WO2001008442A2 - Method and agc device for controlling the amplification of a microphone with an integrated amplifier with a working point which can be adjusted by external wiring - Google Patents

Method and agc device for controlling the amplification of a microphone with an integrated amplifier with a working point which can be adjusted by external wiring Download PDF

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Publication number
WO2001008442A2
WO2001008442A2 PCT/DE2000/001963 DE0001963W WO0108442A2 WO 2001008442 A2 WO2001008442 A2 WO 2001008442A2 DE 0001963 W DE0001963 W DE 0001963W WO 0108442 A2 WO0108442 A2 WO 0108442A2
Authority
WO
WIPO (PCT)
Prior art keywords
microphone
control variable
physical control
sensitivity
frequency response
Prior art date
Application number
PCT/DE2000/001963
Other languages
German (de)
French (fr)
Other versions
WO2001008442A3 (en
Inventor
Roland Aubauer
Ralf Kern
Stefano Ambrosius Klinke
Original Assignee
Siemens Aktiengesellschaft
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 Siemens Aktiengesellschaft filed Critical Siemens Aktiengesellschaft
Priority to AU59653/00A priority Critical patent/AU5965300A/en
Publication of WO2001008442A2 publication Critical patent/WO2001008442A2/en
Publication of WO2001008442A3 publication Critical patent/WO2001008442A3/en

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers without distortion of the input signal
    • H03G3/004—Control by varying the supply voltage
    • 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
    • H04R3/04—Circuits for transducers, loudspeakers or microphones for correcting frequency response
    • H04R3/10—Circuits for transducers, loudspeakers or microphones for correcting frequency response of variable resistance microphones

Definitions

  • Method and AGC device for controlling the amplification of a microphone with an integrated amplifier which can be adjusted by external circuitry
  • the invention relates to a simple control of the sensitivity of microphones with an integrated amplifier, the operating point of which can be set by an external circuit, e.g. a field effect transistor preamplifier (FET preamplifier).
  • FET preamplifier field effect transistor preamplifier
  • the object on which the invention is based is to control the amplification of a microphone with an integrated amplifier, the operating point being adjustable by external circuitry, in such a way that no external controllable amplifier or attenuator is necessary.
  • the idea on which the invention is based is to amplify by changing the microphone sensitivity and / or the microphone frequency response via a microphone supply. voltage or a physical control variable that adjusts a microphone feed impedance.
  • FIGS. 1 to 3 An exemplary embodiment of the invention is explained with reference to FIGS. 1 to 3.
  • FIGURES 1 to 3 each show a circuit for a simple sensitivity and / or frequency response control of electret microphones, which does not require external, controllable amplifiers or attenuators.
  • the simplest implementation is m the sensitivity and frequency response control via the microphone supply voltage U L.
  • the microphone feed impedance Z L is set with a control voltage U s ⁇ .
  • An electronic control of the feed impedance Z L can be carried out, for example, by a controlled field effect transistor.
  • the control range of the microphone sensitivity via the feed impedance is up to 10 dB m depending on the microphone supply voltage.
  • the sensitivity control of microphones with built-in FET preamplifier can also be used advantageously for the automatic control of microphone signals.
  • These circuits are commonly referred to as “Automatic Yarn Con- trol "circuits (AGC device). Applications of these circuits can be found in practically all consumer devices which have a microphone recording channel (cassette recorders, dictation systems, (hands-free) telephones, etc.).

Abstract

In order to control the amplification of a microphone with an integrated amplifier whereby the working point thereof can be adjusted by means of external wiring, so that no externally controllable amplifier or attenuator are required, the sensitivity of said microphone and or frequency response characteristic thereof is modified by means of a microphone supply voltage or a physical control variable which adjusts a microphone feed impedance.

Description

Beschreibungdescription
Verfahren und AGC-Emπchtung zum Steuern der Verstärkung eines Mikrofons mit einem integrierten, den Arbeitspunkt durch externe Beschaltung einstellbaren VerstarkerMethod and AGC device for controlling the amplification of a microphone with an integrated amplifier which can be adjusted by external circuitry
Die Erfindung betrifft eine einfache Steuerung der Empfindlichkeit von Mikrofonen mit integriertem Verstarker, dessen Arbeitspunkt durch eine externe Beschaltung einstellbar ist, z.B. einen Feldeffekttransistor-Vorverstärker (FET- Vorverstarker) .The invention relates to a simple control of the sensitivity of microphones with an integrated amplifier, the operating point of which can be set by an external circuit, e.g. a field effect transistor preamplifier (FET preamplifier).
Bei praktisch allen zur Zeit m Telekommunikations- und Kon- sumeranwendungen verwendeten Mikrofonen bzw. Mikrofonkapseln handelt es sich um Elektretwandler mit integriertem Feldeffekttransistor-Vorverstärker. Dieser Vorverstärker dient zur Verringerung der sehr hohen Mikrofonquellimpedanz und zur Verstärkung des Mikrofonsignals. In der Regel handelt es sich hierbei um die Sourceschaltung eines Feldeffekttransistors. Durch Veränderung der Speiseimpedanz und der Versorgungsspannung laßt sich der Arbeitspunkt des Transistors und damit auch die Empfindlichkeit des Mikrofons andern. Änderungen des Mikrofonfrequenzgangs sind möglich, wenn nicht nur reelle, sondern auch komplexe Speiseimpedanzen zugelassen werden.Practically all the microphones or microphone capsules currently used in telecommunications and consumer applications are electrical converters with an integrated field-effect transistor preamplifier. This preamplifier is used to reduce the very high microphone source impedance and to amplify the microphone signal. As a rule, this is the source circuit of a field effect transistor. By changing the supply impedance and the supply voltage, the operating point of the transistor and thus the sensitivity of the microphone can be changed. Changes in the microphone frequency response are possible if not only real, but also complex feed impedances are permitted.
Die der Erfindung zugrundeliegende Aufgabe besteht darin, die Verstärkung eines Mikrofons mit einem integrierten, den Arbeitspunkt durch externe Beschaltung einstellbaren Verstarker derart zu steuern, daß keine externen steuerbaren Verstarker oder Abschwacher notwendig s nd.The object on which the invention is based is to control the amplification of a microphone with an integrated amplifier, the operating point being adjustable by external circuitry, in such a way that no external controllable amplifier or attenuator is necessary.
Diese Aufgabe wird durch die Merkmale der Patentansprüche 1 und 3 gelost.This object is achieved by the features of claims 1 and 3.
Die der Erfindung zugrundeliegende Idee besteht darin, die Verstärkung durch Verandern der Mikrofonempfmdlichkeit und/oder des Mikrofonfrequenzgangs über eine Mikrofonversor- gungsspannung oder eine physikalische Steuergroße, die eine Mikrofonspeiseimpedanz einstellt, zu steuern.The idea on which the invention is based is to amplify by changing the microphone sensitivity and / or the microphone frequency response via a microphone supply. voltage or a physical control variable that adjusts a microphone feed impedance.
Vorteilhafte Weiterbildungen der Erfindung sind m den Un- teranspruchen angegeben.Advantageous developments of the invention are specified in the subclaims.
Ein Ausfuhrungsbeispiel der Erfindung wird anhand der FIGUREN 1 bis 3 erläutert.An exemplary embodiment of the invention is explained with reference to FIGS. 1 to 3.
Die FIGUREN 1 bis 3 zeigen jeweils eine Schaltung für eine einfache Empfmdlichkeits- und/oder Frequenzgangsteuerung von Elektret-Mikrofonen, die ohne externe, steuerbare Verstarker oder Abschwacher auskommt. Die einfachste Realisierung be- steht m der Empfmdlichkeits- und Frequenzgangsteuerung über die Mikrofonversorgungsspannung UL.FIGURES 1 to 3 each show a circuit for a simple sensitivity and / or frequency response control of electret microphones, which does not require external, controllable amplifiers or attenuators. The simplest implementation is m the sensitivity and frequency response control via the microphone supply voltage U L.
Alternativ ist es auch möglich, die Empfmdlichkeits- und Frequenzgangsteuerung derart zu realisieren, daß die Mikro- fonspeiseimpedanz ZL mit einer Steuerspannung Usτ eingestellt wird.Alternatively, it is also possible to implement the sensitivity and frequency response control in such a way that the microphone feed impedance Z L is set with a control voltage U sτ .
Eine elektronische Steuerung der Speieseimpedanz ZL kann z.B. durch einen gesteuerten Feldeffekttransistor erfolgen. Der Steuerungsbereich der Mikrofonempf dlichkeit über die Speiseimpedanz liegt bei bis zu 10 dB m Abhängigkeit der Mikrofonversorgungsspannung .An electronic control of the feed impedance Z L can be carried out, for example, by a controlled field effect transistor. The control range of the microphone sensitivity via the feed impedance is up to 10 dB m depending on the microphone supply voltage.
Der Vorteil dieser Art der Empf dlichkeits- und Frequenz- gangsteuerung liegt der Minimierung des Schaltungsaufwands und der damit verbundenen Kosten. Der Steuerungsbereich ist für die meisten Anwendungen ausreichend hoch.The advantage of this type of sensitivity and frequency response control is the minimization of circuitry and the associated costs. The control range is sufficiently high for most applications.
Die Empfmdlichkeitssteuerung von Mikrofonen mit eingebautem FET-Vorverstarker kann außerdem vorteilhaft zur automatischen Aussteuerung von Mikrofonsignalen eingesetzt werden. Diese Schaltungen werden im allgemeinen als "Automatic Garn Con- trol"-Schaltungen (AGC-Einrichtung) bezeichnet. Anwendungen dieser Schaltungen finden sich in praktisch allen Konsumergeräten, die einen Mikrofonaufnahmekanal besitzen (Kassettenre- korder, Diktiersysteme, (Freisprech-) Telefone etc.). The sensitivity control of microphones with built-in FET preamplifier can also be used advantageously for the automatic control of microphone signals. These circuits are commonly referred to as "Automatic Yarn Con- trol "circuits (AGC device). Applications of these circuits can be found in practically all consumer devices which have a microphone recording channel (cassette recorders, dictation systems, (hands-free) telephones, etc.).

Claims

Patentansprüche claims
1. Verfahren zum Steuern der Verstärkung eines Mikrofons mit einem integrierten, den Arbeitspunkt durch externe Beschal- tung einstellbaren Verstarker mit folgenden Merkmalen:1. Method for controlling the amplification of a microphone with an integrated amplifier which can be set to the operating point by external circuitry, with the following features:
(a) Aus einer Mikrofonausgangsspannung (Ua) wird eine erste physikalische Steuergroße (STG1) gebildet,(a) A first physical control variable (STG1) is formed from a microphone output voltage (U a ),
(b) mit der ersten physikalischen Steuergroße (STG1) wird (bl) eine Mikrofonversorgungsspannung (UL) zur Änderung der Empfindlichkeit und/oder des Frequenzgangs des Mikrofons (MF) gesteuert, oder(b) with the first physical control variable (STG1) (bl) a microphone supply voltage (U L ) for changing the sensitivity and / or the frequency response of the microphone (MF) is controlled, or
(b2) eine zweite physikalische Steuergroße (Usτ) gesteuert, über die eine Mikrofonspeiseimpedanz (ZL) zur Änderung der Empfindlichkeit und/oder des Frequenzgangs des Mikrofons (MF) eingestellt wird.(b2) controlled a second physical control variable (U sτ ), via which a microphone feed impedance (Z L ) is set to change the sensitivity and / or the frequency response of the microphone (MF).
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß eine Steuerspannung (Usτ) als zweite physikalische Steuergro- ße (USτ) verwendet wird.2. The method according to claim 1, characterized in that a control voltage (U sτ ) is used as the second physical control size (U S τ).
3. AGC-E πchtung zum Steuern der Verstärkung eines Mikrofons mit einem integrierten, den Arbeitspunkt durch externe Beschaltung einstellbaren Verstarker mit folgenden Merkmalen: (a) Steuerungsmittel (STM) für die Verstärkung des Mikrofons (MF) erzeugen aus einer Mikrofonausgangsspannung (Ua) eine erste physikalische Steuergroße (STG1), (b) die Steuerungsmittel (STM) sind (bl) mit einer Spannungsquelle (SQ) , die das Mikrofon (MF) über eine Mikrofonspeiseimpedanz (ZL) mit einer Mikrofonversorgungsspannung (U versorgt, derart verbunden, daß mit der ersten physikalischen Steuergroße (STG1) die Mikrofonversorgungsspannung (UL) zur Änderung der Empfindlichkeit und/oder des Frequenzgangs des Mikrofons (MF) gesteuert wird, oder (b2) mit einer Mikrofonspeiseimpedanz (Z ) des Mikrofons (MF) derart verbunden, daß mit der ersten physikalischen Steuergroße (STG1) eine zweite physikalische Steuergroße (Usτ) ge- steuert wird, über die die Mikrofonspeiseimpedanz (ZL) zur Änderung der Empfindlichkeit und/oder des Frequenzgangs des Mikrofons (MF) eingestellt wird.3. AGC device for controlling the amplification of a microphone with an integrated amplifier which can be set by external circuitry, with the following features: (a) Control means (STM) for amplifying the microphone (MF) generate from a microphone output voltage (U a ) a first physical control variable (STG1), (b) the control means (STM) are (bl) connected to a voltage source (SQ) which supplies the microphone (MF) with a microphone supply voltage (U) via a microphone supply impedance (Z L ), that the microphone supply voltage (U L ) for changing the sensitivity and / or the frequency response of the microphone (MF) is controlled with the first physical control variable (STG1), or (b2) is connected to a microphone feed impedance (Z) of the microphone (MF) in such a way that with the first physical control variable (STG1) a second physical control variable (U sτ ) is controlled, via which the microphone feed impedance (Z L ) for changing the sensitivity and / or the frequency response of the microphone (MF) is set.
-4. AGC-Einrichtung nach Anspruch 3, dadurch gekennzeichnet, daß die Mikrofonspeiseimpedanz (Z ) - gemäß dem Merkmal „(b2)" des Anspruchs 3 - eine Impedanzschaltung ist, bei der ein Feldeffekttransistor (FET) , an dessen Gate-Anschluß bezogen auf ein Bezugspotential als physikalische zweite Steuergröße (OST ) eine Steuerspannung (USτ) anliegt, am Source-Anschluß mit dem Mikrofon (MF) , am Drain-Anschluß mit einem ersten Widerstand (Rl) verbunden ist und bei der parallel zu der Serienschaltung aus Feldeffekttransistor (FET) und erstem Wider- stand (Rl) eine Serienschaltung aus einem zweiten Widerstand (R2), einer Spule (SP) und einem Kondensator (KO) geschaltet ist . -4. AGC device according to claim 3, characterized in that the microphone feed impedance (Z) - according to the feature "(b2)" of claim 3 - is an impedance circuit, in which a field effect transistor (FET), at its gate connection with reference to a reference potential a control voltage (U S τ) is present as the physical second control variable (O S T), is connected to the microphone (MF) at the source connection, is connected to a first resistor (Rl) at the drain connection and is connected in parallel to the series circuit Field effect transistor (FET) and the first resistor (Rl) a series circuit comprising a second resistor (R2), a coil (SP) and a capacitor (KO) is connected.
PCT/DE2000/001963 1999-07-23 2000-06-15 Method and agc device for controlling the amplification of a microphone with an integrated amplifier with a working point which can be adjusted by external wiring WO2001008442A2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU59653/00A AU5965300A (en) 1999-07-23 2000-06-15 Method and agc device for controlling the amplification of microphone with an integrated amplifier with a working point which can be adjusted by external wiring

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19934747.6 1999-07-23
DE1999134747 DE19934747A1 (en) 1999-07-23 1999-07-23 Microphone amplification control method e.g. for telecommunications and consumer applications

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WO2001008442A2 true WO2001008442A2 (en) 2001-02-01
WO2001008442A3 WO2001008442A3 (en) 2001-08-16

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AU (1) AU5965300A (en)
DE (1) DE19934747A1 (en)
WO (1) WO2001008442A2 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2590434A1 (en) * 2011-11-04 2013-05-08 AKG Acoustics GmbH Filter circuit

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2239843A1 (en) * 2009-04-08 2010-10-13 Nxp B.V. Sensitivity adapting transducer

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4617555A (en) * 1985-04-17 1986-10-14 Data Distribution Devices, Inc. Receiver for audible alarm
US5862238A (en) * 1995-09-11 1999-01-19 Starkey Laboratories, Inc. Hearing aid having input and output gain compression circuits

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4617555A (en) * 1985-04-17 1986-10-14 Data Distribution Devices, Inc. Receiver for audible alarm
US5862238A (en) * 1995-09-11 1999-01-19 Starkey Laboratories, Inc. Hearing aid having input and output gain compression circuits

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2590434A1 (en) * 2011-11-04 2013-05-08 AKG Acoustics GmbH Filter circuit
US9204217B2 (en) 2011-11-04 2015-12-01 Akg Acoustics Gmbh Microphone filter system

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WO2001008442A3 (en) 2001-08-16
DE19934747A1 (en) 2001-01-25
AU5965300A (en) 2001-02-13

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