CN1103519A - Electric signal amplifier - Google Patents

Electric signal amplifier Download PDF

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Publication number
CN1103519A
CN1103519A CN 94111130 CN94111130A CN1103519A CN 1103519 A CN1103519 A CN 1103519A CN 94111130 CN94111130 CN 94111130 CN 94111130 A CN94111130 A CN 94111130A CN 1103519 A CN1103519 A CN 1103519A
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resistance
effect transistor
field effect
amplifier
triode
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高林
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Abstract

The electric signal amplifier, especially audio signal amplifier features that the emitter of transistor or source of FET is used as output to basic output control network and a float ground technique is used, which is characterized by separating output signal ground from input one to form a potential difference. The amplifier has better static and dynamic specifications, so omiting negative feedback.

Description

Electric signal amplifier
The invention belongs to signal of telecommunication basic amplifier circuit unit, be particularly suitable in the amplification of acoustic product and other analog electrical signal, using.
Common electron-amplifier, audio signal amplifier particularly, owing to be subjected to active device (as electron tube, bipolar transistor, field effect transistor etc.) effect of nonlinear, obtain low harmonic distortion, static index such as good frequency characteristic, must apply the loop negative feedback, like this, though improved static index, but the dynamic indicator that makes amplifier becomes bad, for a given amplifying circuit, deepens the negative and feedback of loop and makes that static index is good more, dynamic indicator is just poor more, can not solve this well, can only adopt compromise way contradiction.Base amplifier can not fully phase out the degenerative reason of loop, is that if do not add the loop negative feedback, its distortion factor will arrive outrageous degree greatly because the single-stage distortion of each unit amplifying circuit of these amplifiers of formation is big.Want to fully phase out the loop negative feedback, must make each the unit amplifying circuit that constitutes amplifier have very low distortion.Three kinds of basic configurations at amplifying device, be cobasis (grid), cascode (source), collect in (leakage) polar circuit altogether, to collect (leakage) polar circuit altogether, the performance of penetrating (source) utmost point follower that is common indication is best, but it has only the electric current amplification and the no-voltage amplification, therefore only makes impedance conversion and output stage usually and uses.
The objective of the invention is to design a class and both had the superior function of penetrating (source) utmost point follower, the electric signal amplifier that has electric current and voltage amplification ability again, with cancellation loop negative feedback, obtain than the static index of existing base amplifier and dynamic indicator all superior the electric signal amplifier of Duoing.
Purpose of the present invention realizes by following major technique approach: triode or field effect transistor are connected into penetrate (source) utmost point output form, design a special basic output Control Network, adopt floating ground structure, specifically technical scheme is as follows:
Scheme 1, a kind of electric signal amplifier of forming by single triode or field effect transistor, its triode BG 1Emitter or the source electrode of field effect transistor be connected to one by resistance R e 1, Re 2, Re 3With load resistance R LThe basic output Control Network of forming, wherein resistance R e 2, Re 3And R LConstitute a △ l network, this △ l network and resistance R e 1Series connection, Re 1Simultaneously with triode BG 1Emitter or the source electrode of field effect transistor join input signal u iEarth point be connected on resistance R e 3An end, power supply+E 2With output signal u oBe attempted by resistance R e altogether 3The other end.
Scheme 2, structure and scheme 1 are basic identical, and its difference is that mainly its biasing circuit meets another bias supply+E 1, bias supply+E 1With input signal u iBe attempted by resistance R e altogether 3An end.
Scheme 3, this is a kind of complementary push-pull type electric signal amplifier of being made up of two triodes or field effect transistor, two triode BG 2, BG 3Emitter or the source electrode of field effect transistor connect one with scheme 1 in the identical output Control Network of basic output Control Network structure, its biasing circuit can have bias supply+E 1Or ± E 1, bias supply+E 1Or ± E 1With input signal u iBe attempted by resistance R e altogether 3An end, amplifier tube out-put supply+E 2Or ± E 2With output signal u oBe attempted by resistance R e altogether 3The other end.
Scheme 4, this is a kind of four pipe cross-couplings type electric signal amplifiers of being made up of four triodes or field effect transistor, two triodes of its output or field effect transistor BG 6, BG 7Emitter or source electrode on be connected to one with scheme 1 in the identical output Control Network of basic output Control Network structure, its coupling triode or field effect transistor BG 4, BG 5Can have bias supply+E 1Or ± E 1, bias supply+E 1Or ± E 1With input signal u iBe attempted by resistance R e altogether 3An end, out-put supply+E 2Or ± E 2With output signal u oBe attempted by resistance R e altogether 3The other end.
The present invention through adopting analytical calculation of small-signal equivalent circuit method and actual test and using, proves that it has following advantage owing to adopt as above technical scheme:
1, adopt this class element circuit to pass through cascade system, can constitute amplifier completely without loop feedback, when doing the audio frequency amplifier use, can accomplish completely without the loop feedback structure that present stage, all amplification modes were not accomplished from equalizer amplifier, preamplifier, power amplifier under the situation that keeps same static index.Cancelled loop feedback, there is not the problem of self-excitation in amplifier, does not need weakening, makes the frequency band of amplifier and associated switching rate considerably beyond the amplifier of present stage, and the ability of amplifier reproducing signal waveform is significantly improved.
2, generally speaking, amplify and output by finishing with one-level, make amplifier-chain than present stage other amplifier more succinct.When making up with the existing conventional amplifier, can apply the loop negative feedback, even if like this, the amplifier of composition is keeping under the gain situation identical with other index, circuit is also more succinct, and can provide three kinds of different type of drive to load.
3, can adopt the method for ride gain to realize volume control, indexs such as signal to noise ratio, the distortion factor, dynamic range substantially exceed the conventional method that adopts decay input signal control volume when making small volume, with the Gm technology of JVC play the same tune on different musical instruments wonderful are arranged.
4, can be compatible with present acoustic product.
Description of drawings:
Fig. 1 is a single tube single supply amplifier electrical schematic diagram.
Fig. 2 is a single tube duplicate supply amplifier electrical schematic diagram.
Fig. 3 is the small-signal equivalent circuit figure of single tube duplicate supply amplifier.
Fig. 4 is the double tube complementation push-pull amplifier electrical schematic diagram that adopts positive-negative power.
Fig. 5 is the four pipe cross coupled amplifier electrical schematic diagrams that adopt positive-negative power.
Fig. 6 is embodiment 1 electrical schematic diagram.
Fig. 7 is embodiment 2 electrical schematic diagrams.
Fig. 8 is embodiment 3 electrical schematic diagrams.
Fig. 9 is embodiment 4 electrical schematic diagrams.
Below in conjunction with accompanying drawing and embodiment the present invention is done detailed description:
The present invention includes following four basic schemes based on same technical conceive:
Scheme 1, as shown in Figure 1, this is a kind of electric signal amplifier of being made up of single triode or field effect transistor, its triode BG 1Emitter or the source electrode of field effect transistor be connected to one by resistance R e 1, Re 2, Re 3With load resistance R LThe basic output Control Network of forming, wherein resistance R e 2, Re 3, R LConstitute a △ l network, this △ l network and resistance R e 1Series connection, Re 1Simultaneously with triode BG 1Emitter or the source electrode of field effect transistor join input signal u iEarth point be connected on resistance R e 3An end, power supply+E 2With output signal u oBe attempted by resistance R e altogether 3The other end.
On its input circuit and output loop, meet a capacitance C respectively iAnd C o
Scheme 2, as shown in Figure 2, its structure and scheme 1 are basic identical, and its difference mainly is to be connected to one bias supply+E on its biasing circuit 1(in order to improve input impedance, the back is together), power supply+E 1With input signal u iBe attempted by resistance R e altogether 3An end.
Below the amplification principle of scheme 2 is analyzed:
Fig. 3 is its small-signal equivalent circuit figure, according to Fig. 3, has for input circuit:
u i=i bR Be+ (1+ β) i bRe 1+ ie 2Re 21. have for output loop:
u o＝i o·R L＝[（1+β）·i b-ie 2]·R L……②
u o＝ie 2·Re 2+（ie 2-i b）Re 3
＝ie 2（Re 2+Re 3）-i b·Re 3……③
Can get by above equation group:
u i＝ (R L+Re 2+Re 3)/(R L·[(1+β)·Re 2+β·Re 3]) ·[r be+（1+β）·Re 1]·u o+｛（1+β）· (R L+Re 2+Re 3)/(R L·[(1+β)·Re 2+β·Re 3]) ·u o- (u o)/(R L) ｝·Re 2
When β＞＞1, (1+ β) available β replaces r Bc＜＜(1+ β) Re 1, [r Be+ (1+ β) Re 1] available β Re 1Replace, following formula simplified and can be got:
u i＝ (R L(Re 1+Re 2)+Re 1(Re 2+Re 3))/(R L(Re 2+Re 3)) ·u o……④
So:
K V = u o u i = 1 R e 1 R L + R e 1 +R e 2 R e 2 +R e 3
In following formula, be easy to satisfy K vAs long as＞1 condition is for example R L＞2Re 1And Re 3＞2Re 1+ Re 2Set up simultaneously, promptly have:
K v＞1
Thereby confirm that it has the voltage amplification effect.
Calculate its floating earthy potential difference below again:
So-called floating earthy potential difference is meant the alternating component of difference of the earth potential of the earth potential of output signal and input signal.
U Re3＝u o-ie 2·Re 2
By 1., 2., 3. Shi Kede:
ie 2＝（1+β） (R L+Re 2+Re 3)/(R L[(1+β)Re 2+βRe 3]) ·u o- (u O)/(R L)
Thereby have:
U Re3＝U o-
{ ((1+β)R L+(1+β)Re 2+(1+β)Re 3-(1+β)Re 2-βRe 3)/(R L·[(1+β)Re 2+βRe 3]) }·u o·Re 2
When β＞＞1, (1+ β) available β replaces, and can get after following formula is simplified:
U Re3＝ (Re 3·R L)/(R L(Re 1+Re 2)+Re 1(Re 2+Re 3)) ·u i
Being that its floating earth potential changes by above-mentioned rule with input signal, is the key that amplifying circuit involved in the present invention is realized amplification.
Analyze the output characteristic under the different condition below.
4. formula further can be write as:
u i＝Re 1·i o+ (Re 1+Re 2)/(Re 2+Re 3) ·u o
(1) works as Re 1＞0, Re 2＞0, Re 3＞0 and when being finite value, as can be seen from the above equation, input voltage is the controllable load current i both o, controllable load voltage u again o, be referred to as combination drive is implemented in load.When load short circuits, u o=0, flow through the maximum current i of load Omax=u i/ Re 1; When load open circuit, i o=0, the maximum voltage U in the load Omax=(Re 2+ Re 3)/(Re 1+ Re 2) u iUse as fixed gain amplifier, get generally speaking:
(u Omax)/(i Omax)=R L, i.e. (Re 2+ Re 3)/(Re 1+ Re 2) Re 1=R L
Under this condition, if to the driving (R of loud speaker LBe its nominal impedance), then can reduce greatly because the variation of the power output that loudspeaker impedance causes with frequency change.During practical application, can be with Re 3Change potentiometer into, the gain of circuit is adjusted, realize volume control.
(2) work as Re 1=0; Re 2＞0, Re 3＞0 and when being finite value, then:
u i＝ (Re 2)/(Re 2+Re 3) u o
As can be seen from the above equation, output voltage u iControl load voltage u o, ideally with load impedance R LIrrelevant, be referred to as driven is implemented in load; Work as Re 3, the voltage amplification effect is promptly arranged at＞0 o'clock.During practical application, can be with Re 3Change potentiometer into, the gain of circuit is adjusted, realize volume control.If with Re 3Change into and be promptly to become equalizer amplifier by equalizing network, the structure of equalizing network and element calculate obtaining value method and present negative feedback equalizing network just the same.
(3) work as Re 1＞0 and be finite value, Re 2=0, Re 3During=∞, can get: u i=Re 1I.
Be input voltage u iControl load current i o, ideally with load impedance R LIrrelevant, be referred to as current drives is implemented in load.Work as R L＞Re 1The time, the voltage amplification effect is promptly arranged.During practical application, can be with Re 1Change potentiometer string one fixed resistance into, the gain of circuit is adjusted, implement volume control.If R LBe the magnetic recording head coil, then can obtain the constant-current recording of approximate ideal.
As active part, the same with common penetrating (source) utmost point follower, be more preferably and use two-tube push pull mode and four pipe cross-couplings modes, as described in following scheme 3 and scheme 4, its amplification principle is identical with the single tube mode with output characteristic.
Scheme 3, as shown in Figure 4, this is a kind of complementary push-pull type electric signal amplifier of being made up of two triodes or field effect transistor, two triode BG 2, BG 3Emitter or the source electrode of field effect transistor connect one with scheme 1 in the identical output Control Network of basic output Control Network structure, its biasing circuit has special-purpose bias supply ± E 1, bias supply ± E 1With input signal u iBe attempted by resistance R e altogether 3An end, amplifier tube out-put supply ± E 2With output signal u oBe attempted by resistance R e altogether 3The other end.When not adopting positive-negative power, former-E 1,-E 2Power connection is as corresponding+E 1,+E 2Earth point.Can in the input and output loop, determine capacitance c according to the practical application needs in the circuit iAnd c oChoice.
Scheme 4, as shown in Figure 5, this is a kind of four pipe cross-couplings type electric signal amplifiers of being made up of four triodes or field effect transistor, two triodes of its output or field effect transistor BG 6, BG 7Emitter or source electrode on be connected to one with scheme 1 in the identical output Control Network of basic output Control Network structure, its coupling triode or field effect transistor BG 4, BG 5Has special-purpose bias supply ± E 1, bias supply ± E 1With input signal u iBe attempted by resistance R e altogether 3The other end.When not adopting positive-negative power, former negative supply-E 1,-E 2Joint as corresponding power supply+E 1,+E 2Earth point, can be according to actual needs in input circuit and output loop decision capacitance c i, c oChoice.
Scheme 3 and scheme 4 are basic circuit diagram, during practical application, can add other different biasing circuit as required, and need add equalizing resistance at base (grid) utmost point and emission (source) utmost point because the pipe pairing is bad.In fact, when working in Class A small-signal amplification, particularly for scheme 4, whether the pipe pairing is well very little to the influence of circuit performance index, is convenient to produce in batches.Certainly, good pairing has everything to gain and nothing to lose in performance.
It needs to be noted, when as high-power output stage, add equalizing resistance (when working in Class A or class AB state at emission (source) utmost point, for the stability of working, concerning bipolar transistor, be absolutely necessary) influence of output Control Network output characteristic be can not ignore, when not applying loop feedback, Re 1Can partly or entirely replace, so the way of output just has only the output of mixing and electric current to export two kinds by penetrating (source) utmost point equalizing resistance; When adopting field effect transistor, if not high, do not add the source electrode equalizing resistance to stability requirement, can under the condition that does not apply loop feedback, obtain voltage output, there is not this problem when applying loop feedback.Can output characteristic as requested select different component values for use to basic output Control Network.Also can not establish independent bias supply in addition as scheme 1 in scheme 3 and the scheme 4, in addition, pipe can adopt multiple tube.
Several embodiment are provided below:
Embodiment 1, and as shown in Figure 6, it is a magnetic head playback equalizer amplifier, and it is made up of two-stage four pipe cross coupled amplifiers, has also provided its cascade system simultaneously, level bias supply behind the prime out-put supply double as, and the rest may be inferred more than three grades.
Embodiment 2, and as shown in Figure 7, this is a power amplifier that is made of bipolar transistor.Four triodes of front constitute common cross-couplings emitter follower, play impedance conversion and zero-bit corrective action, W 1Adjust potentiometer for zero-bit, when not requiring higher input impedance, can save.In addition, the adjustment of complete machine zero-bit can be used the zero-bit servo circuit that integrated transporting discharging constitutes instead.W 2For the output stage static working current is adjusted potentiometer, W 3Be volume control potentiometer, preferably select exponential type for use.Its output stage is the four pipe cross-couplings type amplifiers that are made of six triodes (compound), and this circuit adopts hybrid mode to the driving of loud speaker.
Embodiment 3, and as shown in Figure 8, this is a power amplifier that is made of the reinforced insulation gate field-effect transistor.W 1Adjust potentiometer for zero-bit, also can use the zero-bit servo circuit instead; W 2For static working current is adjusted potentiometer; W 3Be volume control potentiometer, preferably select exponential type for use.This circuit drives loud speaker ground and adopts hybrid mode.When removing the source electrode equalizing resistance, the driving of loud speaker is become the voltage way of output.
Embodiment 4, as shown in Figure 9, it is a combination type power amplifier that constitutes with integrated transporting discharging, has provided the method that amplifying circuit involved in the present invention applies loop feedback simultaneously, has also solved with amplifier and has made the problem that power amplifier can not be improved by amplifier output voltage power-limiting.Pipe and efferent duct pairing be good when recommending, and when being operated in Class A or class AB state, can adopt the minor loop shown in the dotted line to feed back.The electric current way of output is adopted in driving to loud speaker.
Concrete application circuit is a lot, only lifts this several examples, the top example application circuit of a sound channel that all only drawn.When making the dual track amplifier, left and right sound channels can only have one place (this common place shell of meeting sb. at the airport, can shared wherein one group of power supply) altogether at most.For with existing acoustic product compatibility, as the magnetic head playback equalizer amplifier of signal source, can be with the output stage power sharing; As power amplifier, can be with input stage power sharing (certainly, preferably left and right sound channels be independent fully, promptly has only place and a common source not altogether).Because the end left and right sound channels of inputing or outputing of existing acoustic product all is common ground generally speaking.When connecting with it, this point promptly becomes the common place of the unique permission of dual track circuit involved in the present invention.

Claims (5)

1, a kind of electric signal amplifier of being made up of single triode or field effect transistor, it is characterized in that: the emitter of triode BG1 or the source electrode of field effect transistor are connected to one by resistance R e 1, Re 2, Re 3With load resistance R LThe basic output Control Network of forming, wherein resistance R e 2, Re 3And R LConstitute a △ l network, this △ l network and resistance R e 1Series connection, Re 1Simultaneously with triode BG 1Emitter or the source electrode of field effect transistor join input signal u iEarth point be connected on resistance R e 3An end, power supply+E 2With output signal u oBe attempted by resistance R e altogether 3The other end.
2, electric signal amplifier according to claim 1 is characterized in that: biasing circuit meets another bias supply+E 1, bias supply+E 1With input signal U iAltogether.
3, a kind of complementary push-pull type electric signal amplifier of being made up of two triodes or field effect transistor is characterized in that: two triode BG 2, BG 3Emitter or the source electrode of field effect transistor connect one by resistance R e 1, Re 2, Re 3With load resistance R LThe basic output Control Network that constitutes, wherein resistance R e 2, Re 3And R LConstitute a △ l network, this △ l network and resistance R e 1Series connection, Re 1Join with the emitter of triode or the source electrode of field effect transistor simultaneously, its biasing circuit can have bias supply+E 1Or ± E 1, bias supply+E 1Or ± E 1With input signal u iBe attempted by resistance R e altogether 3An end, out-put supply+E 2Or ± E 2With output signal U oBe attempted by resistance R e altogether 3The other end.
4, a kind of four pipe cross-couplings type electric signal amplifiers of being made up of four triodes or field effect transistor is characterized in that: two triodes of its output or field effect transistor BG 6, BG 7Emitter or source electrode on be connected to one by resistance R e 1, Re 2, Re 3With load resistance R LThe basic output Control Network that constitutes, wherein resistance R e 2, Re 3And R LConstitute a △ l network, this △ l network and resistance R e 1Series connection, Re 1Simultaneously with triode or field effect transistor BG 6, BG 7Emitter or source electrode join its coupling triode or field effect transistor BG 4, BG 5Can have bias supply+E 1Or ± E 1, bias supply+E 1Or ± E 1With input signal u iBe attempted by resistance R e altogether 3An end, out-put supply+E 2Or ± E 2With output signal u oBe attempted by resistance R e altogether 3The other end.
5, according to any described electric signal amplifier among the claim 1-4, it is characterized in that: in its input circuit and output loop, be serially connected with a capacitance C respectively iAnd C o
CN 94111130 1994-08-22 1994-08-22 Electric signal amplifier Pending CN1103519A (en)

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Application Number Priority Date Filing Date Title
CN 94111130 CN1103519A (en) 1994-08-22 1994-08-22 Electric signal amplifier

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Application Number Priority Date Filing Date Title
CN 94111130 CN1103519A (en) 1994-08-22 1994-08-22 Electric signal amplifier

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CN1103519A true CN1103519A (en) 1995-06-07

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100424993C (en) * 2002-05-30 2008-10-08 日本电气株式会社 Feedback amplifier having amplified signal path and feedback signal path separated
CN103178788A (en) * 2013-01-29 2013-06-26 嘉兴联星微电子有限公司 Wide power supply voltage working low noise amplifier bias circuit

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100424993C (en) * 2002-05-30 2008-10-08 日本电气株式会社 Feedback amplifier having amplified signal path and feedback signal path separated
CN103178788A (en) * 2013-01-29 2013-06-26 嘉兴联星微电子有限公司 Wide power supply voltage working low noise amplifier bias circuit
CN103178788B (en) * 2013-01-29 2016-05-04 嘉兴联星微电子有限公司 A kind of low-noise amplifier biasing circuit of wide power voltage power supply

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