comprising a current reflector (66) controlled by a differential amplifier (63) one input (T1) of which measures the amplifier output voltage while the other (T2) receives a fixed reference voltage proportional to the locking voltage. The current reflector supplies current to the capacitor (C1) while the amplifier output voltage is equal to the locking voltage, the discharge current of the capacitor (C1) passing solely through and controlled by the current reflector (66). The comparator circuit absorbs the capacitor discharge current and then blocks itself during the line sweep period.
FR7824432A 1978-08-23 1978-08-23 Colour TV voltage locking circuit - discharges, reference voltage capacitor through current reflector controlled by differential amplifier to avoid problems of drift Pending FR2434538A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
FR7824432A FR2434538A1 (en) 1978-08-23 1978-08-23 Colour TV voltage locking circuit - discharges, reference voltage capacitor through current reflector controlled by differential amplifier to avoid problems of drift

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7824432A FR2434538A1 (en) 1978-08-23 1978-08-23 Colour TV voltage locking circuit - discharges, reference voltage capacitor through current reflector controlled by differential amplifier to avoid problems of drift

Publications (1)

Publication Number Publication Date
FR2434538A1 true FR2434538A1 (en) 1980-03-21

Family

ID=9212018

Family Applications (1)

Application Number Title Priority Date Filing Date
FR7824432A Pending FR2434538A1 (en) 1978-08-23 1978-08-23 Colour TV voltage locking circuit - discharges, reference voltage capacitor through current reflector controlled by differential amplifier to avoid problems of drift

Country Status (1)

Country Link
FR (1) FR2434538A1 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0040274A1 (en) * 1980-05-20 1981-11-25 Motorola, Inc. Self balancing modulator and its application in a chroma demodulator
FR2599852A1 (en) * 1986-06-06 1987-12-11 Labo Electronique Physique INPUT CIRCUIT FOR LOGIC ANALYZER PROBE, AND LOGIC PROBE AND ANALYZER HAVING SUCH A CIRCUIT
EP0491186A1 (en) * 1990-12-13 1992-06-24 Motorola, Inc. Clamp circuit
EP0660509A1 (en) * 1993-12-23 1995-06-28 STMicroelectronics S.A. Amplifier with offset correction

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2309100A1 (en) * 1975-08-27 1976-11-19 Rca Corp AMPLIFIER THAT CAN BE USED AS ATTACK STAGE OF A COLOR IMAGE TUBE

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2309100A1 (en) * 1975-08-27 1976-11-19 Rca Corp AMPLIFIER THAT CAN BE USED AS ATTACK STAGE OF A COLOR IMAGE TUBE

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0040274A1 (en) * 1980-05-20 1981-11-25 Motorola, Inc. Self balancing modulator and its application in a chroma demodulator
FR2599852A1 (en) * 1986-06-06 1987-12-11 Labo Electronique Physique INPUT CIRCUIT FOR LOGIC ANALYZER PROBE, AND LOGIC PROBE AND ANALYZER HAVING SUCH A CIRCUIT
EP0252538A1 (en) * 1986-06-06 1988-01-13 Laboratoires D'electronique Philips Entry circuit for a logic analyser probe, and logic analyser probe provided with such a circuit
EP0491186A1 (en) * 1990-12-13 1992-06-24 Motorola, Inc. Clamp circuit
EP0660509A1 (en) * 1993-12-23 1995-06-28 STMicroelectronics S.A. Amplifier with offset correction
FR2714548A1 (en) * 1993-12-23 1995-06-30 Sgs Thomson Microelectronics Amplifier with offset voltage correction.
US5508656A (en) * 1993-12-23 1996-04-16 Sgs-Thomson Microelectronics S.A. Amplifier with offset correction

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