WO2003086014A1 - Convertisseur d'impedance pour microphone de condensateur - Google Patents

Convertisseur d'impedance pour microphone de condensateur Download PDF

Info

Publication number
WO2003086014A1
WO2003086014A1 PCT/JP2002/003623 JP0203623W WO03086014A1 WO 2003086014 A1 WO2003086014 A1 WO 2003086014A1 JP 0203623 W JP0203623 W JP 0203623W WO 03086014 A1 WO03086014 A1 WO 03086014A1
Authority
WO
WIPO (PCT)
Prior art keywords
capacitor
impedance converter
source follower
resistor
power supply
Prior art date
Application number
PCT/JP2002/003623
Other languages
English (en)
Japanese (ja)
Inventor
Takashi Yamasaki
Original Assignee
Rion 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 Rion Co.,Ltd filed Critical Rion Co.,Ltd
Priority to AU2002255260A priority Critical patent/AU2002255260A1/en
Priority to JP2003583055A priority patent/JP4024213B2/ja
Priority to PCT/JP2002/003623 priority patent/WO2003086014A1/fr
Publication of WO2003086014A1 publication Critical patent/WO2003086014A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/50—Amplifiers in which input is applied to, or output is derived from, an impedance common to input and output circuits of the amplifying element, e.g. cathode follower
    • H03F3/505—Amplifiers in which input is applied to, or output is derived from, an impedance common to input and output circuits of the amplifying element, e.g. cathode follower with field-effect devices
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/181—Low-frequency amplifiers, e.g. audio preamplifiers
    • H03F3/183—Low-frequency amplifiers, e.g. audio preamplifiers with semiconductor devices only
    • H03F3/185—Low-frequency amplifiers, e.g. audio preamplifiers with semiconductor devices only with field-effect devices
    • H03F3/1855—Low-frequency amplifiers, e.g. audio preamplifiers with semiconductor devices only with field-effect devices with junction-FET devices
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/03—Indexing scheme relating to amplifiers the amplifier being designed for audio applications
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/219—Follower transistors are added at the input of the amplifier, e.g. source or emitter followers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/222—A circuit being added at the input of an amplifier to adapt the input impedance of the amplifier

Definitions

  • the present invention relates to an impedance converter incorporated in a small condenser microphone used for a hearing aid or the like.
  • a source follower circuit using a field effect transistor FET
  • FET field effect transistor
  • the impedance converter has a JFET or M ⁇ ⁇ ⁇ SFET transistor chip mounted on a ceramic substrate, a firing resistor is formed on the ceramic substrate, and a chip component is mounted on the capacitor. Or, it was realized as a hybrid circuit by forming a ferroelectric film on a ceramics substrate by sandwiching it between vapor deposition layers.
  • the impedance converter is formed as a hybrid circuit on a ceramic substrate
  • the size of the hybrid circuit formed on the ceramic substrate hinders miniaturization when the hearing aid microphone is miniaturized.
  • the present invention has been made in view of the above-mentioned problems of the conventional technology, and an object thereof is to prevent a surge voltage such as electrostatic discharge from being directly applied to a capacitor, and to provide a capacitor having a low withstand voltage.
  • the aim is to provide an impedance converter for condenser microphones that can withstand surge voltages and that can be downsized.
  • the invention according to claim 1 is an impedance converter for reducing an output impedance of a condenser microphone with respect to an electric signal, and uses a field effect transistor (FET).
  • FET field effect transistor
  • a source follower circuit is provided, and resistors Rl and R2 are connected in series to a power supply line and an output signal line of the source follower circuit, respectively, and the power supply on the source follower circuit side of these resistors Rl and R2 is provided.
  • Capacitors C1 and C2 were connected between the line and output signal line and Durand line, respectively.
  • An invention according to claim 2 is the impedance converter for a condenser microphone according to claim 1, wherein the filter includes a resistor R1 connected to the power supply line and a capacitor C1.
  • the cut-off frequency of the circuit and the cut-off frequency of the filter circuit constituted by the resistor R2 and the capacitor C2 connected to the output signal line were made substantially equal.
  • the invention according to claim 3 is the impedance converter for a capacitor microphone according to claim 1 or 2, comprising the source follower circuit, the resistor R1, and the capacitor C1. And a filter circuit composed of the resistor R2 and the capacitor C2 are formed in one chip on the same silicon substrate.
  • FIG. 1 is a circuit diagram of an impedance converter for a condenser microphone according to the present invention.
  • FIG. 1 is a circuit diagram of an impedance converter for a condenser microphone according to the present invention.
  • an impedance converter 1 for a condenser microphone according to the present invention includes a source follower circuit 5 including a field effect transistor (FET) 2 and resistors 3 and 4, and a power supply line 6 of the source follower circuit 5.
  • FET field effect transistor
  • the resistors R1 and R2 connected in series to the output signal line 7, respectively, and the resistors R1 and R2 connected between the power supply line 6 on the source follower circuit 5 side and the output signal line 7 and the ground line 8, respectively.
  • It has capacitors C1 and C2.
  • 9 is a condenser microphone
  • 10 is a power supply terminal
  • 11 is an output terminal
  • 12 is a ground terminal.
  • a one-pass filter circuit 13 is formed by the resistor R1 and the capacitor C1 connected to the power supply line 6, and a one-pass filter circuit 14 is formed by the resistor R2 and the capacitor C2 connected to the output signal line 7.
  • the cut-off frequency of the low-pass filter circuit 13 and the cut-off frequency of the low-pass filter circuit 14 are equal, and the cut-off frequency is lower than the frequency of the high-frequency electromagnetic waves received as jamming radio waves.
  • the value of the capacitance of C2 is determined.
  • the resistance value of the resistor R1 and the resistance value of the resistor R2 may not be equal, and the capacitance value of the capacitor C1 and the capacitance value of the capacitor C2 may not be equal.
  • the acoustic signal is converted into an electric signal by the condenser microphone 9, and the obtained electric signal is input to the FET 2 of the source follower circuit 5. Then, the output impedance of the condenser microphone 9 with respect to the electric signal is reduced by the FET2. The electric signal is output from the output terminal 11 via the resistor R2 and the output signal line 7.
  • the source follower circuit 5 can carry out impedance conversion of the electric signal from the condenser microphone 9 and detect it from the output terminal 11 without detecting the interfering radio wave due to the high-frequency electromagnetic wave.
  • the surge voltage is first applied to the resistors R 1 and R 2, and heat energy is generated inside the resistors R l and R 2.
  • the surge voltage is applied to the capacitors CI and C2 with their peak value reduced.
  • the surge voltage is not directly applied to the capacitors CI and C2, so there is no need to provide a high withstand voltage, and the capacitors C1 and C2 do not require excessive quality unrelated to the function of the impedance converter. I'm done.
  • the resistance value of the resistors R l and R 2 increases.
  • the impedance converter is a battery-powered hearing aid. When used in such devices, it is equivalent to increasing the internal resistance of the battery, so applying it to them is disadvantageous. Therefore, when the impedance converter is applied to a battery-driven product such as a hearing aid, the resistance value of the resistor R1 provided on the power supply line 6 needs to be reduced to such an extent that it is not disadvantageous in use. Further, even if the resistance value of the resistor R2 provided in the output signal line 7 is not as small as the resistance value of the resistor R1, the influence on the applied device is small.
  • the resistance of the resistor R 2 can be increased to make it more robust against surge voltages. Therefore, the resistance value of the resistor R1 provided on the power supply line 6 and the resistance value of the resistor R2 provided on the output signal line 7 do not need to be equal.
  • the impedance converter 1 for a condenser microphone includes a source follower circuit 5, a low-pass filter circuit 13 including a resistor R1 and a capacitor Cn, a resistor R2 and a capacitor C2.
  • One-pass filter circuit 14 is formed in one chip on the same silicon substrate. The size of the crophone can be easily reduced. Industrial applicability
  • the surge voltage is first applied to the resistors R1 and R2, The surge voltage is consumed as heat energy inside the resistors R l and R 2, and the surge voltage is applied to the capacitors C l and C 2 with their peak values reduced, so that the surge voltage is applied to the capacitors C l and C 2. Since it is not applied directly, there is no need to provide a high withstand voltage, and capacitors C l and C 2 do not need to have excessive quality that is not related to the function of the impedance converter.
  • the disturbing radio wave caused by the high-frequency electromagnetic wave between the power supply line and the ground line and the disturbing radio wave caused by the high-frequency electromagnetic wave between the output signal line and the ground line are reduced equally.
  • noise output from the source follower circuit due to high-frequency electromagnetic waves can be prevented.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Multimedia (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
  • Circuit For Audible Band Transducer (AREA)
  • Amplifiers (AREA)

Abstract

L'invention concerne un convertisseur d'impédance pour un microphone de condensateur, dans lequel une tension transitoire de décharge électrostatique, ou analogue, n'est pas appliquée directement à un condensateur, et même à un condensateur présentant une tension de résistance faible. Ce condensateur peut résister à la tension transitoire tout en en réduisant la taille. Le convertisseur d'impédance (1) permet de réduire l'impédance de sortie au niveau du signal électrique d'un microphone de condensateur (9) et comprend un circuit suiveur source (5) faisant appel à un transistor à effet de champ (FET) (2). Ce circuit suiveur source (5) comporte une ligne d'alimentation (6) et une ligne de signal de sortie (7) reliées en série, respectivement à des résistances R1 et R2, des condensateurs C1 et C2 étant connectés entre, respectivement, une ligne de terre (8), et la ligne d'alimentation (6), et la ligne de signal de sortie (7), du côté des résistances R1 et R2 du circuit suiveur source (5).
PCT/JP2002/003623 2002-04-11 2002-04-11 Convertisseur d'impedance pour microphone de condensateur WO2003086014A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
AU2002255260A AU2002255260A1 (en) 2002-04-11 2002-04-11 Impedance converter for capacitor microphone
JP2003583055A JP4024213B2 (ja) 2002-04-11 2002-04-11 コンデンサマイクロホン用インピーダンス変換器
PCT/JP2002/003623 WO2003086014A1 (fr) 2002-04-11 2002-04-11 Convertisseur d'impedance pour microphone de condensateur

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2002/003623 WO2003086014A1 (fr) 2002-04-11 2002-04-11 Convertisseur d'impedance pour microphone de condensateur

Publications (1)

Publication Number Publication Date
WO2003086014A1 true WO2003086014A1 (fr) 2003-10-16

Family

ID=28694870

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2002/003623 WO2003086014A1 (fr) 2002-04-11 2002-04-11 Convertisseur d'impedance pour microphone de condensateur

Country Status (3)

Country Link
JP (1) JP4024213B2 (fr)
AU (1) AU2002255260A1 (fr)
WO (1) WO2003086014A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2104373A1 (fr) * 2008-03-13 2009-09-23 Kabushiki Kaisha Audio- Technica Microphone à condensateur

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4280018A (en) * 1979-05-14 1981-07-21 Strobotronix, Inc. Integrated piezoelectric sound transducer and preamplifier
JPS61128615A (ja) * 1984-11-28 1986-06-16 Matsushita Electric Ind Co Ltd ヘツドアンプ
US4993072A (en) * 1989-02-24 1991-02-12 Lectret S.A. Shielded electret transducer and method of making the same
US6084972A (en) * 1996-04-03 2000-07-04 Microtronic Nederland B.V. Integrated microphone/amplifier unit, and amplifier module therefor

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4280018A (en) * 1979-05-14 1981-07-21 Strobotronix, Inc. Integrated piezoelectric sound transducer and preamplifier
JPS61128615A (ja) * 1984-11-28 1986-06-16 Matsushita Electric Ind Co Ltd ヘツドアンプ
US4993072A (en) * 1989-02-24 1991-02-12 Lectret S.A. Shielded electret transducer and method of making the same
US6084972A (en) * 1996-04-03 2000-07-04 Microtronic Nederland B.V. Integrated microphone/amplifier unit, and amplifier module therefor

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2104373A1 (fr) * 2008-03-13 2009-09-23 Kabushiki Kaisha Audio- Technica Microphone à condensateur
JP2009224839A (ja) * 2008-03-13 2009-10-01 Audio Technica Corp コンデンサーマイクロホン
US8126165B2 (en) 2008-03-13 2012-02-28 Kabushiki Kaisha Audio-Technica Condenser microphone

Also Published As

Publication number Publication date
AU2002255260A1 (en) 2003-10-20
JP4024213B2 (ja) 2007-12-19
JPWO2003086014A1 (ja) 2005-08-18

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