JP6686259B2 - Microphone amplifier - Google Patents

Microphone amplifier Download PDF

Info

Publication number
JP6686259B2
JP6686259B2 JP2015228712A JP2015228712A JP6686259B2 JP 6686259 B2 JP6686259 B2 JP 6686259B2 JP 2015228712 A JP2015228712 A JP 2015228712A JP 2015228712 A JP2015228712 A JP 2015228712A JP 6686259 B2 JP6686259 B2 JP 6686259B2
Authority
JP
Japan
Prior art keywords
parallel connection
amplifier
connection diode
microphone
input terminal
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.)
Active
Application number
JP2015228712A
Other languages
Japanese (ja)
Other versions
JP2017098744A (en
Inventor
竜平 根本
竜平 根本
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.)
New Japan Radio Co Ltd
Original Assignee
New Japan Radio 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 New Japan Radio Co Ltd filed Critical New Japan Radio Co Ltd
Priority to JP2015228712A priority Critical patent/JP6686259B2/en
Publication of JP2017098744A publication Critical patent/JP2017098744A/en
Application granted granted Critical
Publication of JP6686259B2 publication Critical patent/JP6686259B2/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Landscapes

  • Circuit For Audible Band Transducer (AREA)
  • Amplifiers (AREA)

Description

本発明は、コンデンサマイクロホンと増幅器を備えたマイクロホン増幅装置に関する。   The present invention relates to a microphone amplification device including a condenser microphone and an amplifier.

図３に従来のマイクロホン増幅装置を示す。１０はコンデンサマイクロホン、２０は増幅器である。増幅器２０はコンデンサマイクロホン１０で発生した音声信号を増幅する。７０はＥＳＤ（Electro-Static Discharge：静電気放電）保護用に２個のダイオードを逆並列接続して構成した逆並列接続ダイオードである。このような逆並列接続ダイオードをＥＳＤ保護用に使用するマイクロホン増幅装置として、特許文献１、２に記載がある。   FIG. 3 shows a conventional microphone amplifier. Reference numeral 10 is a condenser microphone, and 20 is an amplifier. The amplifier 20 amplifies the audio signal generated by the condenser microphone 10. Reference numeral 70 denotes an anti-parallel connection diode constituted by connecting two diodes in anti-parallel for ESD (Electro-Static Discharge) protection. Patent Documents 1 and 2 describe a microphone amplifying device using such an anti-parallel connection diode for ESD protection.

この逆並列接続ダイオード７０は、ＥＳＤ保護機能の他に、増幅器２０の入力端子２１を高抵抗にして増幅器２０にバイアスを与える働きをしている。抵抗ではなく逆並列接続ダイオード７０を使用する理由は、電源投入直後に比較的短時間で増幅器２０の入力端子２１のバイアスを安定化できること、全体を半導体装置で構成する場合に逆並列接続ダイオード７０の面積が小さくて済むことである。   The anti-parallel connection diode 70 has a function of making the input terminal 21 of the amplifier 20 a high resistance and biasing the amplifier 20 in addition to the ESD protection function. The reason why the anti-parallel connection diode 70 is used instead of the resistor is that the bias of the input terminal 21 of the amplifier 20 can be stabilized in a relatively short time immediately after the power is turned on. The area is small.

ところで、マイクロホン増幅装置のノイズ成分は、増幅器２０自体で発生するノイズと逆並列接続ダイオード７０で発生するノイズの和となる。逆並列接続ダイオード７０で発生するノイズは、図４に示す電流／電圧特性図の０Ｖ付近のダイオード抵抗に依存し、その抵抗値が大きいほどノイズが大きくなる。   By the way, the noise component of the microphone amplifier is the sum of the noise generated by the amplifier 20 itself and the noise generated by the anti-parallel connection diode 70. The noise generated in the anti-parallel connection diode 70 depends on the diode resistance near 0 V in the current / voltage characteristic diagram shown in FIG. 4, and the noise increases as the resistance value increases.

逆並列接続ダイオード７０の抵抗値が大きくなると、その抵抗成分とコンデンサマイクロホン１０の持っているキャパシタ成分とで構成されるフィルタのカットオフ周波数が低下するので、音声帯域のノイズを抑制して小さくすることができる。   When the resistance value of the anti-parallel connection diode 70 increases, the cutoff frequency of the filter formed by the resistance component and the capacitor component of the condenser microphone 10 decreases, so that noise in the voice band is suppressed and reduced. be able to.

特開昭５７−５２１７５号公報JP-A-57-52175 特開２０１１−２３３９５４号公報JP, 2011-233954, A

そこで、増幅器２０の入力抵抗を大きくするために逆並列接続ダイオード７０のサイズを小さくすることが考えられるが、そのようにすると、ＥＳＤ耐量が低下してしまい破壊し易くなるという問題があった。   Therefore, it is conceivable to reduce the size of the anti-parallel connection diode 70 in order to increase the input resistance of the amplifier 20, but doing so causes a problem that the ESD withstand level decreases and the diode is easily destroyed.

本発明の目的は、ＥＳＤ耐量の低下を防止しながら増幅器の入力抵抗を大きくできるようにしたマイクロホン増幅装置を提供することである。   An object of the present invention is to provide a microphone amplifying device capable of increasing the input resistance of an amplifier while preventing a decrease in ESD tolerance.

上記目的を達成するために、請求項１にかかる発明は、コンデンサマイクロホンと、該コンデンサマイクロホンで発生する音声信号を増幅する増幅器と、該増幅器の入力端子と接地との間に接続される第１の逆並列接続ダイオードと、を備えるマイクロホン増幅装置において、前記第１の逆並列接続ダイオードに第１の抵抗を直列接続し、且つ前記増幅器の前記入力端子と前記接地との間に第２の逆並列接続ダイオードを２以上直列接続し、前記第１の抵抗によって、前記入力端子と前記接地との間の抵抗値を前記第１の逆並列接続ダイオードの抵抗値よりも大きくし、２以上の前記第２の逆並列接続ダイオードによって、前記入力端子と前記接地との間のＥＳＤ耐量を前記第１の逆並列接続ダイオードのＥＳＤ耐量よりも大きくしたことを特徴とする。
In order to achieve the above-mentioned object, the invention according to claim 1 is characterized in that a condenser microphone, an amplifier for amplifying an audio signal generated by the condenser microphone, and a first connection connected between an input terminal of the amplifier and ground. An anti-parallel connection diode according to claim 1, wherein a first resistor is connected in series to the first anti-parallel connection diode, and a second inverse connection is provided between the input terminal of the amplifier and the ground. Two or more parallel-connected diodes are connected in series , and the resistance value between the input terminal and the ground is made larger than the resistance value of the first anti-parallel connection diode by the first resistance, and the two or more of the two are connected. the second inverse parallel connection diodes, that the ESD immunity between the ground and the input terminal is larger than the ESD tolerance of the first inverse-parallel connected diodes And butterflies.

請求項２にかかる発明は、請求項１に記載のマイクロホン増幅装置において、前記第２の逆並列接続ダイオードは、前記第１の逆並列接続ダイオードよりもサイズが大きく設定されていることを特徴とする。   According to a second aspect of the present invention, in the microphone amplifying device according to the first aspect, the size of the second anti-parallel connection diode is set larger than that of the first anti-parallel connection diode. To do.

本発明によれば、第１の逆並列接続ダイオードと第１の抵抗によって増幅器の入力抵抗を大きくし、２個以上並列接続した第２の逆並列接続ダイオードによってＥＳＤ耐量の低下を防止することができる。   According to the present invention, the input resistance of the amplifier can be increased by the first anti-parallel connection diode and the first resistance, and the decrease of the ESD withstand capability can be prevented by the second anti-parallel connection diode in which two or more are connected in parallel. it can.

本発明の１つの実施例のマイクロホン増幅装置の回路図である。1 is a circuit diagram of a microphone amplification device according to one embodiment of the present invention. 図１のマイクロホン増幅装置の増幅器の入力端子の電圧／電流特性図である。FIG. 2 is a voltage / current characteristic diagram of an input terminal of an amplifier of the microphone amplification device of FIG. 1. 従来のマイクロホン増幅装置の回路図である。It is a circuit diagram of the conventional microphone amplifier. 図３のマイクロホン増幅装置の増幅器の入力端子の電圧／電流特性図である。FIG. 4 is a voltage / current characteristic diagram of an input terminal of an amplifier of the microphone amplification device of FIG. 3.

図１に本発明の１つの実施例のマイクロホン増幅装置を示す。図３で説明したものと同じものには同じ符号をつけた。本実施例では、増幅器２０の入力端子２１と接地ＧＮＤとの間に、逆並列接続ダイオード３０に抵抗４０を直列接続した直列回路を接続している。さらに、増幅器２０の入力端子２１と接地ＧＮＤとの間に、逆並列接続ダイオード５０，６０を直列接続した直列回路を接続している。   FIG. 1 shows a microphone amplifying device according to one embodiment of the present invention. The same components as those described in FIG. 3 are designated by the same reference numerals. In this embodiment, a series circuit in which a resistor 40 is connected in series to an antiparallel connection diode 30 is connected between the input terminal 21 of the amplifier 20 and the ground GND. Further, a series circuit in which antiparallel connection diodes 50 and 60 are connected in series is connected between the input terminal 21 of the amplifier 20 and the ground GND.

逆並列接続ダイオード３０はサイズが小さく、図３で説明した逆並列接続ダイオード７０よりも高抵抗であり、図２のＡにその電流／電圧特性を示す。この逆並列接続ダイオード３０は抵抗４０と直列接続されており、増幅器２０の入力端子２１の電圧が高くなったときに、そこに流れる電流を抑制する。図２のＢに抵抗４０の電流／電圧特性を示す。   The anti-parallel connection diode 30 has a small size and has a higher resistance than the anti-parallel connection diode 70 described in FIG. 3, and its current / voltage characteristic is shown in A of FIG. The anti-parallel connection diode 30 is connected in series with the resistor 40, and suppresses the current flowing therethrough when the voltage of the input terminal 21 of the amplifier 20 becomes high. FIG. 2B shows the current / voltage characteristic of the resistor 40.

逆並列接続ダイオード５０，６０は逆並列接続ダイオード３０よりもサイズが大きく、単体の抵抗値は逆並列接続ダイオード３０よりも小さいが、直列接続することでオン電圧を高くし合計抵抗を大きくしている。図２のＣにその電流／電圧特性を示す。   The anti-parallel connection diodes 50 and 60 are larger in size than the anti-parallel connection diode 30 and have a single resistance value smaller than that of the anti-parallel connection diode 30. However, by connecting them in series, the ON voltage is increased and the total resistance is increased. There is. The current / voltage characteristic is shown in C of FIG.

図２のＤは、以上説明した電流／電圧特性Ａ，Ｂ，Ｃを合成した電流／電圧特性である。この特性で明らかなように、増幅器２０の入力端子２１と接地ＧＮＤとの間には、高抵抗で高いＥＳＤ耐量を備えた回路が接続されることになり、ＥＳＤ耐量を大きくしながら増幅器の入力抵抗を大きくすることができる。   D in FIG. 2 is a current / voltage characteristic obtained by combining the current / voltage characteristics A, B, and C described above. As is clear from this characteristic, a circuit having a high resistance and a high ESD resistance is connected between the input terminal 21 of the amplifier 20 and the ground GND, and the input of the amplifier is increased while increasing the ESD resistance. The resistance can be increased.

つまり、逆並列接続ダイオード３０と抵抗４０によって増幅器２０の入力端子２１の抵抗を大きくし、逆並列接続ダイオード５０，６０によってＥＳＤ耐量を大きくすることができる。   That is, the resistance of the input terminal 21 of the amplifier 20 can be increased by the anti-parallel connection diode 30 and the resistor 40, and the ESD tolerance can be increased by the anti-parallel connection diodes 50 and 60.

なお、逆並列接続ダイオード３０と抵抗４０の接続順は逆であってもよい。また、上記では２個の逆並列接続ダイオード５０，６０を直列接続したが、直列接続する逆並列接続ダイオードは３個以上であってもよい。   The reverse parallel connection diode 30 and the resistor 40 may be connected in reverse order. Further, although the two anti-parallel connection diodes 50 and 60 are connected in series in the above, the number of anti-parallel connection diodes connected in series may be three or more.

１０：コンデンサマイクロホン
２０：増幅器、２１：入力端子
３０，５０，６０，７０：逆並列接続ダイオード
４０：抵抗 10: condenser microphone 20: amplifier, 21: input terminal 30, 50, 60, 70: anti-parallel connection diode 40: resistor

Claims (2)

コンデンサマイクロホンと、該コンデンサマイクロホンで発生する音声信号を増幅する増幅器と、該増幅器の入力端子と接地との間に接続される第１の逆並列接続ダイオードと、を備えるマイクロホン増幅装置において、
前記第１の逆並列接続ダイオードに第１の抵抗を直列接続し、且つ前記増幅器の前記入力端子と前記接地との間に第２の逆並列接続ダイオードを２以上直列接続し、
前記第１の抵抗によって、前記入力端子と前記接地との間の抵抗値を前記第１の逆並列接続ダイオードの抵抗値よりも大きくし、２以上の前記第２の逆並列接続ダイオードによって、前記入力端子と前記接地との間のＥＳＤ耐量を前記第１の逆並列接続ダイオードのＥＳＤ耐量よりも大きくしたことを特徴とするマイクロホン増幅装置。
A microphone amplifying device comprising a condenser microphone, an amplifier for amplifying an audio signal generated by the condenser microphone, and a first anti-parallel connection diode connected between an input terminal of the amplifier and the ground,
A first resistor is connected in series with the first anti-parallel connection diode, and two or more second anti-parallel connection diodes are connected in series between the input terminal of the amplifier and the ground ;
A resistance value between the input terminal and the ground is made larger than a resistance value of the first anti-parallel connection diode by the first resistor, and two or more second anti-parallel connection diodes are provided by the second anti-parallel connection diode. A microphone amplifying device , wherein an ESD tolerance between an input terminal and the ground is set larger than an ESD tolerance of the first anti-parallel connection diode .
請求項１に記載のマイクロホン増幅装置において、
前記第２の逆並列接続ダイオードは、前記第１の逆並列接続ダイオードよりもサイズが大きく設定されていることを特徴とするマイクロホン増幅装置。 The microphone amplification device according to claim 1, wherein
The microphone amplification device, wherein the second anti-parallel connection diode is set to have a size larger than that of the first anti-parallel connection diode.
JP2015228712A 2015-11-24 2015-11-24 Microphone amplifier Active JP6686259B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2015228712A JP6686259B2 (en) 2015-11-24 2015-11-24 Microphone amplifier

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2015228712A JP6686259B2 (en) 2015-11-24 2015-11-24 Microphone amplifier

Publications (2)

Publication Number Publication Date
JP2017098744A JP2017098744A (en) 2017-06-01
JP6686259B2 true JP6686259B2 (en) 2020-04-22

Family

ID=58803874

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2015228712A Active JP6686259B2 (en) 2015-11-24 2015-11-24 Microphone amplifier

Country Status (1)

Country Link
JP (1) JP6686259B2 (en)

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4252511B2 (en) * 2004-07-30 2009-04-08 新日本無線株式会社 Semiconductor device
US20130129117A1 (en) * 2011-11-21 2013-05-23 Henrik Thomsen Audio amplification circuit

Also Published As

Publication number Publication date
JP2017098744A (en) 2017-06-01

Similar Documents

Publication Publication Date Title
JP6341461B2 (en) Power amplifier
US7719363B2 (en) Method and apparatus for output amplifier protection
US20110043279A1 (en) Electronic volume circuit
JP2008514183A (en) Peak voltage protection circuit and method
TW201448454A (en) Radio frequency power amplifier and electronic system
JP2016167516A (en) Electrostatic protection circuit
JP6410007B2 (en) Cascode amplifier
JP2009225100A (en) Semiconductor integrated circuit and capacitor microphone
JP2011109642A (en) Initial-stage amplifier circuit and electronic apparatus employing the same
JP2009087962A (en) Protection circuit and semiconductor integrated circuit
TWI595801B (en) Optical module
JP6686259B2 (en) Microphone amplifier
CN112042115B (en) Amplifying circuit
US9692362B2 (en) Amplifier circuit applied to display apparatus
JP6330364B2 (en) Amplifier circuit protection circuit
JP5970241B2 (en) Capacitive load bias circuit
JP2011155062A (en) Semiconductor device
JP6379476B2 (en) Semiconductor device
JP2006115255A (en) Operational amplifier
US7830206B2 (en) Amplifier circuit
JP2008288236A (en) Semiconductor integrated circuit
JP2013201164A (en) Semiconductor device
US9236839B2 (en) Class-G amplifier and audio system employing the amplifier
KR102016488B1 (en) Power amplifier
JP4542424B2 (en) Static electricity countermeasure circuit and amplifier device

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20181002

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20190816

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20190902

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20191009

RD05 Notification of revocation of power of attorney

Free format text: JAPANESE INTERMEDIATE CODE: A7425

Effective date: 20200207

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20200303

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20200309

R150 Certificate of patent or registration of utility model

Ref document number: 6686259

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R150

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250