CN2334121Y

CN2334121Y - High-voltage audio power amplifier without transformer

Info

Publication number: CN2334121Y
Application number: CN 98235298
Authority: CN
Inventors: 刘待秋
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-02-24
Filing date: 1998-02-24
Publication date: 1999-08-18
Anticipated expiration: 2008-02-24

Abstract

The utility model relates to a high-voltage audio power amplifier without transformers. A high beta low withstand voltage (Q1) and (Q3) and high withstand voltage low beta (Q2) and (Q4) are used for forming high withstand voltage high beta quadrupole assemblies (1) and (2) which are connected into a class-B concatenation push-pull operating state. (V2) can provide bias voltage to (Q2). A floating power supply device (3) can provide the bias voltage to (Q4). A power source (V1) can supply electricity to the power amplifier which is joint into a bridge type for outputting the audio voltage of 2960V (P / P). The amplifier can overcome the defects of high-voltage amplification technology brought by the transformers.

Description

Transless high pressure audio-frequency power amplifier

The utility model relates to transless high pressure audio-frequency power amplifier.

The audio voltage that some audio parts need be gone up kilovolt just can be driven.In the prior art, usually the audio frequency transformer of a high transformation ratio of adjunction between the output of a low pressure amplifier and load is realized such driving.The shortcoming of transformer is well-known, and it has limited the reference frequency output of amplifier.If the inductance value of transformer coil is big inadequately, low frequency characteristic can degenerate.Increase inductance value, then leakage inductance can increase again, and the HFS of frequency characteristic again can be low.Secondly, because the magnetization curve of transformer core is non-linear, can produce nonlinear distortion.Again secondly,, the loss in transformer coil and the iron core has reduced the efficient of amplifier, and last, transformer produces phase shift at low frequency and high frequency, makes amplifier be easy to generate self-oscillation when introducing feedback.Therefore, at the low pressure category, there is the audio-frequency power amplifier of transformer not to be used already.And, have the technology of transformer still to be widely used, even the performance of the stubborn and stupid system that affects of the various shortcoming of transformer at the high pressure category.This respect, a typical example is, in order to obtain to drive the needed kilovolt high pressure audio signal that goes up of the splendid electrostatic loudspeaker of acoustical behavior, used an output transformer, the shortcoming of this transformer has almost been offset whole advantages of electrostatic loudspeaker.Notice that this transformer manufacturing process complexity costs an arm and a leg.

Obviously, prior art does not also provide transless high pressure audio-frequency power amplifier.Trace it to its cause, prior art can't provide this amplifier of manufacturing needed, and existing upward kilovolt is withstand voltage, and the transistor device of high current amplification factor is arranged again.Consult published device handbook, the withstand voltage transistor that surpasses kilovolt, its current amplification factor is no more than 20; Current amplification factor surpasses 200 transistor, and it is withstand voltage to be no more than 100 volts.

The utility model adopts device cheap and easy to get, uses special circuit design, for practical application provides a kind of transless high pressure audio-frequency power amplifier, its objective is, drives away transformer and brings various shortcoming for the high pressure amplifying technique.

Fig. 1 in the accompanying drawing is the electrical schematic diagram of transless high pressure audio-frequency power amplifier; Fig. 2 has then introduced an embodiment, below these is made detailed description.

High-voltage audio power amplifier without transformer shown in Figure 1 shows such:

The collector electrode of the low withstand voltage transistor (Q1) of high β is connected with the emitter of high withstand voltage low β transistor (Q2), constitutes high withstand voltage high β transistor four utmost point assemblies (1); The collector electrode of the low withstand voltage transistor (Q3) of high β is connected with the emitter of the transistor (Q4) of high withstand voltage low β, constitutes high withstand voltage high β four utmost point assemblies (2); Capacitor (C2) cross-over connection is between the emitter of the base stage of transistor (Q4) and transistor (Q3), diode (D2) and diode (D3) series connection back cross-over connection between the emitter of the base stage of transistor (Q4) and transistor (Q3), the unsteady charger (3) of resistance (R2) and diode (D2) formation in parallel; The collector electrode of transistor (Q2) is connected by the emitter of diode (D1) with transistor (Q3), resistance (R1) is in parallel with electric capacity (C1), and cross-over connection is in the base stage of the collector electrode and the transistor (Q3) of transistor (Q2), resistance (R4) cross-over connection is in the base stage of transistor (Q3) and the collector electrode of transistor (Q4), power supply (V2) cross-over connection is between the base stage of the emitter of transistor (Q1) and transistor (Q2), resistance (R3) cross-over connection is between the base stage and utmost point electrode of transistor (Q4), voltage stabilizing didoe (D4) cross-over connection is between the emitter of the base stage of transistor (Q4) and transistor (Q3), high voltage source (V1) is system's power supply, by diode (D2), (D3) mid point is drawn output (output), the base stage of transistor (Q1) constitutes transless high pressure audio-frequency power amplifier as input (input).The operation principle of this circuit is such:

Four utmost point assemblies (1) and four utmost point assemblies (2) are connected into Class B series connection symmetrical operation state: four utmost point assembly (1) conductings, and four utmost point assemblies (2) end, and vice versa.Because the transistor (Q2) in the assembly, (Q4) are for supplying the base stage connection, these two transistorized base stages can suck very big electric current during work, be necessary for these two transistorized base stages for this reason the bias generator that can export big electric current is provided.The base potential of transistor (Q2) is constant, can be powered by power supply (V2).(Q4) is quite different for transistor, and the base potential of this pipe is floated, and is difficult to be its simple power supply.Designed unsteady charger (3) for this reason.Now the operation principle to the charger (3) that floats elaborates: when four utmost point assembly (1) conductings, when four utmost point assemblies (2) end, diode (D2) ends, diode (D3) conducting, and this moment, load current was capacitor (C2) charging by output (output) through diode (D3); When four utmost point assembly (2) conductings, when four utmost point assemblies (1) ended, diode (D3) ended, diode (D2) conducting, and output current flows to load through diode (D2), and capacitor (C2) provides bias voltage for the base stage of transistor (Q4); Resistance (R2) is to provide a little current paths between the emitter of output (output) and transistor (Q3) when static in system, with assurance circuit steady operation.

Existing a lot of device can be used for making this amplifier: high β hangs down withstand voltage transistor (Q1), (Q3) can use transistors such as 2N9014; Transistors such as high withstand voltage low β transistor (Q2), (Q4) BU508; Diode (D1), (D2), (D3) can be with transistors such as 1N4148; Voltage stabilizing didoe (D4) can be selected for use between 6V～10V.

Circuit shown in Figure 2 is an embodiment of this utility model, and this embodiment is used to drive electrostatic loudspeaker, now this is made detailed description:

Transless high pressure audio-frequency power amplifier (4) among the figure and another identical transless high pressure audio-frequency power amplifier (5) have been formed a bridge-type transless high pressure audio-frequency power amplifier.With small not being both of circuit shown in Figure 1, resistance (R1) is replaced by a potentiometer, has three electrodes of a transistor (Q5) to receive potentiometer respectively in addition and gets three end points, to improve the thermal stability of circuit.The ratio of feedback resistance (R ') and input resistance (R ") has been determined the multiplication factor of this amplifier, and equation expression is

Av=-(R '/R ") this circuit is not made any changes, as long as the BV of transistor (Q2), (Q4) _CBOSurpass 1650V, β surpasses 10, and the β of transistor (Q1), (Q3) surpasses 300, BV _CEOSurpass 10V, add appropriate signals in this amplifier input terminal (input-) and input (input+), this amplifier just can provide 2960V (P-P) voltage at output (output+) and output (output-) with the index of computing level.

Claims

Transless high pressure audio-frequency power amplifier is characterized by: the collector electrode of transistor (Q1) is connected with the emitter of transistor (Q2); The collector electrode of transistor (Q3) is connected with the emitter of transistor (Q4); Capacitor (C2) cross-over connection is between the emitter of the base stage of transistor (Q4) and transistor (Q3); Diode (D2) and diode (D3) series connection back cross-over connection is between the emitter of the base stage of transistor (Q4) and transistor (Q3); Resistance (R2) is in parallel with diode (D2); The collector electrode of transistor (Q2) is connected by the emitter of diode (D1) with transistor (Q3); Resistance (R1) is in parallel with electric capacity (C1), and cross-over connection is in the base stage of the collector electrode and the transistor (Q3) of transistor (Q2); Resistance (R4) cross-over connection is in the base stage of transistor (Q3) and the collector electrode of transistor (Q4); Power supply (V2) cross-over connection is between the base stage of the emitter of transistor (Q1) and transistor (Q2); Resistance (R3) cross-over connection is between the base stage and utmost point electrode of transistor (Q4); Voltage stabilizing didoe (D4) cross-over connection is between the emitter of the base stage of transistor (Q4) and transistor (Q3); High voltage source (V1) is system's power supply; Draw output (output) by the mid point of diode (D2), (D3); The base stage of transistor (Q1) is as input (input).