JPS5556712A - Variable gain amplifing circuit - Google Patents

Variable gain amplifing circuit

Info

Publication number
JPS5556712A
JPS5556712A JP13091478A JP13091478A JPS5556712A JP S5556712 A JPS5556712 A JP S5556712A JP 13091478 A JP13091478 A JP 13091478A JP 13091478 A JP13091478 A JP 13091478A JP S5556712 A JPS5556712 A JP S5556712A
Authority
JP
Japan
Prior art keywords
transistor
input
positive
amplifier circuit
variable gain
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.)
Granted
Application number
JP13091478A
Other languages
Japanese (ja)
Other versions
JPS616572B2 (en
Inventor
Kenzo Akagiri
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.)
Sony Corp
Original Assignee
Sony Corp
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 Sony Corp filed Critical Sony Corp
Priority to JP13091478A priority Critical patent/JPS5556712A/en
Publication of JPS5556712A publication Critical patent/JPS5556712A/en
Publication of JPS616572B2 publication Critical patent/JPS616572B2/ja
Granted 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

Landscapes

  • Tone Control, Compression And Expansion, Limiting Amplitude (AREA)
  • Control Of Amplification And Gain Control (AREA)

Abstract

PURPOSE:To simplify the constitution of variable gain amplifier circuit composed of a logarithmic amplifier circuit and reverse-logarithmic amplifier circuit cascaded, by using only one variable impedance transistor. CONSTITUTION:When an input alternating-current voltage is inputted to terminal T1, an output of logarithmic conversion appears at the output side of 1st operational amplifier OP1. At this time, an positive input allows transistor Q1 to operate as a positive transistor and its base is applied with a control signal from input terminal TC. An negative input, on the other hand, supplies the base of transistor Q1 with the control signal from input terminal TC with the output of half-wave rectifier HR added, so that positive and negative impedance characteristics of transistor Q1 will nearly be equal. Further, transistor Q3 operates similarly.
JP13091478A 1978-10-24 1978-10-24 Variable gain amplifing circuit Granted JPS5556712A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP13091478A JPS5556712A (en) 1978-10-24 1978-10-24 Variable gain amplifing circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP13091478A JPS5556712A (en) 1978-10-24 1978-10-24 Variable gain amplifing circuit

Publications (2)

Publication Number Publication Date
JPS5556712A true JPS5556712A (en) 1980-04-25
JPS616572B2 JPS616572B2 (en) 1986-02-27

Family

ID=15045680

Family Applications (1)

Application Number Title Priority Date Filing Date
JP13091478A Granted JPS5556712A (en) 1978-10-24 1978-10-24 Variable gain amplifing circuit

Country Status (1)

Country Link
JP (1) JPS5556712A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4471324A (en) * 1982-01-19 1984-09-11 Dbx, Inc. All NPN variably controlled amplifier

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4471324A (en) * 1982-01-19 1984-09-11 Dbx, Inc. All NPN variably controlled amplifier

Also Published As

Publication number Publication date
JPS616572B2 (en) 1986-02-27

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