CN216086595U - Automatic adjustment A class circuit - Google Patents

Automatic adjustment A class circuit Download PDF

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CN216086595U
CN216086595U CN202121826986.XU CN202121826986U CN216086595U CN 216086595 U CN216086595 U CN 216086595U CN 202121826986 U CN202121826986 U CN 202121826986U CN 216086595 U CN216086595 U CN 216086595U
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circuit
output stage
resistor
electrically connected
output
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温上凯
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Dongguan Kaiyun Technology Co ltd
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Dongguan Kaiyun Technology Co ltd
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Abstract

The utility model discloses an automatic adjustment A-type circuit, which comprises: the pre-stage amplifying circuit is electrically connected with an alternating current feedback network and a direct current feedback network; the output stage bias circuit is electrically connected with the output end of the front-stage amplifying circuit; the output stage bootstrap circuit is electrically connected with the output end of the front-stage amplification circuit and is electrically connected with the output stage bias circuit; the output stage current feedback circuit is electrically connected with the output stage bias circuit and the output stage bootstrap circuit; the output stage circuit is electrically connected with the output stage bias circuit and the output stage feedback circuit; the output stage is always in a dynamic class A working state, the cut-off/switch distortion of the transistor is avoided, and the replaced output effect is obtained.

Description

Automatic adjustment A class circuit
Technical Field
The utility model relates to the technical field of amplifying circuits, in particular to an automatic adjustment A-type circuit.
Background
The existing amplifying circuits, especially the amplifying circuits of class a, class AB and class B, generally cannot completely and continuously maintain the class a operating state, and meanwhile, the transistors are turned on/off during the operation process, so that switching distortion is generated, which directly results in that the optimal audio performance cannot be obtained.
Meanwhile, in order to obtain a better output effect, the conventional circuit adopts a relatively complex circuit structure, so that the volume of the circuit is increased, the production cost is increased, and meanwhile, the maximum volume is limited to a certain degree, so that the use experience of consumers is poor.
Accordingly, there is a need for an auto-tune class a circuit that addresses one or more of the above problems.
Disclosure of Invention
To address one or more of the problems of the prior art, the present invention provides an automatic class a adjustment circuit. The technical scheme adopted by the utility model for solving the problems is as follows: a self-adjusting class a circuit, comprising: the pre-stage amplifying circuit is electrically connected with an alternating current feedback network and a direct current feedback network;
an output stage bias circuit electrically connected to an output of the pre-amplifier circuit, the output stage bias circuit comprising: the output stage comprises an operating point dynamic bias circuit of the output stage and a static operating point bias circuit of the output stage, wherein the static operating point bias circuit of the output stage is arranged in the operating point dynamic bias circuit of the output stage;
the output stage bootstrap circuit is electrically connected with the output end of the front-stage amplification circuit and is electrically connected with the output stage bias circuit;
the output stage current feedback circuit is electrically connected with the output stage bias circuit and the output stage bootstrap circuit;
and the output stage circuit is electrically connected with the output stage bias circuit and the output stage feedback circuit.
Further, the static operating point biasing circuit of the output stage is composed of: the first triode, the second resistor and the third resistor;
the second resistor is connected with the third resistor in series, the base electrode of the first triode is electrically connected with the output end of the second resistor and the input end of the third resistor, and the collector electrode of the first triode and the input end of the second resistor are electrically connected together and electrically connected with the output end of the pre-stage amplifying circuit.
Further, the dynamic operating point biasing circuit of the output stage is composed of: the output stage bootstrap circuit and the output stage feedback circuit are arranged in a dynamic working point biasing circuit of the output stage;
an input end of the fourth capacitor is electrically connected with a collector of the first triode, an input end of the second resistor and an output end of the preceding stage amplifying circuit, an output end of the fourth capacitor is electrically connected with an output end of the third resistor, an input end of the fourth resistor and an emitter of the first triode together, the fourth resistor is connected with the fifth resistor in series, and an output end of the fifth capacitor is electrically connected with an output end of the fourth resistor and an input end of the fifth resistor;
the fourth capacitor and the peripheral components form the output stage bootstrap circuit, and the fifth capacitor and the peripheral components form the output stage current feedback circuit.
Furthermore, the output stage circuit is composed of a second triode, a third triode, a sixth resistor and a seventh resistor;
the positive and negative power supply ends of the output stage circuit are electrically connected with the output stage bias circuit, the output stage circuit is provided with a signal output end, and the signal output end is directly connected with a load or is electrically connected with a vibration damping network firstly and then is electrically connected with the load.
Further, the second triode is of an NPN type, the third triode is of a PNP type, bases of the second triode and the third triode are respectively electrically connected to the output stage bias circuit, a collector of the second triode is a positive power source terminal, and a collector of the third triode is a negative power source terminal;
the sixth resistor and the seventh resistor are connected in series between the emitter of the second triode and the emitter of the third triode;
and the output end of the sixth resistor and the input end of the seventh resistor are the signal output ends.
Furthermore, the preceding stage amplifying circuit is electrically connected with a volume potentiometer.
Furthermore, the output end of the dc feedback network, the output end of the ac feedback network, the output end of the output stage feedback circuit, and the signal output end of the output stage circuit are electrically connected to a tenth resistor, and the tenth resistor is electrically connected to ground.
Further, the pre-stage amplification circuit includes: a preamplifier;
the alternating current feedback network is formed by connecting a second capacitor and a ninth resistor in series, the direct current feedback network comprises a first resistor, the first resistor is a direct current negative feedback resistor of the preamplifier, and the second capacitor is a direct current isolation capacitor and an alternating current signal bypass capacitor.
Further, a first pole of the preamplifier is electrically connected with a first capacitor; the second pole of the preamplifier is electrically connected with a third capacitor; the first capacitor and the third capacitor are frequency compensation capacitors.
Furthermore, an eighth capacitor and a ninth capacitor are respectively electrically connected to two ends of the positive power supply and the negative power supply of the output stage circuit, and the eighth capacitor and the ninth capacitor are power supply decoupling capacitors.
The utility model has the following beneficial values: according to the utility model, the pre-stage amplifying circuit, the output stage bias circuit, the output stage circuit and other circuits are connected together through a smart layout, and the working point dynamic bias circuit of the output stage, the working point static bias circuit of the output stage, the output stage bootstrap circuit and the output stage feedback circuit are arranged in cooperation with the layout of components, so that each sub-circuit in the main circuit can share part of components on the premise of ensuring the use effect, and the circuit volume is reduced; and the switching tubes (the second switching tube and the third switching tube) of the output stage can not enter a cut-off region, and the lowest conducting current is always maintained to the maximum signal to temporarily maximize the conducting current, so that the output stage has no on/off switching distortion of the transistor, the output signal distortion is smaller, the work is more stable, and the output effect is better. The practical value of the utility model is greatly improved.
Drawings
FIG. 1 is a schematic block diagram of an auto-tune class A circuit of the present invention;
FIG. 2 is a schematic diagram of an auto-tune class A circuit according to the present invention;
FIG. 3 is a diagram of a current waveform of a collector of a second triode of an auto-tuning class A circuit according to the present invention;
FIG. 4 is a diagram of a current waveform for automatically adjusting the emitter of the second triode of the class A circuit according to the present invention;
FIG. 5 is a waveform of the current at the collector of the third transistor of the auto-tuning class A circuit according to the present invention;
FIG. 6 is a waveform diagram of the current of the emitter of the third transistor of the auto-tuning class A circuit according to the present invention.
101. front stage amplifying circuit
102. AC feedback network
103. DC feedback network
201. output stage bias circuit
301. output stage bootstrap circuit
401. output stage feedback circuit
501. output stage circuit.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
As shown in fig. 1-2, the present invention discloses an automatic adjusting class a circuit, which includes: a pre-amplifier circuit 101, wherein the pre-amplifier circuit 101 is electrically connected with an alternating current feedback network 102 and a direct current feedback network 103;
an output stage bias circuit 201, wherein the output stage bias circuit 201 is electrically connected to an output terminal of the pre-stage amplifier circuit 101, and the output stage bias circuit 201 comprises: the output stage comprises an operating point dynamic bias circuit of the output stage and a static operating point bias circuit of the output stage, wherein the static operating point bias circuit of the output stage is arranged in the operating point dynamic bias circuit of the output stage;
the output stage bootstrap circuit 301, the output stage bootstrap circuit 301 is electrically connected to the output end of the previous stage amplification circuit 101, and the output stage bootstrap circuit 301 is electrically connected to the output stage bias circuit 201;
an output stage feedback circuit 401, where the output stage feedback circuit 401 is electrically connected to the output stage bias circuit 201 and the output stage bootstrap circuit 301;
and the output stage circuit 501, wherein the output stage circuit 501 is electrically connected with the output stage bias circuit 201 and the output stage feedback circuit 401. The output stage circuit 501, the ac feedback network 102, the dc feedback network 103, and the pre-stage amplifier circuit 101 are grounded.
Specifically, as shown in fig. 2, the dynamic operating point bias circuit of the output stage consists of: a fourth capacitor C04, a fifth capacitor C05, a second resistor R02, a third resistor R03, a fourth resistor R04, a fifth resistor R05, and a first triode Q301, where the output stage bootstrap circuit 301 and the output stage feedback circuit 401 are disposed in a dynamic operating point bias circuit of the output stage;
an input end of the fourth capacitor C04 is electrically connected to a collector of the first transistor Q301, an input end of the second resistor R02 and an output end of the pre-stage amplifier circuit 101, an output end of the fourth capacitor C04 is electrically connected to an output end of the third resistor R03, an input end of the fourth resistor R04 and an emitter of the first transistor Q301, the fourth resistor R04 is connected in series with the fifth resistor R05, an output end of the fifth capacitor C05 is electrically connected to an output end of the fourth resistor R04 and an input end of the fifth resistor R05, and the fifth resistor R05 is electrically connected to the output stage circuit 501;
the fourth capacitor C04 and the peripheral devices constitute the output stage bootstrap circuit 301, and the fifth capacitor C05 and the peripheral devices constitute the output stage current-stage feedback circuit 401.
Specifically, as shown in fig. 2, the static operating point bias circuit of the output stage is composed of: the circuit comprises a first triode Q301, a second resistor R02 and a third resistor R03;
the second resistor R02 is connected in series with the third resistor R03, the base of the first triode Q301 is electrically connected to the output terminal of the second resistor R02 and the input terminal of the third resistor R03, and the collector Q301 of the first triode and the input terminal of the second resistor R02 are electrically connected together and electrically connected to the output terminal of the pre-amplifier circuit 101.
Specifically, as shown in fig. 2, the output stage circuit 501 is composed of a second transistor Q302, a third transistor Q303, a sixth resistor R06, and a seventh resistor R07;
two ends of a positive power supply and a negative power supply of the output stage circuit 501 are electrically connected with the output stage bias circuit 201, the output stage circuit 501 is provided with a signal output end, and the signal output end is directly connected with a load or is electrically connected with a vibration elimination network firstly and then is electrically connected with the load;
specifically, the second triode Q302 is an NPN type, the third triode Q303 is a PNP type, bases of the second triode Q302 and the third triode Q303 are respectively electrically connected to the output stage bias circuit 201, a collector of the second triode Q302 is a positive power source VCC, and a collector of the third triode Q303 is a negative power source VEE;
the sixth resistor R06 and the seventh resistor R07 are connected in series between the emitter of the second transistor Q302 and the emitter of the third transistor Q303;
the output end of the sixth resistor R06 and the input end of the seventh resistor R07 are the signal output ends;
the base electrode of the second triode Q302 is electrically connected with the collector electrode of the first triode Q301, and the base electrode of the third triode Q303 is electrically connected with the emitter electrode of the first triode Q301.
Specifically, as shown in fig. 2, the preamplifier circuit 101 is electrically connected to volume potentiometers, VR01 and VR02 respectively, and the volume potentiometers are connected to the signal input end; an output end of the dc feedback network 103, an output end of the ac feedback network 102, an output end of the output stage feedback circuit 401, and a signal output end of the output stage circuit 501 are electrically connected to a tenth resistor R10, the tenth resistor R10 is electrically connected to ground, that is, the tenth resistor R10 is electrically connected to an output end of the ninth resistor R09, an output end of the first resistor R01, the signal output end, and an input end of the fifth capacitor C05.
Specifically, as shown in fig. 2, the pre-amplifier circuit 101 includes: a preamplifier PreAMP; a first pole of the preamplifier PreAMP is electrically connected with a first capacitor C01; a second pole of the preamplifier PreAMP is electrically connected with a third capacitor C03; the first capacitor C01 and the third capacitor C03 are frequency compensation capacitors.
The preamplifier PreAMP is electrically connected to a positive power supply and a negative power supply, the capacitor C06 and the capacitor C07 are power decoupling capacitors, a positive signal input terminal (in-phase terminal) of the preamplifier PreAMP is electrically connected to a volume potentiometer and an input terminal of the capacitor C01 of the preamplifier circuit 101, a negative signal input terminal (in-phase terminal) of the preamplifier PreAMP is electrically connected to an output terminal of the capacitor C01, an input terminal of the second capacitor C02 and an input terminal of the first resistor R01, an output terminal of the preamplifier PreAMP is electrically connected to an input terminal of the capacitor C03 of the preamplifier circuit 101, an output terminal of the capacitor C03 is connected to the dc feedback network 103 (the input terminal of the first resistor R01), and an output terminal of the preamplifier PreAMP is connected to the output stage bias circuit 201 (the input terminal of the fourth capacitor C04, the input terminal of the second resistor R02 and the input terminal of the output stage bias circuit 201) The collector of the first triode Q301 and the base of the second triode Q302 are electrically connected).
The alternating current feedback network 102 is formed by connecting a second capacitor C02 and a ninth resistor R09 in series, the direct current feedback network 103 comprises a first resistor R01, the first resistor R01 is a direct current negative feedback resistor of the preamplifier, and the second capacitor C02 is a direct current isolation capacitor and an alternating current signal bypass capacitor.
Specifically, as shown in fig. 2, an eighth capacitor C08 and a ninth capacitor C09 are electrically connected to two ends of the positive power supply and the negative power supply of the output stage circuit 501, respectively, and the eighth capacitor and the ninth capacitor are power supply decoupling capacitors. The signal output end; the vibration elimination network comprises: the inductor L01 is connected in parallel with the eighth resistor R08 and then connected in series with the resistor RL, which is grounded, and it should be noted that the resistor RL generally refers to a load.
The direct current gain of the direct current negative feedback two-sum circuit of the preamplifier is determined by the resistance values of the first resistor R01 and the tenth resistor R10, the alternating current negative feedback quantity and the alternating current gain of the circuit are determined by the resistance values of the first resistor R01 and the tenth resistor R10, and the low-frequency response of the alternating current negative feedback network is determined by the capacities and the resistance values of the second capacitor C02, the ninth resistor R09 and the tenth resistor R10; in fig. 2, the sixth capacitor C06 and the seventh capacitor C07 are power decoupling capacitors of the preamplifier.
It should be noted that, the working point dynamic bias circuit of the output stage cooperates with the output stage bootstrap circuit and the output stage feedback circuit to automatically adjust the working current of the output stage circuit according to the output voltage amplitude of the preamplifier PreAMP, so that the output stage circuit is in a dynamic class a working state consistently. Because the output stage is a push-pull circuit, the output power signal is dynamically pushed and pulled out by the second triode Q302 and the third triode Q303 of the output stage; particularly, in the positive half cycle or the negative half cycle of the signal, due to the action of the operating point dynamic bias circuit of the output stage, the second triode Q302 and the third triode Q303 do not enter the cut-off region, but always maintain the lowest conduction current to the maximum signal for the temporary maximum conduction current.
As shown in fig. 3 to 6, the sine wave signal of 1kHz @5Vpp is inputted in the circuit shown in fig. 2 to flow through the second transistor Q302 (fig. 3 corresponds to the current waveform of the collector Ic of the second transistor Q302, and fig. 4 corresponds to the current waveform of the emitter Ie of the second transistor Q302), and the sine wave signal of 1kHz @5Vpp is inputted in the circuit shown in fig. 2 to flow through the third transistor Q303 (fig. 5 corresponds to the current waveform of the collector Ic of the third transistor Q303, and fig. 6 corresponds to the current waveform of the emitter Ie of the third transistor Q303).
It can be seen that, in the positive half cycle of the signal, the current of about 0.8mA still flows in the third transistor Q303 at the lowest, and in the negative half cycle of the signal, the current of about 0.8mA still flows in the second transistor Q302 at the lowest, so neither the second transistor Q302 nor the third transistor Q303 enters the cut-off region. Therefore, the amplifier of the output stage adopting the operating point dynamic bias circuit of the output stage has no distortion of the on/off switch of the transistor.
Based on the circuit structure shown in fig. 2, the output stage bias circuit is generally suitable for being used in combination with high-impedance input stages such as JFETs, MOSFETs, and the like + an ac and dc hybrid negative feedback circuit using deep dc negative feedback. When the circuit is used with a non-high impedance input stage, an active servo circuit is required to compensate the DC offset voltage at the output end in addition to an AC and DC mixed negative feedback circuit. When the circuit structure is changed, particularly the output stage circuit is changed, the circuit form of the output stage bias circuit also needs to be changed correspondingly, but the principle is not changed, and the main frame of the circuit is also the bootstrap circuit and the feedback circuit.
In summary, the pre-amplifier circuit 101, the output stage bias circuit 201, the output stage circuit 501 and other circuits are connected together through a smart layout, and a working point dynamic bias circuit of the output stage, a working point static bias circuit of the output stage, the output stage bootstrap circuit and the output stage feedback circuit are arranged in cooperation with the layout of components, so that each sub-circuit in the main circuit can share part of components on the premise of ensuring the use effect, thereby reducing the circuit volume; and the switching tubes (the second switching tube and the third switching tube) of the output stage can not enter a cut-off region, and the lowest conducting current is always maintained to the maximum signal to temporarily maximize the conducting current, so that the output stage has no on/off switching distortion of the transistor, the output signal distortion is smaller, the work is more stable, and the output effect is better. The practical value of the utility model is greatly improved.
The above-described examples merely represent one or more embodiments of the present invention, which are described in greater detail and detail, but are not to be construed as limiting the utility model. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the spirit of the utility model, which falls within the scope of the utility model. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims (10)

1. An auto-tune class a circuit, comprising: the pre-stage amplifying circuit is electrically connected with an alternating current feedback network and a direct current feedback network;
an output stage bias circuit electrically connected to an output of the pre-amplifier circuit, the output stage bias circuit comprising: the output stage comprises an operating point dynamic bias circuit of the output stage and a static operating point bias circuit of the output stage, wherein the static operating point bias circuit of the output stage is arranged in the operating point dynamic bias circuit of the output stage;
the output stage bootstrap circuit is electrically connected with the output end of the front-stage amplification circuit and is electrically connected with the output stage bias circuit;
the output stage current feedback circuit is electrically connected with the output stage bias circuit and the output stage bootstrap circuit;
and the output stage circuit is electrically connected with the output stage bias circuit and the output stage feedback circuit.
2. An auto-adjusting class a circuit as claimed in claim 1, wherein the static operating point bias circuit of the output stage is comprised of: the first triode, the second resistor and the third resistor;
the second resistor is connected with the third resistor in series, the base electrode of the first triode is electrically connected with the output end of the second resistor and the input end of the third resistor, and the collector electrode of the first triode and the input end of the second resistor are electrically connected together and electrically connected with the output end of the pre-stage amplifying circuit.
3. An auto-adjusting class a circuit as claimed in claim 2, wherein the dynamic operating point bias circuit of the output stage is comprised of: the output stage bootstrap circuit and the output stage feedback circuit are arranged in a dynamic working point biasing circuit of the output stage;
an input end of the fourth capacitor is electrically connected with a collector of the first triode, an input end of the second resistor and an output end of the preceding stage amplifying circuit, an output end of the fourth capacitor is electrically connected with an output end of the third resistor, an input end of the fourth resistor and an emitter of the first triode together, the fourth resistor is connected with the fifth resistor in series, and an output end of the fifth capacitor is electrically connected with an output end of the fourth resistor and an input end of the fifth resistor;
the fourth capacitor and the peripheral components form the output stage bootstrap circuit, and the fifth capacitor and the peripheral components form the output stage current feedback circuit.
4. The automatic adjusting class A circuit of claim 1, wherein the output stage circuit is composed of a second triode, a third triode, a sixth resistor and a seventh resistor;
the positive and negative power supply ends of the output stage circuit are electrically connected with the output stage bias circuit, the output stage circuit is provided with a signal output end, and the signal output end is directly connected with a load or is electrically connected with a vibration damping network firstly and then is electrically connected with the load.
5. The automatic class a circuit of claim 4, wherein bases of the second transistor and the third transistor are electrically connected to the output stage bias circuit, respectively, a collector of the second transistor is a positive power source terminal, and a collector of the third transistor is a negative power source terminal;
the sixth resistor and the seventh resistor are connected in series between the emitter of the second triode and the emitter of the third triode;
and the output end of the sixth resistor and the input end of the seventh resistor are the signal output ends.
6. The automatic class a circuit of claim 1, wherein the preamplifier circuit is electrically connected to a volume potentiometer.
7. The automatic class a circuit of claim 1, wherein the output of the dc feedback network, the output of the ac feedback network, the output of the output stage feedback circuit, and the signal output of the output stage circuit are electrically connected to a tenth resistor, and the tenth resistor is electrically connected to ground.
8. The automatic class a circuit of claim 1, wherein the pre-amplifier circuit comprises: a preamplifier;
the alternating current feedback network is formed by connecting a second capacitor and a ninth resistor in series, the direct current feedback network comprises a first resistor, the first resistor is a direct current negative feedback resistor of the preamplifier, and the second capacitor is a direct current isolation capacitor and an alternating current signal bypass capacitor.
9. The automatic class a circuit of claim 8, wherein the first pole of the preamplifier is electrically connected to a first capacitor; the second pole of the preamplifier is electrically connected with a third capacitor; the first capacitor and the third capacitor are frequency compensation capacitors.
10. The automatic class a circuit of claim 1, wherein an eighth capacitor and a ninth capacitor are electrically connected to two ends of the positive power supply and the negative power supply of the output stage circuit, respectively, and the eighth capacitor and the ninth capacitor are power supply decoupling capacitors.
CN202121826986.XU 2021-08-05 2021-08-05 Automatic adjustment A class circuit Active CN216086595U (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202121826986.XU CN216086595U (en) 2021-08-05 2021-08-05 Automatic adjustment A class circuit

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Application Number Priority Date Filing Date Title
CN202121826986.XU CN216086595U (en) 2021-08-05 2021-08-05 Automatic adjustment A class circuit

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CN216086595U true CN216086595U (en) 2022-03-18

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