CN204408277U - Power amplifier - Google Patents

Abstract

The utility model discloses power amplifier; comprise two-way power amplification path, multiple automatic level control circuit, current foldback circuit and thermostat; described two-way power amplification path comprises the first power amplification path and the second power amplification path; all automatic level control circuit is connected, connect successively between the driver a and the driver b of the second power amplification path of the first power amplification path current foldback circuit and thermostat on the input of the isolated amplifier a of the first power amplification path with on the input of the isolated amplifier b of the second power amplification path.The utility model is by above-mentioned principle; this power amplifier can under half-bridge mode of operation or full-bridge mode of operation any switching laws; and at the incoming end of power amplifier, corresponding anti-distortion circuit is set; corresponding current foldback circuit and overtemperature protector are set in the power amplifiers; the performance of this power amplifier is more stable, longer service life.

Description

power amplifier

technical field

The utility model relates to the field of audio power amplification, in particular to a power amplifier.

Background technique

  In recent years, with the realization of the advantages of digitalization, many fields that have not yet been digitized are gradually joining the ranks of digitalization. Before the digitized speech signal reaches the analog power amplifier, it must undergo D/A conversion in order to be amplified by the power amplifier. Therefore, from the perspective of the complete digitization process, the digital mode of the power amplifier is imperative. Today's power amplifiers are usually set to a single channel for signal processing and power amplification, and cannot selectively work in a half-bridge or full-bridge mode. In addition, the input level of the front end of the existing power amplifier is prone to saturation distortion due to the high input level of the front stage. Due to the lack of corresponding monitoring mechanism in the power amplifier, the power amplifier is easily affected by the large current in the circuit or the circuit The excessive temperature damage generated in the power amplifier affects the stable operation of the power amplifier.

Utility model content

The technical problem to be solved by the utility model is to provide a power amplifier, which can be switched arbitrarily under the half-bridge working mode or the full-bridge working mode, and a corresponding anti-distortion circuit is set at the access end of the power amplifier. The corresponding over-current protection circuit and over-temperature protector are set in the power amplifier, the performance of the power amplifier is more stable and the service life is longer.

The technical scheme adopted by the utility model to solve the above-mentioned problems is: a power amplifier, including two power amplification paths, a plurality of automatic level control circuits, an overcurrent protection circuit and a temperature controller, and the two power amplification paths include a first The power amplifying path and the second power amplifying path are all connected with an automatic level control circuit on the input end of the isolation amplifier a of the first power amplifying path and the input end of the isolating amplifier b of the second power amplifying path. An overcurrent protection circuit and a temperature controller are serially connected in series between the driver a of the amplification path and the driver b of the second power amplification path. The input audio signal first passes through the automatic level control circuit to avoid the saturation and distortion of the front-end input signal due to too high input level, and prevent distortion, and then input the processed signal to the two power channels respectively. After processing in the amplifying circuit, the sound is output through the speaker. When the output of a single power amplification channel is required, it is only necessary to send an audio signal of equal amplitude and anti-phase at the input end of the two power amplification channels, and connect the load to the output end of the two power amplification channels. Arbitrary switching between half-bridge mode and full-bridge working mode. In order to increase the stability of the power amplifier, an overcurrent protection circuit and a temperature controller are also set between the driver a and the driver b. When the current in the circuit is too large or the temperature in the circuit is too high, the overcurrent protection circuit or the temperature controller The controller will cut off the circuit to avoid damage to the device. When the current returns to normal or the temperature returns to normal, the circuit will resume work to ensure the safety of the device and improve the service life of the power amplifier.

Further, the first amplifying path includes an isolation amplifier a, an error amplifier a, a modulator a, a driver a, a switching amplifier a, a low-pass filter a and a speaker connected in series in sequence, wherein the modulator a is also connected to a triangular wave generator The non-inverting input of the error amplifier a is connected to the isolation amplifier a, the inverting input of the error amplifier a is connected to the common end of the switching amplifier a and the low-pass filter a, and one end of the speaker is also grounded. After the input audio signal is processed by the automatic level control circuit, it is first amplified by the isolation amplifier a and low-pass filtered by the low-pass filter a. The low-pass filter a uses a second-order Butterworth low-pass filter with a cutoff frequency of 37 kHz and a 3 dB bandwidth of 22 kHz. The filtered signal and the feedback audio signal are sent to the error amplifier a for error amplification, and the amplified error audio signal is output. Send the amplified error signal and carrier signal to the pulse width modulator a, and perform NBDD modulation to generate a PWM signal. The carrier signal is a triangular wave signal generated by a triangular wave generator a, and its frequency is adjustable from 230 to 280 kHz. The PWM signal is inserted into the bootstrap combined driver for pre-amplification, and the amplified PWM signal drives the half-bridge switching amplifier a composed of FETs for power amplification, and outputs the power PWM signal through the speaker. The PWM signal amplified by the switching amplifier a is sampled and sent to the error amplifier a as a feedback signal. The power PWM signal is sent to the low-pass filter a to restore the analog audio signal. When it is necessary to bridge the single-channel output, it is only necessary to send an equal-amplitude and anti-phase audio signal to the input terminals of the two half-bridges, and connect the load to the output terminals of the two half-bridges. In order to increase reliability, an overcurrent protection circuit and a temperature controller are also set between the driver a and driver b to help the whole machine find problems in time and accurately, and facilitate module maintenance. The overcurrent protection circuit can be realized by using existing conventional circuits.

Further, the second amplifying path includes an isolation amplifier b, an error amplifier b, a modulator b, a driver b, a switching amplifier b, a low-pass filter b and a speaker connected in series in sequence, and the modulator a is also connected to a triangular wave generator The non-inverting input terminal of the error amplifier b is connected to the isolation amplifier b, the inverting input terminal of the error amplifier b is connected to the common terminal of the switching amplifier b and the low-pass filter b, and one end of the speaker is also grounded. The working principle of the second amplification path is the same as that of the first amplification path.

Further, the automatic level control circuit includes an isolation amplifier A1, a capacitor C1, a capacitor C2, an isolation amplifier A2 and an isolation amplifier A3 connected in sequence, and the processed signal is output from the output terminal of the isolation amplifier A3, and the capacitor C1 and the capacitor The common end of C2 is connected to the pull-down diode D1, the common end of the capacitor C1 and the capacitor C2 is also connected to the inductor L, one end of the inductor L is also connected to the output end of the operational amplifier A4, and the same input end of the operational amplifier A4 is also connected to the diode D2. The cathode and the anode of the diode D2 are connected to the resistor R3, and the resistor R3 is grounded; the pull-down resistor R2 is also connected to the inverting input terminal of the operational amplifier A4; and the resistor R1 is also connected between the same input terminal and the output terminal of the operational amplifier A4. The circuit is first amplified and filtered by the front isolation amplifier A1 and capacitor C1, and then through the attenuation of the diode D1, the amplification comparison of the amplifier A4 and the detection of the diode D2, and then the filter amplification by the capacitor C2, the isolation amplifier A2 and the isolation amplifier A3 The rear output controls PIN attenuation, keeps the output power constant, and prevents saturation distortion due to high input level of the previous stage.

In summary, the beneficial effects of the utility model are:

The utility model is provided with two power amplification paths and an automatic level control circuit. The power amplifier can be switched arbitrarily under the half-bridge working mode or the full-bridge working mode, and a corresponding anti-distortion circuit is set at the access end of the power amplifier. , Set the corresponding over-current protection circuit and over-temperature protector in the power amplifier, the performance of the power amplifier is more stable and the service life is longer.

Description of drawings

Fig. 1 is a block diagram of the utility model;

Fig. 2 is a circuit diagram of automatic level control in Fig. 1 .

Detailed ways

The utility model will be further described in detail below in conjunction with the embodiments and accompanying drawings, but the implementation of the utility model is not limited thereto.

Example 1:

As shown in Figure 1, the utility model includes two power amplification paths, a plurality of automatic level control circuits, an overcurrent protection circuit and a temperature controller, and the two power amplification paths include a first power amplification path and a second power amplification path. The amplifying path is connected with an automatic level control circuit on the input end of the isolation amplifier a of the first power amplification path and the input end of the isolation amplifier b of the second power amplification path, and the driver a of the first power amplification path and the first power amplification path An overcurrent protection circuit and a temperature controller are serially connected in series between the drivers b of the two power amplification paths.

The input audio signal first passes through the automatic level control circuit to avoid the saturation and distortion of the front-end input signal due to too high input level, and prevent distortion, and then input the processed signal to the two power channels respectively. After processing in the amplifying circuit, the sound is output through the speaker. When the output of a single power amplification channel is required, it is only necessary to send an audio signal of equal amplitude and anti-phase at the input end of the two power amplification channels, and connect the load to the output end of the two power amplification channels. Arbitrary switching between half-bridge mode and full-bridge working mode. In order to increase the stability of the power amplifier, an overcurrent protection circuit and a temperature controller are also set between the driver a and the driver b. When the current in the circuit is too large or the temperature in the circuit is too high, the overcurrent protection circuit or the temperature controller The controller will cut off the circuit to avoid damage to the device. When the current returns to normal or the temperature returns to normal, the circuit will resume work to ensure the safety of the device and improve the service life of the power amplifier.

Example 2:

This embodiment is preferably as follows on the basis of Embodiment 1: the first amplification path includes an isolation amplifier a, an error amplifier a, a modulator a, a driver a, a switching amplifier a, a low-pass filter a and a speaker connected in series in sequence, wherein The modulator a is also connected to the triangular wave generator a, the same input terminal of the error amplifier a is connected to the isolation amplifier a, the reverse input terminal of the error amplifier a is connected to the common terminal of the switching amplifier a and the low-pass filter a, and one end of the speaker Also grounded.

After the input audio signal is processed by the automatic level control circuit, it is first amplified by the isolation amplifier a and low-pass filtered by the low-pass filter a. The low-pass filter a uses a second-order Butterworth low-pass filter with a cutoff frequency of 37 kHz and a 3 dB bandwidth of 22 kHz. The filtered signal and the feedback audio signal are sent to the error amplifier a for error amplification, and the amplified error audio signal is output. Send the amplified error signal and carrier signal to the pulse width modulator a, and perform NBDD modulation to generate a PWM signal. The carrier signal is a triangular wave signal generated by a triangular wave generator a, and its frequency is adjustable from 230 to 280 kHz. The PWM signal is inserted into the bootstrap combined driver for pre-amplification, and the amplified PWM signal drives the half-bridge switching amplifier a composed of FETs for power amplification, and outputs the power PWM signal through the speaker. The PWM signal amplified by the switching amplifier a is sampled and sent to the error amplifier a as a feedback signal. The power PWM signal is sent to the low-pass filter a to restore the analog audio signal. When it is necessary to bridge the single-channel output, it is only necessary to send an equal-amplitude and anti-phase audio signal to the input terminals of the two half-bridges, and connect the load to the output terminals of the two half-bridges. In order to increase reliability, an overcurrent protection circuit and a temperature controller are also set between the driver a and driver b to help the whole machine find problems in time and accurately, and facilitate module maintenance. The overcurrent protection circuit can be realized by using existing conventional circuits.

The second amplification path includes an isolation amplifier b, an error amplifier b, a modulator b, a driver b, a switching amplifier b, a low-pass filter b, and a horn connected in series in sequence, wherein the modulator a is also connected to a triangular wave generator b, and the error amplifier The non-inverting input terminal of b is connected to the isolation amplifier b, the inverting input terminal of the error amplifier b is connected to the common terminal of the switching amplifier b and the low-pass filter b, and one end of the speaker is also grounded. The working principle of this amplifying path is the same as that of the first amplifying path. the

The automatic level control circuit includes sequentially connected operational amplifier A1, capacitor C1, capacitor C2, isolation amplifier A2 and isolation amplifier A3, the processed signal is output from the output terminal of the isolation amplifier A3, and connected to the common terminal of capacitor C1 and capacitor C2 The pull-down diode D1 is also connected to the inductor L at the common end of the capacitor C1 and the capacitor C2, and one end of the inductor L is also connected to the output end of the operational amplifier A4, and the negative pole of the diode D2 is also connected to the same input end of the operational amplifier A4, and the diode D2 The positive electrode is connected to the resistor R3, and the resistor R3 is grounded; the pull-down resistor R2 is also connected to the inverting input terminal of the transport amplifier A4; and the resistor R1 is also connected between the same input terminal and the output terminal of the transport amplifier A4. The circuit is first amplified and filtered by the front isolation amplifier A1 and capacitor C1, and then through the attenuation of the diode D1, the amplification comparison of the amplifier A4 and the detection of the diode D2, and then the filter amplification by the capacitor C2, the isolation amplifier A2 and the isolation amplifier A3 The rear output controls PIN attenuation, keeps the output power constant, and prevents saturation distortion due to high input level of the previous stage.

As mentioned above, the utility model can be better realized.

Claims (4)

1. power amplifier; it is characterized in that; comprise two-way power amplification path, multiple automatic level control circuit, current foldback circuit and thermostat; described two-way power amplification path comprises the first power amplification path and the second power amplification path; all automatic level control circuit is connected, connect successively between the driver a and the driver b of the second power amplification path of the first power amplification path current foldback circuit and thermostat on the input of the isolated amplifier a of the first power amplification path with on the input of the isolated amplifier b of the second power amplification path.

2. power amplifier according to claim 1, it is characterized in that, described first amplifies path comprises isolated amplifier a, error amplifier a, modulator a, driver a, switching amplifier a, low pass filter a and the loudspeaker of connecting successively, modulator a wherein also connects triangular-wave generator a, the input in the same way of error amplifier a connects isolated amplifier a, the reverse input end connecting valve amplifier a of error amplifier a and the common port of low pass filter a, loudspeaker one end also ground connection wherein.

3. power amplifier according to claim 1 and 2, it is characterized in that, described second amplifies path comprises isolated amplifier b, error amplifier b, modulator b, driver b, switching amplifier b, low pass filter b and the loudspeaker of connecting successively, modulator a wherein also connects triangular-wave generator b, the input in the same way of error amplifier b connects isolated amplifier b, the reverse input end connecting valve amplifier b of error amplifier b and the common port of low pass filter b, loudspeaker one end also ground connection wherein.

4. power amplifier according to claim 1, it is characterized in that, described automatic level control circuit comprises the isolated amplifier A1 connected successively, electric capacity C1, electric capacity C2, isolated amplifier A2 and isolated amplifier A3, signal after process exports from the output of isolated amplifier A3, pull-down diode D1 is connected with the common port of electric capacity C2 at electric capacity C1, also inductance L is connected with the common port of electric capacity C2 at electric capacity C1, the output of inductance L one end also concatenation operation amplifier A4, the input in the same way of operational amplifier A 4 also connects the negative pole of diode D2, the positive pole contact resistance R3 of diode D2, resistance R3 ground connection, the reverse input end of operational amplifier A 4 also connects pull down resistor R2, contact resistance R1 is gone back between input and output in the same way in operational amplifier A 4.