The two feedback digital audio-frequency power amplifiers of band
Technical field
The utility model relates to the digital audio frequency power amplifier of two feedbacks, the two feedback digital audio-frequency power amplifiers of band of particularly a kind of low distortion and inhibition switching on and shutting down noise.
Background technology
At present, digital technology is being brought into play more and more important effect in modern society, is just becoming requisite part in the life." digital audio frequency power amplifier circuit " is meant with digital technology audio signal handled.The fundamental diagram of modern certain digital audio frequency power amplifier as shown in Figure 1, after its operation principle is input signal process front end circuit filter out noise, input signal and arrive dull system circuit through the signal behind single feedback circuit without the audio signal of lc circuit, make the audio signal of simulation be converted to digital signal through dull system circuit, and final mode with pulse width modulation, drive the high-power MOS field effect transistor, and carry out the audio signal that obtains simulating after the conversion through a lc circuit, and filtering high-frequency impulse composition, drive the loud speaker playback then; The circuit structure of digital audio frequency power amplifier is a front end circuit, modulation circuit, drive circuit is continuous in proper order, one end of modulation circuit, feedback circuit links to each other, the line of the drain electrode line of two metal-oxide-semiconductors in the left side and an end of filter circuit, one end of feedback circuit links to each other, one end of feedback circuit, one end of filter circuit links to each other, four outputs of drive circuit respectively with upper left metal-oxide-semiconductor, upper right metal-oxide-semiconductor, the bottom right metal-oxide-semiconductor, the grid of lower-left metal-oxide-semiconductor links to each other, the source electrode of upper left metal-oxide-semiconductor and upper right metal-oxide-semiconductor links to each other, the lower-left metal-oxide-semiconductor links to each other with the source electrode of bottom right metal-oxide-semiconductor, the line of upper right metal-oxide-semiconductor and bottom right metal-oxide-semiconductor, one end of filter circuit links to each other, and the two ends of filter circuit link to each other with the two ends of load respectively.Compare with traditional analog amplifier, the advantage of digital audio frequency power amplifier is as follows: (1) efficient height, heating is very little when work.(2) power is big, usefulness is high, distortion is low.(3) tonequality is good.Present digital audio frequency power amplifier all is to adopt single feedback technique to realize low distortion, but still has certain distortion; Also occur the musical instrument sound that enriches super low sound signal especially express plentiful inadequately soft phenomenon, its reason is that instantaneous large-current is under-supply; Also there is the switching on and shutting down noise.
Summary of the invention
The objective of the invention is to overcome the shortcoming that prior art exists, provide a kind of volume little, in light weight, low distortion, the firm power output of wide power voltage input, power amplification efficiency is up to more than 90%, the band of no switching on and shutting down noise pair feedback digital audio-frequency power amplifiers.
Purpose of the present invention is achieved through the following technical solutions: the two feedback digital power amplifiers of this band comprise preposition difference channel, modulation circuit, drive circuit, feedback circuit, low-pass filter circuit, load, metal-oxide-semiconductor, it is characterized in that: described modulation circuit is made of preceding modulation circuit, back modulation circuit; Described feedback circuit is made of preceding differential feedback circuit, back differential feedback circuit; Described preposition difference channel, preceding modulation circuit, back modulation circuit, drive circuit connect successively; Described switching power circuit is connected with preposition difference channel, preceding modulation circuit, back modulation circuit respectively; Differential feedback circuit one end is connected with the back modulation circuit before described, and the other end is connected with metal-oxide-semiconductor, low-pass filter circuit; Described back differential feedback circuit one end is connected with preceding modulation circuit, and the other end is connected with low-pass filter circuit, load.
The output of modulation circuit and the two ends of load before the differential feedback circuit is connected in before described, the structure of differential feedback circuit is the output of comparator before described, inductance, preceding modulation circuit links to each other, the inverting input of comparator, inductance, the output of comparator links to each other, the inverting input of comparator, drive axle chip IC 7 links to each other with inductance, the normal phase input end of comparator, IC7IR2010S links to each other, the normal phase input end of comparator, inductance, the LC loop links to each other, the output of IC7, inductance, the LC loop links to each other, the output of IC7, inductance, the LC loop links to each other, line between the line of output of drive axle chip IC 7 and the line of inductance and another output and inductance, the LC loop links to each other, its audio signal is through arriving feedback circuit behind the LC filter circuit, effect is pulse-width modulation part and the integral part that removes through the audio signal of lc circuit, thereby reduced amplifier distortion, improved fidelity.
Described metal-oxide-semiconductor comprises first, second, third, fourth metal-oxide-semiconductor; One end of described back differential feedback circuit is connected in the back modulation circuit, the other end is connected in first, the gate trace and the 3rd of second two metal-oxide-semiconductors, the gate trace of the 4th metal-oxide-semiconductor, the structure of back differential feedback circuit is the output of comparator, inductance, back modulation circuit links to each other, the inverting input of comparator, inductance, the output of comparator links to each other, the inverting input of comparator, inductance, one end and the 3rd of choking-winding, the line of the source electrode line of the 4th metal-oxide-semiconductor is continuous in proper order, the normal phase input end of comparator, inductance, one end and first of choking-winding, the line of the source electrode line of second metal-oxide-semiconductor is continuous in proper order.Its audio signal is just to arrive feedback circuit without LC filtering.Effect is to remove the pulse-width modulation of the audio signal of not passing through lc circuit part and integral part, thereby has reduced amplifier distortion, has improved fidelity.
The two feedback digital power amplifiers of this band also comprise logic control circuit, and described logic control circuit links to each other with the two ends of preceding modulation circuit, load respectively; Second comparator of described logic control circuit and the inverting input line of the 3rd comparator, the in-phase input end of first comparator links to each other, the normal phase input end of the 3rd comparator, inductance, the in-phase input end of first comparator links to each other, the anti-phase comparator of the 4th comparator, inductance, the in-phase input end of first comparator links to each other, the same phase comparator of the 4th comparator, inductance, the in-phase input end of first comparator links to each other, the normal phase input end of the 5th comparator, inductance, the in-phase input end of first comparator links to each other, second, three, the line of the output line of four comparators and the output of the 5th comparator respectively with the base electrode of last triode, the base electrode of following triode links to each other, on, the emitter of the following triode ground connection that links to each other, the in-phase input end of second comparator, inductance, the output of second comparator is continuous in proper order, the 3rd comparator in-phase input end, inductance, the output of the 3rd comparator is continuous in proper order, the 4th comparator normal phase input end, inductance, the output of the 4th comparator is continuous in proper order, the 5th comparator inverting input, inductance is continuous in proper order.By second and third, the work that starts the upper and lower triode and first comparator of the interruption situation of four, five comparators makes power amplifier be in the failure of oscillation state, the prime input signal is quiet, reaches control of switching on and shutting down soft start and mute function.
The two feedback digital audio-frequency power amplifiers of described band also comprise switching power circuit.Described switching power circuit comprises input rectifying filter circuit, switch transformer conversion portion, preposition power supply positive-negative power and the power amplifier power-supply rectifying circuit that links to each other successively; The output of switching power circuit is connected in the source electrode line, second of the first, the 3rd metal-oxide-semiconductor, the source electrode line of the 4th metal-oxide-semiconductor, preceding modulation circuit, back modulation circuit, preposition difference channel.Switching power circuit have four groups of voltages output 80V (7A), output 120V (10A), output+/-12V (0.8A), end input can be imported 90~120V alternating voltage by switching, also can transfer to be input as 200~240V and to exchange input.Described switching power circuit also comprises the feedback protection circuit that is connected between switch transformer conversion portion, preposition power supply positive-negative power and the power amplifier power-supply rectifying circuit; Its effect is to keep stable power voltage and firm power output; Simultaneously also improve switch power efficiency, can reach 79%.
The utility model groundwork principle is: the two feedback digital audio-frequency power amplifiers of band are handled audio signal with modulation circuit, its unmodulated signal mainly is from input and two feedback circuit, make the audio signal of simulation convert digital signal to, and finally come output pulse signal in the pulse width modulation (PWM) mode, drive high-power MOS tube, and after a lc circuit carries out conversion, obtain analog signal and filtering radio-frequency component, the playback of final driving loud speaker, and reach control of switching on and shutting down soft start and mute function by logic control circuit, also have switching power circuit to provide constant power output for amplifier.Thereby the realization low distortion, no switching on and shutting down noise, characteristics such as volume is little, and is in light weight, stable power voltage has kept firm power output.
The utility model has following advantage and effect with respect to prior art: the two feedback circuits of this pair feedback digital audio-frequency power amplifier utilization are with input signal with from the technology that feeds back to amplifier through lc circuit, without the feedback loop signals stack of lc circuit together, thereby reduced amplifier distortion, improved fidelity.In addition, the utility model also comes circuit is carried out logic control by logical circuit, thereby suppresses the switching on and shutting down noise.Power unit adopts switching power supply, the input of wide power voltage, and firm power output, the power utilization rate is improved.
Description of drawings
Fig. 1 is the operation principle circuit diagram of modern certain digital audio frequency power amplifier.
Fig. 2 is the utility model operation principle circuit diagram.
Fig. 3 circuit diagram of the present utility model.
The circuit diagram of of the present utility model pair of differential feedback of Fig. 4.
The circuit diagram of the logic control circuit of Fig. 5 utility model.
The circuit diagram of the Switching Power Supply of Fig. 6 utility model.
Embodiment
Below in conjunction with embodiment and accompanying drawing the utility model is described in further detail.
Embodiment 1
Fig. 2 shows circuit theory of the present utility model, as seen from Figure 2, the two feedback digital audio-frequency power amplifiers of this band are mainly connected to form by preposition difference channel 1, preceding modulation circuit 2, back modulation circuit 3, drive circuit 4, logic control circuit 5, feedback circuit, low-pass filter circuit 13, first metal-oxide-semiconductor 9, second metal-oxide-semiconductor 10, the 3rd metal-oxide-semiconductor 11, the 4th metal-oxide-semiconductor 12, switching power circuit 14, load 7, and wherein feedback circuit mainly is made up of preceding differential feedback circuit 6, back differential feedback circuit 8.
The concrete structure of each circuit module shown in Figure 2 as shown in Figure 3, as seen from Figure 3, preposition difference channel 1 mainly is made up of comparator IC1-C, IC1-D, inductance L 5, L6, L7, L8 etc., and signal is by just anti-phase input, through behind the IC1, reduced the AC noise that causes by input.
Preceding modulation circuit 2 mainly is made up of inductance L 1, L2, comparator IC1-C etc., preceding modulation circuit has connected preceding differential feedback circuit 6, preceding differential feedback circuit 6 feedback signals are analog signal conversion pulse signal through the synthetic horizontal pulse width modulated of going forward side by side of the audio signal of IC1-C and input.Can reduce distortion like this, improve fidelity.
Back modulation circuit 3 mainly is made up of inductance L 3, L4, comparator IC1-D etc., back modulation circuit has connected back differential feedback circuit 8, back differential feedback circuit 8 feedback signals are analog signal conversion pulse signal through the synthetic horizontal pulse width modulated of going forward side by side of the audio signal of IC1-D and input.Can reduce distortion like this, improve fidelity.
Drive circuit 4 mainly is made up of comparator IC4-A, IC-4B, driving half-bridge IC2, IC3, and pulse signal becomes the two-way inversion signal by IC4-B, IC4-A by one the tunnel, drives full bridge switching circuit through IC2, IC3 respectively.
Low-pass filter circuit 13 mainly is made up of choking-winding, inductance, capacitor C 1, C2, C3, C4, C5 etc., signal transformation is become the audio signal and the elimination high-frequency impulse composition of simulation.
The line of first metal-oxide-semiconductor 9 and the source electrode of second metal-oxide-semiconductor 10 links to each other with the normal phase input end of the comparator IC5-B of differential feedback circuit 8, the source electrode line of the 3rd metal-oxide-semiconductor 11 and the 4th metal-oxide-semiconductor 12 links to each other with the inverting input of the comparator IC5-B of differential feedback circuit 8, the drain electrode of the drain electrode of metal-oxide-semiconductor 9, metal-oxide-semiconductor 11 links to each other, the source electrode of the source electrode of metal-oxide-semiconductor 10, metal-oxide-semiconductor 12 links to each other and joins with ground wire, the grid of the grid of metal-oxide-semiconductor 9, metal-oxide-semiconductor 10 all links to each other with driving half-bridge IC3, and the grid of the grid of metal-oxide-semiconductor 11, metal-oxide-semiconductor 12 all links to each other with driving half-bridge IC2.Four metal-oxide-semiconductors are formed full bridge switching circuit, the control that MOS is opened or turn-offs, when metal-oxide- semiconductor 10,12 is opened, modulation signal enters switching circuit, control audio circuit operate as normal, no matter metal-oxide-semiconductor is in working order still by situation, and the power of consumption on metal-oxide-semiconductor is very little, can not produce heat, efficient is also very high.
The concrete structure of the two feedback circuit modules among Fig. 2 as shown in Figure 4, as seen from Figure 4, two feedback circuits are made of preceding differential feedback circuit 6, back differential feedback circuit 8, the output of modulation circuit 2 and the two ends of load 7 before preceding differential feedback circuit 6 is connected in, one end of back differential feedback circuit 8 is connected in back modulation circuit 3, and the other end is connected in the gate trace of metal-oxide- semiconductor 9,10 and the gate trace of metal-oxide- semiconductor 11,12; Preceding differential feedback circuit 6 is by comparator IC5A, inductance L 1, L2, L3, L4, L5, L6, L7, L8, integrated drive axle chip IC 7 (IC7 can adopt IR2010S) is formed, and the audio signal of process LC filter circuit provides a reference voltage through IC7, and signal is synthetic through the IC5-A difference; Back differential feedback circuit 8 is mainly by comparator IC5B, and inductance L 9, L10, L11, L12 form, from terminal out1, out2 output road, be synthesized in conventional synthesizer IC5-B without the audio signal of LC filtering; Two differential feedback circuit of present embodiment have removed the pulse modulation part and the integral part in self feed back loop, thereby have reduced amplifier distortion, have improved fidelity.
The concrete structure circuit of the logic control circuit among Fig. 2 as shown in Figure 5, as seen from Figure 5, logic control circuit mainly is made up of comparator IC8-A, IC8-B, IC8-D, IC6A, triode Q14, Q15.The work that interruption situation by comparator IC8 starts Q14, Q15 and IC6A makes power amplifier be in the failure of oscillation state, and the prime input signal is quiet, reaches control of switching on and shutting down soft start and mute function.
The concrete structure of the switching power circuit among Fig. 2 as shown in Figure 6.By Fig. 1,6 as seen; the switching power circuit of present embodiment comprises 110V or 220V input rectifying filter circuit, switch transformer conversion portion, the positive and negative 12V of preposition power supply and the power amplifier power-supply rectifying circuit that links to each other successively, comprises the feedback protection circuit that is connected between switch transformer conversion portion, the positive and negative 12V of preposition power supply and the power amplifier power-supply rectifying circuit in addition.Wherein the input rectifying filter circuit mainly is made of inductance T204, T205, rectifier bridge D222; The switch transformer conversion portion mainly is made up of transformer T1, T201 partial circuit; Positive and negative 12V of preposition power supply and power amplifier power-supply rectifying circuit mainly are made of jointly rectification two utmost point D216, D217, D218, D219, D213, D212 and inductance T203, L100; Feedback protection circuit comprises that mainly power management chip Q5, light lotus root close chip IC 201, half-bridge driven chip IC 200, inductance T200.The output of switching power circuit, it is the output of positive and negative 12V of preposition power supply and power amplifier power-supply rectifying circuit, be connected in the source electrode line, second of the first, the 3rd metal-oxide-semiconductor, the source electrode line of the 4th metal-oxide-semiconductor, preceding modulation circuit, back modulation circuit, preposition difference channel, to power to them.Switching power circuit have four groups of voltages output 80V (7A), output 120V (90A), output+/-12V (0.8A), end input can be imported 90~120V alternating voltage by switching, also can transfer to be input as 210~240V and to exchange input.Feedback protection circuit detects the output voltage values of positive and negative 12V of preposition power supply and power amplifier power-supply rectifying circuit, and with the signal back switch transformer conversion portion that is detected, by the switch transformer conversion portion feedback signal is handled, thereby made switching power circuit keep stable power voltage and firm power output; Simultaneously also improve switch power efficiency, can reach 79%.
The operation principle of this pair of feedback digital audio-frequency power amplifier is: after the IC1 raising common-mode rejection ratio of power amplifier input signal through preposition difference channel 1, can obtain reducing the signal of the AC hum that causes by input, input signal and the preceding differential feedback circuit 6 of process, the audio signal of back differential feedback circuit 8 is by preceding modulation circuit 2, the IC1-C of back modulation circuit 3, IC1-D becomes pulse signal by analog signal conversion, pulse signal passes through IC4-A, behind the IC4-B, become the output of 2 road inversion signals by 1 the tunnel, respectively through driving half-bridge IC2, IC3 output drives by metal-oxide-semiconductor Q1, Q2, Q3, the full-bridge switch that Q4 formed, again by outputing to load as analog signal behind the low-energy filter 13, and the situation that thrusts of the comparator IC8 by logic control circuit 5 reaches control of switching on and shutting down soft start and mute function, also has switching power circuit by switch transformer voltage to be divided into four groups and offers amplifier.