JPS57143908A - Variable gain amplifying circuit - Google Patents

Variable gain amplifying circuit

Info

Publication number
JPS57143908A
JPS57143908A JP2915881A JP2915881A JPS57143908A JP S57143908 A JPS57143908 A JP S57143908A JP 2915881 A JP2915881 A JP 2915881A JP 2915881 A JP2915881 A JP 2915881A JP S57143908 A JPS57143908 A JP S57143908A
Authority
JP
Japan
Prior art keywords
trs
variation
base
operation point
voltage
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
JP2915881A
Other languages
Japanese (ja)
Inventor
Kazuo Yamaguchi
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.)
Fujitsu Ltd
Original Assignee
Fujitsu 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 Fujitsu Ltd filed Critical Fujitsu Ltd
Priority to JP2915881A priority Critical patent/JPS57143908A/en
Publication of JPS57143908A publication Critical patent/JPS57143908A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G1/00—Details of arrangements for controlling amplification
    • H03G1/0005—Circuits characterised by the type of controlling devices operated by a controlling current or voltage signal
    • H03G1/0017—Circuits characterised by the type of controlling devices operated by a controlling current or voltage signal the device being at least one of the amplifying solid state elements of the amplifier
    • H03G1/0023—Circuits characterised by the type of controlling devices operated by a controlling current or voltage signal the device being at least one of the amplifying solid state elements of the amplifier in emitter-coupled or cascode amplifiers

Landscapes

  • Control Of Amplification And Gain Control (AREA)

Abstract

PURPOSE:To suppress the variation of the operation point of a differential output, by powering up a differential couple of transistors (TR), brought under the voltage control of another differential couple of TRs, through a TR for compensating the variation of an operation point, in a variable gain amplifying circuit unsed for an optical repeater. CONSTITUTION:An input signal IN is applied to the bases of a differential couple of TRs Q1 and Q2; and a control voltage Va is applied to the base of a TRQ3, and a reference voltage Vr is applied to the base of a TRQ4. To the base of a TRQ5 serving as a current source, a bias voltage Vb is applied. The emitter of a TRQ20 for compensating the variation of an operation point is connected to the collectors of the TRs Q1 and Q2 through resistances (R) 1 and 2, and its base is connected to the collector of the TRQ3 and also connected to a power source +V through an R20. An output signal OUT appears at the collectors of the TRs Q1 and Q2. The resistance value of the R20 is set a half the resistance values of the R1 and R2 and even when the control voltage Va is varied, the variation of the operation point of the output signal OUT is suppressed.
JP2915881A 1981-02-28 1981-02-28 Variable gain amplifying circuit Pending JPS57143908A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2915881A JPS57143908A (en) 1981-02-28 1981-02-28 Variable gain amplifying circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2915881A JPS57143908A (en) 1981-02-28 1981-02-28 Variable gain amplifying circuit

Publications (1)

Publication Number Publication Date
JPS57143908A true JPS57143908A (en) 1982-09-06

Family

ID=12268447

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2915881A Pending JPS57143908A (en) 1981-02-28 1981-02-28 Variable gain amplifying circuit

Country Status (1)

Country Link
JP (1) JPS57143908A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100404270B1 (en) * 1999-04-23 2003-11-03 엔이씨 일렉트로닉스 코포레이션 Gamma conversion circuit changeable gain rate and amplifing capable range thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100404270B1 (en) * 1999-04-23 2003-11-03 엔이씨 일렉트로닉스 코포레이션 Gamma conversion circuit changeable gain rate and amplifing capable range thereof

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