JP4741356B2 - Microphone amplifier - Google Patents

Microphone amplifier Download PDF

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JP4741356B2
JP4741356B2 JP2005349881A JP2005349881A JP4741356B2 JP 4741356 B2 JP4741356 B2 JP 4741356B2 JP 2005349881 A JP2005349881 A JP 2005349881A JP 2005349881 A JP2005349881 A JP 2005349881A JP 4741356 B2 JP4741356 B2 JP 4741356B2
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power supply
amplifier
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JP2007158629A (en
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直幸 本木
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New Japan Radio Co Ltd
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New Japan Radio Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To maximally and efficiently swing an output voltage within a voltage range from a ground potential GND to an external power-supply voltage VDD. <P>SOLUTION: A microphone amplifier has an input terminal 11 connected to a microphone 1, an output terminal 12 connected to an external power-supply terminal 3 through a load resistor 2 and a ground terminal 13 connected to a ground. The microphone amplifier further has an amplifier 14 amplifying a signal input to the input terminal 11 and a driving circuit 15 driving the output terminal 12 by inputting an output signal from the amplifier 14. An internal power-supply terminal 18 for connecting a capacitor 4 between the microphone amplifier and the ground, and the internal power-supply terminal 18 is connected at a power-supply terminal for the amplifier 14 while the series circuit of a current-limiting circuit 17 and a diode 16 is connected between the internal power-supply terminal 18 and the output terminal 12. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

本発明は、マイクロホンの出力信号を入力して増幅するマイク増幅器に関するものである。  The present invention relates to a microphone amplifier that inputs and amplifies a microphone output signal.

従来のマイク増幅器１０Ａの構成を図３に示す（類似の技術として例えば、特許文献１，非特許文献１参照）。このマイク増幅器１０Ａは、マイクロホン１に接続される入力端子１１と、負荷抵抗２を介して外部電源電圧ＶＤＤの外部電源端子３に接続される出力端子１２と、接地に接続される接地端子１３と、入力端子１１に入力する信号を増幅する増幅回路１４と、その増幅回路１４の出力信号を入力して出力端子１２を駆動するドライブ回路１５とを備える。  A configuration of a conventional microphone amplifier 10A is shown in FIG. 3 (see, for example, Patent Document 1 and Non-Patent Document 1 as similar techniques). The microphone amplifier 10A includes an input terminal 11 connected to the microphone 1, an output terminal 12 connected to the external power supply terminal 3 of the external power supply voltage VDD via the load resistor 2, and a ground terminal 13 connected to the ground. The amplifier circuit 14 amplifies the signal input to the input terminal 11, and the drive circuit 15 that inputs the output signal of the amplifier circuit 14 and drives the output terminal 12.

このマイク増幅器１０Ａでは、マイクロホン１から入力する信号が増幅されて駆動回路１５のドレイン電流が変化し、これが負荷抵抗２に流れることにより、出力端子１２の電圧Ｖoutが変化する。
特開昭５７−０６９９１２号公報 米国特許第６，１６０，４５０号明細書 In the microphone amplifier 10A, the signal input from the microphone 1 is amplified and the drain current of the drive circuit 15 changes, and when this flows to the load resistor 2, the voltage Vout of the output terminal 12 changes.
JP 57-069912 A US Pat. No. 6,160,450

ところが、図３のマイク増幅器１０Ａは、出力端子１２の電圧Voutがそのまま増幅回路１４の電源電圧Vampとしてその増幅回路１４の電源端子に印加されるため、その出力端子１２の出力電圧Ｖoutによって増幅回路１４の電源電圧Vampが変動する。したがって、出力端子１２の出力電圧Ｖoutが増幅回路１４の最低動作電圧Ｖmoよりも低くなる（Vmo＞Vout）ような駆動を行わせることができず、出力電圧Voutを接地電位ＧＮＤから外部電源電圧ＶＤＤまでの電圧範囲で目一杯効率よくスイングさせることができないという問題があった。図４はこれを説明するための波形図である。  However, in the microphone amplifier 10A of FIG. 3, since the voltage Vout of the output terminal 12 is applied as it is to the power supply terminal of the amplifier circuit 14 as the power supply voltage Vamp of the amplifier circuit 14, the amplifier circuit is driven by the output voltage Vout of the output terminal 12. 14 power supply voltage Vamp fluctuates. Therefore, it is impossible to drive the output terminal 12 so that the output voltage Vout of the output terminal 12 is lower than the minimum operating voltage Vmo of the amplifier circuit 14 (Vmo> Vout), and the output voltage Vout is changed from the ground potential GND to the external power supply voltage VDD. There was a problem that it was not possible to swing fully efficiently in the voltage range up to. FIG. 4 is a waveform diagram for explaining this.

本発明の目的は、出力電圧を接地電位から外部電源電圧までの電圧範囲で目一杯効率よくスイングさせることができるようにしたマイク増幅器を提供することである。  An object of the present invention is to provide a microphone amplifier that can swing an output voltage fully and efficiently in a voltage range from a ground potential to an external power supply voltage.

上記目的を達成するために、請求項１にかかる発明は、マイクロホンに接続される入力端子と、負荷抵抗を介して外部電源端子に接続される出力端子と、接地に接続される接地端子と、前記入力端子に入力する信号を増幅する増幅回路と、該増幅回路の出力信号を入力して前記出力端子を駆動するドライブ回路とを備えたマイク増幅器において、内部電源端子を設け、該内部電源端子と前記接地との間にキャパシタを接続し、前記内部電源端子を前記増幅回路の電源端子に接続すると共に、前記内部電源端子と前記出力端子との間に限流回路とダイオードの直列回路を接続し、前記負荷抵抗に流れる前記ドライブ回路の出力電流が前記限流回路とダイオードで検波されてから前記キャパシタで積分され、該キャパシタで得られた電圧が前記増幅回路の電源電圧となるようにしたことを特徴とする。
請求項２にかかる発明は、請求項１に記載のマイク増幅器において、前記ダイオードはそのアノードが前記出力端子側となるように接続されていることを特徴とする。

In order to achieve the above object, an invention according to claim 1 includes an input terminal connected to a microphone, an output terminal connected to an external power supply terminal via a load resistor, a ground terminal connected to ground, In a microphone amplifier comprising an amplifier circuit for amplifying a signal input to the input terminal and a drive circuit for inputting the output signal of the amplifier circuit and driving the output terminal, an internal power supply terminal is provided, and the internal power supply terminal connection with external capacitor, connected to said internal power supply terminal to the power supply terminal of the amplifier circuit, a series circuit of a current limiting circuit and a diode between the output terminal and the internal power source terminal between the ground and and, the load output current of the drive circuit flowing through the resistor is integrated by the capacitor from being detected by the current limiting circuit and a diode, the voltage obtained by the capacitor is the increase Characterized in that as the power supply voltage of the circuit.
According to a second aspect of the present invention, in the microphone amplifier according to the first aspect, the diode is connected such that an anode thereof is on the output terminal side.

本発明によれば、正の振幅時あるいは無信号時にキャパシタに蓄積された電荷により増幅回路に電源電圧が供給されるため、その増幅回路の電源電圧を必要な電圧に保持させることができ、このため出力端子をその増幅回路の最低動作電圧Ｖmoより低い電圧にまで振らせることができる。すなわち、出力電圧を接地電位ＧＮＤから外部電源電圧ＶＤＤまでの電圧範囲で目一杯効率よくスイングさせることができる。  According to the present invention, since the power supply voltage is supplied to the amplifier circuit by the charge accumulated in the capacitor at the time of positive amplitude or no signal, the power supply voltage of the amplifier circuit can be held at a necessary voltage. Therefore, the output terminal can be swung to a voltage lower than the minimum operating voltage Vmo of the amplifier circuit. That is, the output voltage can be swung with high efficiency in the voltage range from the ground potential GND to the external power supply voltage VDD.

図１は本発明の実施例のマイク増幅器１０の構成を示すブロック図である。このマイク増幅器１０は、マイクロホン１に接続される入力端子１１と、負荷抵抗２を介して外部電源電圧ＶＤＤの外部電源端子３に接続される出力端子１２と、接地に接続される接地端子１３と、入力端子１１に入力する信号を増幅する増幅回路１４と、その増幅回路１４の出力信号を入力して出力端子１２を駆動するドライブ回路１５と、ダイオード１６と限流回路１７の直列回路と、キャパシタ４を介して接地に接続される内部電源端子１８とを備える。この内部電源端子１８は増幅回路１４の電源端子とダイオード１６のカソードに接続される。  FIG. 1 is a block diagram showing a configuration of a microphone amplifier 10 according to an embodiment of the present invention. The microphone amplifier 10 includes an input terminal 11 connected to the microphone 1, an output terminal 12 connected to the external power supply terminal 3 of the external power supply voltage VDD via the load resistor 2, and a ground terminal 13 connected to the ground. An amplifier circuit 14 that amplifies a signal input to the input terminal 11, a drive circuit 15 that inputs an output signal of the amplifier circuit 14 and drives the output terminal 12, a series circuit of a diode 16 and a current limiting circuit 17, And an internal power supply terminal 18 connected to the ground via the capacitor 4. The internal power supply terminal 18 is connected to the power supply terminal of the amplifier circuit 14 and the cathode of the diode 16.

本実施例では、ダイオード１６と限流回路１７が検波回路として機能し、キャパシタ４が積分回路として機能して、キャパシタ４の電圧よりも出力端子１２の出力電圧Ｖoutが高いときのみ、つまり正の振幅時あるいは無信号時に電荷がキャパシタ４に蓄積される。そして、このキャパシタ４に蓄積された電圧は増幅回路１４の電源電圧Vampとして供給される。  In this embodiment, the diode 16 and the current limiting circuit 17 function as a detection circuit, the capacitor 4 functions as an integration circuit, and only when the output voltage Vout of the output terminal 12 is higher than the voltage of the capacitor 4, that is, positive Electric charges are accumulated in the capacitor 4 when the amplitude or no signal is present. The voltage stored in the capacitor 4 is supplied as the power supply voltage Vamp of the amplifier circuit 14.

以上から、増幅回路１４の電源電圧Ｖampは出力電圧Ｖoutから独立して安定化するので、その出力電圧Ｖoutはその増幅回路１４の最低動作電圧Ｖmoを考慮することなく、図２に示すように、接地電位ＧＮＤから外部電源端子３に印加される外部電源電圧ＶＤＤまでの電圧範囲で目一杯効率高くフルスイングさせることができる。  From the above, since the power supply voltage Vamp of the amplifier circuit 14 is stabilized independently of the output voltage Vout, the output voltage Vout does not take into account the minimum operating voltage Vmo of the amplifier circuit 14, as shown in FIG. A full swing can be performed with high efficiency in the voltage range from the ground potential GND to the external power supply voltage VDD applied to the external power supply terminal 3.

本発明の実施例のマイク増幅器のブロック図である。It is a block diagram of the microphone amplifier of the Example of this invention. 図１のマイク増幅器の動作波形図である。FIG. 2 is an operation waveform diagram of the microphone amplifier of FIG. 1. 従来のマイク増幅器のブロック図である。It is a block diagram of the conventional microphone amplifier. 図３のマイク増幅器の動作波形図である。FIG. 4 is an operation waveform diagram of the microphone amplifier of FIG. 3.

符号の説明Explanation of symbols

１０，１０Ａ：マイク増幅器、１１：入力端子、１２：出力端子、１３：接地端子、１４：増幅回路、１５：ドライバ回路、１６：ダイオード、１７：限流回路、１８：内部電源端子
１：マイクロホン、２：負荷抵抗、３：外部電源端子、４：キャパシタ10, 10A: Microphone amplifier, 11: Input terminal, 12: Output terminal, 13: Ground terminal, 14: Amplifier circuit, 15: Driver circuit, 16: Diode, 17: Current limiting circuit, 18: Internal power supply terminal 1: Microphone 2: Load resistance, 3: External power supply terminal, 4: Capacitor

Claims (2)

マイクロホンに接続される入力端子と、負荷抵抗を介して外部電源端子に接続される出力端子と、接地に接続される接地端子と、前記入力端子に入力する信号を増幅する増幅回路と、該増幅回路の出力信号を入力して前記出力端子を駆動するドライブ回路とを備えたマイク増幅器において、
内部電源端子を設け、該内部電源端子と前記接地との間にキャパシタを接続し、前記内部電源端子を前記増幅回路の電源端子に接続すると共に、前記内部電源端子と前記出力端子との間に限流回路とダイオードの直列回路を接続し、
前記負荷抵抗に流れる前記ドライブ回路の出力電流が前記限流回路とダイオードで検波されてから前記キャパシタで積分され、該キャパシタで得られた電圧が前記増幅回路の電源電圧となるようにしたことを特徴とするマイク増幅器。
An input terminal connected to a microphone, an output terminal connected to an external power supply terminal via a load resistor, a ground terminal connected to ground, an amplifier circuit for amplifying a signal input to the input terminal, and the amplification In a microphone amplifier including a drive circuit that inputs an output signal of a circuit and drives the output terminal,
The internal power supply terminal is provided, connecting the capacitor between the ground and the internal power supply terminal, as well as connecting the internal power supply terminal to the power supply terminal of the amplifier circuit, between the output terminal and the internal power source terminal Connect a series circuit of current limiting circuit and diode,
The output current of the drive circuit flowing through the load resistor is detected by the current limiting circuit and a diode and then integrated by the capacitor, so that the voltage obtained by the capacitor becomes the power supply voltage of the amplifier circuit. Features a microphone amplifier.
請求項１に記載のマイク増幅器において、
前記ダイオードはそのアノードが前記出力端子側となるように接続されていることを特徴とするマイク増幅器。The microphone amplifier according to claim 1, wherein
2. The microphone amplifier according to claim 1, wherein the diode is connected such that an anode thereof is on the output terminal side.
JP2005349881A 2005-12-02 2005-12-02 Microphone amplifier Active JP4741356B2 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR3005823B1 (en) * 2013-05-14 2016-10-14 Elno MICROPHONE COMPRISING A MUTE SWITCH, AND BREATHING MASK COMPRISING SUCH A MICROPHONE

Family Cites Families (10)

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JPS5769912A (en) * 1980-10-21 1982-04-30 Mitsubishi Electric Corp Amplifier for microphone device
JPS6025298A (en) * 1983-07-22 1985-02-08 富士通株式会社 Method of cooling by free access floor
JPS62172803A (en) * 1986-01-27 1987-07-29 Matsushita Electric Works Ltd Plane antenna
JPH03201820A (en) * 1989-12-28 1991-09-03 Sharp Corp Output signal switching circuit
JP3437237B2 (en) * 1994-01-21 2003-08-18 松下電器産業株式会社 Amplifier
JP3701757B2 (en) * 1996-11-19 2005-10-05 株式会社オーディオテクニカ Condenser microphone power circuit
JP3239105B2 (en) * 1998-05-22 2001-12-17 株式会社日立国際電気 Power supply separable amplifier
JP3456193B2 (en) * 2000-06-08 2003-10-14 松下電器産業株式会社 Condenser microphone device
JP2002070375A (en) * 2000-09-05 2002-03-08 Fujitsu Ltd Electronic key and electronic key system
JP2005109842A (en) * 2003-09-30 2005-04-21 Sanyo Electric Co Ltd Amplifier circuit for condenser microphone

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