TWI677185B - 差動放大電路 - Google Patents
差動放大電路 Download PDFInfo
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- TWI677185B TWI677185B TW105140995A TW105140995A TWI677185B TW I677185 B TWI677185 B TW I677185B TW 105140995 A TW105140995 A TW 105140995A TW 105140995 A TW105140995 A TW 105140995A TW I677185 B TWI677185 B TW I677185B
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- H—ELECTRICITY
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- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/02—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
- H03F1/0205—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers
- H03F1/0211—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers with control of the supply voltage or current
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/02—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
- H03F1/0205—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers
- H03F1/0211—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers with control of the supply voltage or current
- H03F1/0216—Continuous control
- H03F1/0222—Continuous control by using a signal derived from the input signal
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/30—Single-ended push-pull [SEPP] amplifiers; Phase-splitters therefor
- H03F3/3001—Single-ended push-pull [SEPP] amplifiers; Phase-splitters therefor with field-effect transistors
- H03F3/3033—NMOS SEPP output stages
- H03F3/3035—NMOS SEPP output stages using differential amplifiers as phase-splitting elements
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/30—Single-ended push-pull [SEPP] amplifiers; Phase-splitters therefor
- H03F3/3001—Single-ended push-pull [SEPP] amplifiers; Phase-splitters therefor with field-effect transistors
- H03F3/3038—PMOS SEPP output stages
- H03F3/304—PMOS SEPP output stages using differential amplifiers as phase-splitting element
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
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- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
- H03F3/45071—Differential amplifiers with semiconductor devices only
- H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
- H03F3/45179—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using MOSFET transistors as the active amplifying circuit
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
- H03F3/45071—Differential amplifiers with semiconductor devices only
- H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
- H03F3/45475—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using IC blocks as the active amplifying circuit
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
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- H03F3/72—Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal
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- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/30—Indexing scheme relating to single-ended push-pull [SEPP]; Phase-splitters therefor
- H03F2203/30087—Only the bias of the pull transistor of the SEPP being dynamically controlled by the input signal
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/30—Indexing scheme relating to single-ended push-pull [SEPP]; Phase-splitters therefor
- H03F2203/30099—Indexing scheme relating to single-ended push-pull [SEPP]; Phase-splitters therefor the pull transistor being gated by a switching element
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
- H03F3/45071—Differential amplifiers with semiconductor devices only
- H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
- H03F3/45179—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using MOSFET transistors as the active amplifying circuit
- H03F3/45183—Long tailed pairs
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Abstract
本發明提供一種消耗電流低且電路面積小的差動放大電路。本發明的差動放大電路具有與二級放大電路串聯連接的二級輸出電晶體,且藉由第1級放大電路的輸出來進行對二個輸出電晶體中的其中一個的控制,並將另一個輸出電晶體構成以第2級放大電路的輸出來控制的汲極接地電路(源極隨耦電路)。
Description
本發明是有關於一種對二個輸入電壓的差進行放大的差動放大電路。
差動放大電路被廣泛用於各種電子設備中。尤其,藉由施加負回饋,可實現高精度的類比(analog)信號處理,對於當今的電子設備的發展而言是不可或缺的技術。 差動放大電路的功能在於對二個輸入電壓的差進行放大,但以電池驅動的行動(mobile)電子設備為代表,一直要求低消耗電流化與小型輕量化。
圖3表示習知的差動放大電路。習知的差動放大電路包含:第1級放大電路1,對二個輸入端子IP及輸入端子IN的電壓差進行放大;第2級放大電路2及第2級放大電路6,對放大電路1的輸出端子OP及輸出端子ON的電壓差進行放大;P型金屬氧化物半導體(Metal Oxide Semiconductor,MOS)電晶體(transistor)即輸出電晶體7,藉由放大電路2的輸出GH而閘極(gate)受到控制;以及N型MOS電晶體即輸出電晶體3,藉由放大電路6的輸出GL而受到控制。
如上所述的差動放大電路藉由設置輸出電晶體3及輸出電晶體7而實現輸出端子OUT的低阻抗(impedance),藉由設置第2級放大電路2及第2級放大電路6,從而使輸出電晶體3及輸出電晶體7進行動作的偏壓設定變得容易。 現有技術文獻 專利文獻
專利文獻1:日本專利特開平03-274911號公報
[發明所欲解決之問題] 然而,所述差動放大電路具備三個放大電路,因此存在消耗電流多,電路面積大的缺點。
本發明是為了解決如上所述的問題而創作,實現一種消耗電流低且電路面積小的差動放大電路。 [解決問題之手段]
為了解決現有的問題,本發明的差動放大電路採用如下所述的構成。 本發明的差動放大電路具有與二級放大電路串聯連接的二級輸出電晶體,且藉由第1級放大電路的輸出來進行對二個輸出電晶體中的其中一個的控制,並將另一個輸出電晶體構成為利用第2級放大電路的輸出來控制的汲極(drain)接地電路(源極隨耦(source follower)電路)。 [發明的效果]
根據本發明的差動放大電路,藉由第1級放大電路的輸出來進行對二個輸出電晶體中的其中一個的控制,藉此,具有下述效果:可削減一個放大電路,從而可削減消耗電流與電路面積而不會有損低輸出阻抗與輸出電晶體進行動作的偏壓設定的容易性。
進而,藉由將利用第2級放大電路的輸出來控制的輸出電晶體設為汲極接地電路,從而具有下述效果:可抑制電壓放大增益,並可削減在對放大電路施加負回饋來使用時所需的相位補償電路。
圖1是本實施形態的差動放大電路的電路圖。 本實施形態的差動放大電路具備放大電路1、放大電路2與N型MOS電晶體即輸出電晶體3及輸出電晶體4。
放大電路1的二個輸入端子連接差動放大電路的輸入端子IP及輸入端子IN,將對二個輸入端子的電壓差進行放大所得的電壓作為輸出端子OP與輸出端子ON的電壓差而輸出。放大電路2的二個輸入端子連接放大電路1的輸出端子OP及輸出端子ON,將對輸出端子OP與輸出端子ON的電壓差進行放大所得的電壓輸出至輸出端子GH。輸出電晶體3的閘極連接放大電路1的輸出端子ON,源極連接於接地(ground),汲極連接於輸出端子OUT。輸出電晶體4的閘極連接有放大電路2的輸出端子GH,汲極連接於電源端子,源極連接於輸出端子OUT。 所述圖1的電路構成了將對輸入端子IP及輸入端子IN的電壓差進行放大所得的電壓輸出至輸出端子OUT的差動放大電路。
接下來,對本實施形態的差動放大電路的動作進行說明。 在差動放大電路的輸入端子IP與輸入端子IN的電壓差為正的情況下,放大電路1的輸出端子OP與輸出端子ON的電位差也為正,輸出端子OP的電壓接近電源電壓,輸出端子ON的電壓接近接地電壓。並且,輸出電晶體3由於閘極電壓變小,因此電流驅動能力變小。在輸出端子OP與輸出端子ON的電位差為正的情況下,放大電路2的輸出端子GH的電壓接近電源電壓。並且,輸出電晶體4由於閘極電壓變大,因此電流驅動能力變大。因而,差動放大電路向輸出端子OUT輸出與輸入端子IP和輸入端子IN的電壓差相應的高電壓。
在差動放大電路的輸入端子IP與輸入端子IN的電壓差為負的情況下,放大電路1的輸出端子OP與輸出端子ON的電位差也為負,輸出端子OP的電壓接近接地電壓,輸出端子ON的電壓接近電源電壓。並且,輸出電晶體3由於閘極電壓變大,因此電流驅動能力變大。在輸出端子OP與輸出端子ON的電位差為負的情況下,放大電路2的輸出端子GH的電壓接近接地電壓。並且,輸出電晶體4由於閘極電壓變小,因此電流驅動能力變小。因而,差動放大電路向輸出端子OUT輸出與輸入端子IP和輸入端子IN的電壓差相應的低電壓。
此處,放大電路1的輸出端子OP與輸出端子ON的電壓差相對於輸入端子IP與輸入端子IN的電壓差而為放大電路1的差動增益倍。而且,輸出端子ON的電壓變化相對於輸入端子IP與輸入端子IN的電壓差而為放大電路1的單相增益倍。放大電路2的輸出端子GH的電壓變化相對於放大電路1的輸出端子OP與輸出端子ON的電壓差而為放大電路2的增益倍。進而,輸出電晶體3構成源極接地放大電路,具備對放大電路1的輸出端子ON的電壓變化的放大作用。 另外,放大電路1的輸出端子OP與輸出端子ON的電壓的變化量的絕對值未必需要相等,輸出端子OP的電壓變化量亦可為零。
如以上所說明般,圖1的電路作為將對輸入端子IP與輸入端子IN的電壓差進行放大所得的電壓輸出至輸出端子OUT的差動放大電路發揮功能。 如上所述,本實施形態的差動放大電路採用了將輸出電晶體3的閘極連接於放大電路1的輸出端子ON的構成,因此可削減一個放大電路,與習知技術相比較,可削減消耗電流與電路面積。
進而,由於將閘極連接放大電路2的輸出端子GH的輸出電晶體4設為汲極接地電路,抑制了輸出電晶體4的增益,因此與習知技術相比較,可削減對差動放大電路施加負回饋來使用時所需的相位補償電路。另外,負回饋電路或相位補償電路已為本領域技術人員普遍廣泛知曉,因而未作圖示。
圖2是表示本實施形態的差動放大電路的另一例的電路圖。圖2的差動放大電路相對於圖1的差動放大電路而新具備PMOS電晶體5。 PMOS電晶體5的閘極連接有控制信號端子ENB,源極連接於電源端子,汲極連接於輸出電晶體4的汲極。 PMOS電晶體5作為開關發揮功能,所述開關在控制信號端子ENB為接地電壓時成為導通(ON)狀態而在控制信號端子ENB為電源電壓時成為斷開(OFF)狀態。
差動放大電路在放大電路2的輸出端子GH成為接地電壓,輸出電晶體4為斷開狀態的情況下,有時會有被稱作斷開漏(off leak)電流的漏電流流至輸出電晶體4。此在為了使輸出端子OUT的輸出電壓更接近電源電壓而降低輸出電晶體4的閾值電壓的情況下變得更為顯著。
本實施形態的差動放大電路中,在有漏電流流至輸出電晶體4的狀況下,可藉由將控制信號ENB作為電源電壓且將PMOS電晶體5設為斷開狀態來抑制漏電流。 另外,通常,對於PMOS電晶體5的尺寸,容易將尺寸設定為:在導通狀態下,導通電阻充分小,而在斷開狀態下,漏電流充分小。
如以上所說明般,本實施形態的差動放大電路採用了將輸出電晶體4經由作為開關發揮功能的PMOS電晶體5而與電源端子連接的構成,因此可抑制輸出電晶體4為斷開狀態時的漏電流,從而可削減消耗電流。
另外,明確的是:在本實施形態的差動放大電路中,將輸出電晶體4作為PMOS電晶體而與放大電路1的輸出連接,將輸出電晶體3作為PMOS電晶體而與放大電路2的輸出連接,且將作為開關發揮功能的電晶體5作為NMOS電晶體而設置於輸出電晶體3與接地之間,亦可獲得同樣的效果。
1、2、6‧‧‧放大電路
3、4‧‧‧N型MOS電晶體
5、7‧‧‧P型MOS電晶體
ENB‧‧‧控制信號端子
GH、ON、OP、OUT‧‧‧輸出端子
GL‧‧‧輸出
IP、IN‧‧‧輸入端子
圖1是本實施形態的差動放大電路的電路圖。 圖2是表示本實施形態的差動放大電路的另一例的電路圖。 圖3是現有的差動放大電路的電路圖。
Claims (2)
- 一種差動放大電路,對第1輸入電壓與第2輸入電壓的差進行放大,所述差動放大電路的特徵在於包括: 第1放大電路,對所述第1輸入電壓及第2輸入電壓的差進行放大,並作為第1輸出電壓與第2輸出電壓之差而輸出; 第2放大電路,對所述第1放大電路的輸出電壓之差進一步進行放大;以及 串聯連接的第1輸出電晶體與第2輸出電晶體, 其中所述第1輸出電晶體的閘極輸入所述第1輸出電壓,所述第1輸出電晶體的源極連接於第2電源端子,所述第1輸出電晶體的汲極連接於輸出端子, 其中所述第2輸出電晶體的閘極輸入所述第2放大電路的輸出電壓,所述第2輸出電晶體的源極連接於所述輸出端子,所述第2輸出電晶體的汲極連接於第1電源端子。
- 如申請專利範圍第1項所述的差動放大電路,其中 所述第2輸出電晶體的汲極經由作為開關發揮功能的電晶體而連接於所述第1電源端子。
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JP2015252370A JP6571518B2 (ja) | 2015-12-24 | 2015-12-24 | 差動増幅回路 |
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2015
- 2015-12-24 JP JP2015252370A patent/JP6571518B2/ja active Active
-
2016
- 2016-12-12 TW TW105140995A patent/TWI677185B/zh active
- 2016-12-20 US US15/385,116 patent/US9979351B2/en active Active
- 2016-12-23 CN CN201611205248.7A patent/CN107026624A/zh active Pending
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5285168A (en) * | 1991-09-18 | 1994-02-08 | Hitachi, Ltd. | Operational amplifier for stably driving a low impedance load of low power consumption |
US8310306B2 (en) * | 2009-06-09 | 2012-11-13 | Fujitsu Semiconductor Limited | Operational amplifier |
Also Published As
Publication number | Publication date |
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JP2017118351A (ja) | 2017-06-29 |
TW201725851A (zh) | 2017-07-16 |
US20170187330A1 (en) | 2017-06-29 |
JP6571518B2 (ja) | 2019-09-04 |
CN107026624A (zh) | 2017-08-08 |
US9979351B2 (en) | 2018-05-22 |
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