CN1750386A - High-fidelity power amplifier of current mode - Google Patents
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- CN1750386A CN1750386A CN 200510039218 CN200510039218A CN1750386A CN 1750386 A CN1750386 A CN 1750386A CN 200510039218 CN200510039218 CN 200510039218 CN 200510039218 A CN200510039218 A CN 200510039218A CN 1750386 A CN1750386 A CN 1750386A
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Abstract
This invention relates to a current mode hi-fi power amplifier composed of an input buffer level, a current transmitter, a transimpedance amplifier, a buffer output level, a negative feedback network and an integrating circuit. This invention discloses the appliance of the current mode technology in sound technology taking current as the variable to process signals in the current domain.
Description
Technical field
Suitable and a kind of high-fidelity power amplifier of current mode of the present invention belongs to the electronic audio technical field.
Background technology
From Edison's invention gramophone in 1877 so far, more than 100 year.Preceding 70 years sound equipment slower development and resting in the ivory tower.Up to nineteen twenty-seven, Bell Laboratory has been invented after epoch-making negative feedback (NFB) technology, and high-fidelity power amplifier just enters the arena of history.Along with electronic device is weeded out the old and bring forth the new, circuit form is updated, and the high-fidelity power amplifier performance improves constantly.People listened to the music with CD in the past, and the performance of traditional senior high-fidelity power amplifier can meet the demands.
According to the impedance difference just of key node in the circuit, traditional high-fidelity power amplifier belongs to the voltage-mode amplifier.It mainly is made up of several parts such as differential input stage, cascode voltage amplifier stage, power output stages.For the high cmrr that obtains amplifier, the linearity that improves input stage, reduce the noise and the DC offset voltage of input stage, the input stage of traditional high-fidelity power amplifier almost all adopts the differential pair tube amplifying circuit without exception, and input signal is cushioned.Voltage amplifier stage is considered to the part of most critical in the high-fidelity power amplifier, and it has determined the frequency response and the distortion of whole amplifier, is made of triode cascode voltage amplifier stage.The power output stage that the output signal of voltage amplifier stage is made of emitter follower provides thousands of times current gain buffering output, drives load.The M22K high-fidelity power amplifier that Japan Pioneer Co., Ltd releases adopts the structure of this classical circuit, makes tonequality reach high boundary, becomes the model of modern high-fidelity power amplifier design; The A-100 amplifier of Japan siren company adopts the two differential input stages of two-stage common-emitter common-base, common-emitter common-base voltage amplifier stage, power tube in parallel output, and the elite of set name machine is the flagship of traditional electrical pressing mold high-fidelity power amplifier.With regard to its circuit essence, still adopt the circuit structure of M22K classics, but used the common-emitter common-base circuit in a large number, and the circuit height symmetry, thereby expanded frequency band, improved the speed of amplifier.But because its element circuit is more fastidious more complicated, also very high to the requirement of device, price is surprising.
1999, Philip and Sony have been developed the high-quality source of sound jointly---SACD (super audio frequency CD), make the frequency band of source of sound extend to 100KHz, dynamic range is up to 120dB, constantly development and perfect of this technology in 4 years afterwards, and, make the SACD machine unknown to the public always in 4 years because equipment such as corresponding wideband power amplifier and wideband audio amplifier are not popularized.Existing 2,000,000 consumers in the whole world have selected the SACD player at present, and the market of SACD is gradually stable, and people are more urgent to the novel high-fidelity power amplifier demand of wideband, high speed.
In addition, transient intermodulation (TIMD) theory that has proposed crystal amplifier from doctor Otalc in 1970 so far, thousands of pieces of writing of the paper that various periodicals are delivered, but never find the simple and effective way of avoiding transient intermodulation.In the face of high-quality source of sound, some has fallen behind traditional amplifier unavoidably.In this case, research and development ultrabroad band, superfast novel high-fidelity power amplification is significant.
Summary of the invention
The objective of the invention is to satisfy high-quality source of sound---the requirements at the higher level of advanced digital sources of sound of new generation such as SACD, DVD-Audio at frequency band and response speed that existing high-fidelity power amplifier exists, the situation of people's demand, and existing senior high-fidelity power amplifier is to the high request of device, the surprising deficiency that waits of price provides ultrabroad band, superfast a kind of high-fidelity power amplifier of current mode.
The objective of the invention is to be achieved through the following technical solutions, a kind of high-fidelity power amplifier of current mode is characterized in that described power amplifier is by the input buffering level, current transmission device, trans-impedance amplifier, the buffering output stage, negative feedback network and integrating circuit are formed; The output of one termination current transmission device of trans-impedance amplifier, the other end connects with the input of buffering output stage; One end ground connection of negative feedback network, the output of another termination buffering output stage of negative feedback network, the inverting input of the middle termination current transmission device of negative feedback network; The output of the one termination buffering output stage of integrating circuit, the inverting input of another termination current transmission device of integrating circuit; The buffering output stage adopts and is no less than secondary Darlington export structure.
The invention discloses the application of current mode technology in sound technique, so-called current-mode high-fidelity power power amplifier is meant with electric current as variable, a kind of novel power amplifier of in current field signal being handled.Current-mode is a kind of high-performance information processing technology emerging in high-speed communication and the Video processing originally.Though the current-mode amplifying technique has bandwidth, fireballing advantage, it is big also to exist offset voltage, the shortcoming of common mode inhibition capacity difference.Particularly it is applied in resistance, inductance, the compound load of electric capacity, device is operated under big electric current, the powerful ill-conditioned condition, and circuit stability is required in the high high-fidelity audio frequency power amplification field, needs to solve many problems.The present invention has taked a series of measures, stably realized super wide passband, at a high speed, low distortion and low noise amplify, its performance has breakthrough raising than traditional electrical pressing mold high fidelity amplifier.
High-fidelity power amplifier of current mode is owing to adopted current mode technology emerging in high-speed communication and the video processing technique, realized super wide passband, at a high speed, low distortion and low noise amplify, its performance has breakthrough raising than conventional voltage pattern high fidelity amplifier.Prime, back level frequency response technical indicator are respectively 3.8MHz and 1.1MHz, and switching rate is 300V/us, far above the high-fidelity power amplifier of the tens thousand of units of import.Under the prerequisite that does not increase cost, realized fast, broadband, high linear high-fidelity audio frequency power amplification.To exert far reaching influence to following high-fidelity audio frequency power amplifier technology.
Description of drawings
Fig. 1 is a circuit structure block diagram of the present invention;
Fig. 2 is an application circuit of the present invention;
Embodiment
Further specify the present invention in conjunction with the accompanying drawings and embodiments, the invention discloses the application of current mode technology in sound technique, so-called current-mode high-fidelity audio frequency power amplifier is meant with electric current as variable, a kind of novel power amplifier of in current field signal being handled.This amplifier is made up of several parts such as input buffering level A1, second generation current transmission device CCII, trans-impedance amplifier I/V, output buffer stage A2, negative feedback network and integrating circuit, and circuit is at different levels all to constitute transconductance linearity (Transliner-TL) loop; Trans-impedance amplifier is a core by building-out capacitor C3, C11, constitutes in conjunction with current transmission device and buffering output stage, and the end of building-out capacitor C3 exchanges ground connection, between the input of the output of another termination current transmission device of building-out capacitor C3 and buffering output stage; Negative feedback network is made up of resistance R 39 and resistance R 41, one end ground connection of resistance R 39, the output of a termination of resistance R 41 buffering output stage, the inverting input that is connected the termination current transmission device of resistance R 39 and resistance R 41, the span of resistance R 41 is 1-2K Ω, and optimum value is 1.21K Ω.
Input signal is sent into CCII second generation current transmission device after being cushioned by A1 input buffering level.Wherein Y is the voltage loader, and X is a current input terminal, is zero input impedance, and the electric current of Low ESR X input will all be sent to high impedance output Z.Simultaneously, the Z end also is the input of transimpedance amplifier I/V, and in the time of dynamically, the high impedance of utilization ' Z ' point is transformed into voltage with the output current IZ of CCII.At last, utilize the output stage A2 buffering output of having only current gain.
Be subjected to the inspiration of classical current-mode amplifier architecture in the field of information processing, design experiences in conjunction with traditional high-fidelity audio frequency power amplifier, and a series of measures below having taked, make the current-mode amplifying technique in high-fidelity audio frequency power amplifier, obtain science and use, improved the performance of amplifier breakthroughly.
1. the upper and lower constant-current source of input stage realizes that by the Widlar current mirror that triode Q1, Q2 and Q12, Q14 form the resistance that changes series resistance R12, R24 in triode Q1, the Q2 common collector can be regulated the quiescent current of input stage easily respectively.Resistance R 12, R24 Standard resistance range are respectively 33-100, and optimum value is 72, and the Widlar current mirror can be guaranteed high stability, low noise and the high current gain of input stage.During the pcb board design, Q1, Q2 and Q12, Q14 are installed respectively face-to-face, make it reach good temperature-compensating, improve the stability of input stage.
2. current-mode high-fidelity audio frequency power amplifier requires the device absolute symmetry, otherwise that the stability of amplifier work will become will be very poor.But be subjected to the influence of device fabrication, absolute symmetry is impossible realize.For this reason, all add emitting stage Current Negative Three-Point Capacitance resistance in the amplifier signal treatment circuit, for each transistor, as resistance R 1, R2, R13, R14 etc.Improved the stability of amplifier greatly.
3. insert building-out capacitor C3, C11 between the b of buffering output stage triode Q6, Q18, the c utmost point, come the frequency response and the switching rate of resonance-amplifier by the capacity of regulating building-out capacitor C3, C11, the range of capacity of building-out capacitor C3, C11 is respectively 15-100Pf, and optimum value is 30Pf.
4. current-mode amplifier offset voltage is big, and is dangerous to audio amplifier.It is core that the author has introduced with integrated circuit (IC) 1 (NE5532), comprises the integrator of peripheral circuit, and offset voltage is dropped to below the ideal value.
5. current-mode amplifier common mode inhibition capacity is poor, and it is the prime power supply that the author has adopted the outstanding tandem stabilized voltage power supply of performance, and the front and back level is powered respectively.
6. in order to reduce the influence of load, adopt three grades of Darlington export structures, and multitube parallel, improved the load driving ability of current-mode high-fidelity power amplifier prime.
7. to be connected to triode Q10 be the V be multiple circuit of core to the input of buffering output stage, during installation triode Q10 also is contained on the radiator of output stage, variable resistor R19 is the quiescent current of scalable output stage between the base stage of adjusting triode Q10 and the emitter, and since the good effect temperature compensation of triode Q10 and output stage transistor, the work of having stablized output stage.The frequency response that current-mode high-fidelity power amplifier is widened amplifier significantly, we know that the audibility range of people's ear is 20Hz-20KHz, if but the performance of only investigating amplifier with the sine wave signal of 20KHz is irrational.At occurring in nature, waveform does not exist for sinusoidal wave pure tone, and this class sound only exists in the artificial test tone.People's ear is different with sinusoidal wave sensation to the square wave of 20KHz, illustrates that the high order harmonic component in the square-wave signal of 20KHz has contribution to the sense of hearing of people's ear.If with the square wave fourier expansion, can obtain the odd-multiple that frequency is a fundamental frequency, and the sine wave that its amplitude descends with the rising of frequency.
Square wave for 20KHz, if amplitude is cast out (for the amplifier of rated power 100W less than 1/50th harmonic components of first harmonic magnitude, the about 0.5V of the voltage magnitude of 51 subharmonic correspondences), then the highest multifrequency sinusoid composition of 20KHz square wave is about 1MHz, promptly should investigate the frequency response requirement of amplifier with the sine wave of 1MHz.
High-fidelity power amplifier of current mode has been realized ultrabroad band, and in the traditional electrical pressing mold amplifier, the impedance of requisite cascode voltage amplifier transistor load is very big, and Miller effect has had a strong impact on high frequency response, and amplifier accomplishes that the broadband amplification is by no means easy.In the current-mode amplifier, its circuit topological structure is different fully with traditional amplifier, influences that electric capacity is operated on the very low node of impedance between the transistor level of speed and bandwidth, and the RC time constant is minimum, according to document, and its closed loop-three dB bandwidth
Only and negative feedback resistor R
fWith the building-out capacitor C that inserts trans-impedance amplifier
TRelevant.Like this, amplifier just can be accomplished ultrabroad band, the ultra-high frequency signal in the perfect replay music.This can guarantee the perfect characteristic of phase place, and this is the basic element that correct sound field is replayed.
High-fidelity power amplifier of current mode does not have the notion that gain bandwidth product is a constant, closed-loop bandwidth BW
fDirectly and R
fAnd C
TProduct be inversely proportional to, with closed loop gain A
UfIrrelevant, the GBW (gain bandwidth product) of the fidelity of electric current altitude touch in other words audio amplifier is big more than common electrical pressing mold amplifier, and not have GBW be the constraint of constant, realizes the independent regulation of gain and bandwidth.
Current-mode high-fidelity power amplifier is effectively avoided transient intermodulation, if high-frequency when output of handling zooming pulse and large amplitude with amplifier, except the bandwidth of amplifier, the characteristic that is called as switching rate also plays an important role.When input signal contained the very high transient pulse of speed, traditional amplifier was limited by the restriction to electric current of current source and load capacitance, and output just can not obtain due output voltage immediately, and input stage can not in time obtain due negative feedback voltage.In this moment, amplifier is in negative feedback open loop situations out of control, the instantaneous serious overload of input stage, and output causes the transition pulses transient distortion with serious slicing, this is called transient intermodulation.Transient intermodulation is given not feeling soon of " metallic sound ", causes the obvious deterioration of tonequality, is commonly called as to be " transistor sound ".The means of avoiding transient intermodulation of current trend are to adopt shallow negative feedback, local negative feedback even do not have the negative feedback design, but these or be not radical solving method, the cost of perhaps for this reason paying is high.
The current-mode power amplifier has been eliminated transient intermodulation, and the circuit structure of current-mode amplifier is different fully, does not have the restriction to electric current of current source and load capacitance.According to document, current-mode amplifier switching rate
With the input signal amplitude linear growth, during the large-signal input, the switching rate of current-mode amplifier is more much bigger than traditional amplifier.We can regulate negative feedback resistor R
fWith building-out capacitor C
TParameter, expand the bandwidth of amplifier significantly, realize the ultrahigh speedization of amplifier, thoroughly eliminate transient intermodulation, guaranteed that the current-mode amplifier has high-frequency signal low distortion play capability significantly.For example international top Denmark " Gui Feng " amplifier product all has the characteristic of super wealthy frequency range, has significantly strengthened amplifier to high speed transient Signal Processing ability.
The full power bandwidth of current-mode power amplifier approaches closed-loop bandwidth, with S
RThe expression of substitution full power bandwidth,
The full power bandwidth that is the current-mode amplifier approaches closed-loop bandwidth, has realized the high-performance power amplification of high-power, high frequency, low distortion.
Claims (9)
1, a kind of high-fidelity power amplifier of current mode is characterized in that described power amplifier is by comprising the input buffering level, current transmission device, buffering output stage, trans-impedance amplifier, negative feedback network and integrating circuit composition; The output of one termination current transmission device of trans-impedance amplifier, the other end connects with the input of buffering output stage; One end ground connection of negative feedback network, the output of another termination buffering output stage of negative feedback network, the inverting input of the middle termination current transmission device of negative feedback network; The output of the one termination buffering output stage of integrating circuit, the inverting input of another termination current transmission device of integrating circuit; The buffering output stage adopts and is no less than secondary Darlington export structure.
2, high-fidelity power amplifier of current mode according to claim 1, it is characterized in that trans-impedance amplifier is a core by building-out capacitor C3, C11, constitute in conjunction with current transmission device and buffering output stage, the end of building-out capacitor C3 exchanges ground connection, between the input of the output of another termination current transmission device of building-out capacitor C3 and buffering output stage.
3, high-fidelity power amplifier of current mode according to claim 1, it is characterized in that negative feedback network is made up of resistance R 39 and resistance R 41, one end ground connection of resistance R 39, the output of the one termination buffering output stage of resistance R 41, resistance R 39 is connected the inverting input of termination current transmission device with resistance R 41, the span of resistance R 41 is 1-2K Ω.
4, high-fidelity power amplifier of current mode according to claim 1, the upper and lower constant-current source that it is characterized in that the input buffering level is realized by the Widlar current mirror that triode Q1, Q2 and Q12, Q14 form respectively, the resistance that changes series resistance R12, R24 in triode Q1, the Q2 common collector is regulated the quiescent current of input stage, resistance R 12 and R24 resistance summation scope are 33-100KQ, during the pcb board design, triode Q1, Q2 and Q12, Q14 are installed respectively face-to-face.
5, high-fidelity power amplifier of current mode according to claim 1 is characterized in that each triode all adds emitting stage Current Negative Three-Point Capacitance resistance in the described amplifier signal treatment circuit.
6, high-fidelity power amplifier of current mode according to claim 1, it is characterized in that cushioning between the b, the c utmost point of output stage triode Q6, Q18 and insert building-out capacitor C3, C11, by frequency response and switching rate that the capacity of control capacittance C3, C11 comes resonance-amplifier, the range of capacity of building-out capacitor C3, C11 is respectively 15-100Pf.
7, high-fidelity power amplifier of current mode according to claim 1 is characterized in that integrating circuit is a core with integrated circuit (IC) 1 (NE5532), comprises peripheral circuit.
8, high-fidelity power amplifier of current mode according to claim 1 is characterized in that cushioning output stage multitube parallels at different levels.
9, high-fidelity power amplifier of current mode according to claim 1, it is the V be multiple circuit of core that the input that it is characterized in that cushioning output stage is connected to triode Q10, during installation triode Q10 is contained on the radiator of buffering output stage, variable resistor R19 changes the quiescent current of buffering output stage between the base stage of adjusting triode Q10 and the emitter, the work that output stage is stablized in the temperature-compensating of triode Q10 and buffering output stage transistor.
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| CN 200510039218 CN1750386A (en) | 2005-04-30 | 2005-04-30 | High-fidelity power amplifier of current mode |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015139352A1 (en) * | 2014-03-18 | 2015-09-24 | 王丰硕 | Current analog audio amplifier |
| CN109194296A (en) * | 2018-09-20 | 2019-01-11 | 上海艾为电子技术股份有限公司 | A kind of audio-frequency power amplifier |
| CN110442896A (en) * | 2019-05-31 | 2019-11-12 | 天津大学 | Resistance-the voltage conversion circuit compensated with process deviation and temperature deviation |
| CN114421903A (en) * | 2021-12-30 | 2022-04-29 | 王仲季 | A conversion circuit using common base as the front stage V/I and the rear stage as I/V |
-
2005
- 2005-04-30 CN CN 200510039218 patent/CN1750386A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015139352A1 (en) * | 2014-03-18 | 2015-09-24 | 王丰硕 | Current analog audio amplifier |
| CN109194296A (en) * | 2018-09-20 | 2019-01-11 | 上海艾为电子技术股份有限公司 | A kind of audio-frequency power amplifier |
| CN110442896A (en) * | 2019-05-31 | 2019-11-12 | 天津大学 | Resistance-the voltage conversion circuit compensated with process deviation and temperature deviation |
| CN110442896B (en) * | 2019-05-31 | 2023-03-31 | 天津大学 | Resistor-voltage conversion circuit with process deviation and temperature deviation compensation |
| CN114421903A (en) * | 2021-12-30 | 2022-04-29 | 王仲季 | A conversion circuit using common base as the front stage V/I and the rear stage as I/V |
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