JPS57203307A - Automatic gain control circuit of photodetecting system - Google Patents

Automatic gain control circuit of photodetecting system

Info

Publication number
JPS57203307A
JPS57203307A JP56087447A JP8744781A JPS57203307A JP S57203307 A JPS57203307 A JP S57203307A JP 56087447 A JP56087447 A JP 56087447A JP 8744781 A JP8744781 A JP 8744781A JP S57203307 A JPS57203307 A JP S57203307A
Authority
JP
Japan
Prior art keywords
circuit
output
controlled
input beam
apd1
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
JP56087447A
Other languages
Japanese (ja)
Inventor
Keiji Nakamura
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.)
NEC Corp
Original Assignee
NEC Corp
Nippon Electric Co 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 NEC Corp, Nippon Electric Co Ltd filed Critical NEC Corp
Priority to JP56087447A priority Critical patent/JPS57203307A/en
Publication of JPS57203307A publication Critical patent/JPS57203307A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers
    • H03G3/20—Automatic control

Landscapes

  • Control Of Amplification And Gain Control (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
  • Optical Communication System (AREA)

Abstract

PURPOSE:To increase the dynamic range of an AGC circuit by means of a simple circuit, by branching the input beam and supplying these beams to both avalanche diode and photodiode. CONSTITUTION:A photodiode PD8 is used in addition to an avalanche photodiode APD1. The several % of the input beam is supplied to the PD8 through a beam branching means 6, and the detecting signal is amplified by a DC amplifier 7. The gain G of an amplifying circuit 2 is controlled by the output the amplifier 7. While the output of the circuit 2 receives the peak detection through a waveheight detecting circuit 4, and the magnification ratio M of the APD1 is controlled by the output which passed through a DC/DC converting circuit. Based on the result of the control of the ratio M, the gain of the amplifier 2 is controlled by the output of the PD8 at a high input beam level. At the same time, the amplification factor of the APD1 is controlled at a low input beam level. Thus the amplitude is set constant for an output signal OUT. In such way, the dynamic range of an AGC circuit is increased with a simple circuit.
JP56087447A 1981-06-09 1981-06-09 Automatic gain control circuit of photodetecting system Pending JPS57203307A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP56087447A JPS57203307A (en) 1981-06-09 1981-06-09 Automatic gain control circuit of photodetecting system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP56087447A JPS57203307A (en) 1981-06-09 1981-06-09 Automatic gain control circuit of photodetecting system

Publications (1)

Publication Number Publication Date
JPS57203307A true JPS57203307A (en) 1982-12-13

Family

ID=13915106

Family Applications (1)

Application Number Title Priority Date Filing Date
JP56087447A Pending JPS57203307A (en) 1981-06-09 1981-06-09 Automatic gain control circuit of photodetecting system

Country Status (1)

Country Link
JP (1) JPS57203307A (en)

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