CN101702786B - Surround sound effect enhancing circuit - Google Patents

Abstract

The invention relates to a surround sound effect enhancing circuit, the highpass filtering to master signals of a left channel and a right channel is carried out by inputting a primary filtering circuit, the difference value of the signals of the left channel and the right channel is simultaneously acquired by a different value sampling circuit, the filtering treatment to a different value signal is carried out by a secondary filtering circuit, the difference value signal is respectively overlaid to the filtered master signals of the left channel and the right channel and then output, therefore, the surround sound effect is enhanced. The invention has the advantages of simple structure and low cost and can be widely applied to audio power circuits of portable devices, such as a mobile phone, and the like.

Description

Stereo surround audio intensifier circuit

Technical field

The present invention relates to a kind of integrated circuit, especially a kind of stereo surround audio intensifier circuit.

Background technology

Early stage owing to be subjected to technology limitation, the mode of people's record and audio plays is based on monophony.Even by two loud speaker playback monophonic signals, we can obviously feel sound from two audio amplifier intermediate transfer in our ear.Monophony lacks the location positioning to sound, and three-dimensional audio technology has then thoroughly changed this situation, and sound is assigned to two independently sound channels in recording process, thereby has reached good sound localization effect.It is particularly useful that this technology seems in Music Appreciation, the audience can clearly tell various musical instruments from direction, thereby make the richer imagination of music, approach impression when participating in the cintest more.But stereosonic defective is also fairly obvious, and the most obvious is exactly the position of audio amplifier to be put have relatively high expectations, and the bad meeting of pendulum position directly influences the expression of sound.A kind of in recent years virtual ring can make the binaural signal after digital processing around sterophonic technique, by about two audio amplifiers, produce three-dimensional around sound field effect.But owing to spatial limitation, left and right sides loudspeaker distance is near excessively on portable set, and its stereophonic effect and 3D surrounding effect also can be greatly affected.Eliminate this influence, traditional solution is to adopt suitable electric-wave filter matrix that binaural audio signal is distinguished filtering, makes left ear only hear the sound that left speaker is sent, and auris dextra is only heard the sound that right speaker is sent.But take this mode need use the digital filter of structure and algorithm more complicated, can't be applied on the portable sets such as mobile phone.

In view of above reason, a kind of simple in structure, stereo surround audio intensifier circuit has just become a kind of demand cheaply.

Summary of the invention

The objective of the invention is to overcome the deficiencies in the prior art, a kind of stereo surround audio intensifier circuit is provided, is a kind of stereo surround audio intensifier circuit simple in structure, with low cost.

According to technical scheme provided by the invention, described stereo surround audio intensifier circuit comprises:

Filter circuit comprises first order input filter circuit and second level filter circuit, and wherein first order filter circuit carries out Filtering Processing to the left and right acoustic channels audio signal, is used to remove low-frequency interference signal; Second level filter circuit carries out Filtering Processing to difference signal;

The difference sample circuit is used to ask for the signal difference of left and right acoustic channels;

Feedback circuit is used to superpose filtered left and right acoustic channels main signal and exports;

Main power amplifier is used to amplify the left and right acoustic channels main signal;

With the first order input filter circuit left and right acoustic channels main signal is carried out filtering simultaneously, get the difference of left and right sound track signals with the difference sample circuit, and difference signal is carried out Filtering Processing with second level filter circuit, be superimposed on filtered left and right acoustic channels main signal respectively by feedback circuit again, finally by main power amplifier output.

Described first order input filter circuit is the single order high pass filter, and generally its cut-off frequency is at 30Hz.

Described second level filter circuit is a bivalent high-pass filter, and generally its cut-off frequency is at 8KHz.The cut-off frequency of described second level filter circuit is adjustable, in order to the stereo of compensating distortion with around audio.

Described difference sample circuit is made of a subtracter.

Described first order input filter circuit gain is for-1.The filter circuit gain of the described second level is for+1.

Advantage of the present invention is: simple in structure, low cost can be widely used in mobile phone, in the audio power circuit of portable set.

Description of drawings

Fig. 1 is a modular structure block diagram of the present invention.

Fig. 2 is a hardware logic diagram of the present invention.

Embodiment

The invention will be further described below in conjunction with drawings and Examples.The present invention proposes a kind of implementation method of circuit of stereo surround audio enhancing, the left and right acoustic channels main signal is being carried out high-pass filtering simultaneously, signal difference to left and right acoustic channels is carried out Filtering Processing, is superimposed on left and right sides main signal then respectively, thereby the stereo surround audio is enhanced.

Stereo surround audio intensifier circuit device of the present invention mainly comprises filter circuit, difference sample circuit, feedback circuit.Wherein the difference sample circuit is used to ask for the signal difference of left and right acoustic channels.And filter circuit comprises first order input filter circuit and second level filter circuit, and first order input filter circuit carries out Filtering Processing to the left and right acoustic channels audio signal respectively, and its cut-off frequency is used to remove low-frequency interference signal at 30Hz.Second level filter circuit carries out Filtering Processing to difference signal, and its cut-off frequency is at 8KHz, is superimposed on filtered left and right acoustic channels main signal by feedback circuit respectively then and exports, thereby the stereo surround audio is enhanced.Feedback circuit is used to superpose filtered left and right acoustic channels main signal and exports.Main power amplifier is used to amplify the left and right acoustic channels main signal.

With the first order input filter circuit left and right acoustic channels main signal is carried out filtering simultaneously, get the difference of left and right sound track signals with the difference sample circuit, and difference signal is carried out Filtering Processing with second level filter circuit, be superimposed on filtered left and right acoustic channels main signal respectively by feedback circuit again.Be superimposed on respectively on the left and right sound track signals by feedback circuit behind the difference signal process difference sample circuit of left and right acoustic channels, form the second order high-pass filtering circuit of a difference, finally by main power amplifier output.

As shown in Figure 1, present embodiment is by power amplifier A, input filter circuit B, and feedback circuit C, functional modules such as difference sample circuit D are formed.Its intermediate power amplifier A and feedback circuit C form conventional power amplification system, and its structure is the AB class.Input filter circuit B and difference sample circuit D are used for audio to be strengthened.

The left and right acoustic channels audio signal at first enters an input filter circuit, and this circuit is a single order high pass filter, respectively the left and right acoustic channels audio signal is carried out Filtering Processing, and its cut-off frequency is $f_{L1}=\frac{1}{{2\mathrm{\&pi;R}}_1{C}_1},$ Generally should be worth about 30Hz, be used for the elimination low-frequency interference signal.Input signal ingoing power amplifier, its signal gain $G_m=\frac{R_3+R_4}{R_1},$ The difference signal of left and right acoustic channels is superimposed on respectively on the left and right sound track signals through the difference sample circuit, forms the second order high-pass filtering circuit of a difference, and its cut-off frequency is ${\mathrm{<figure-callout\; id="2"\; label="f\; L"\; filenames="H2009102331296E00012.png"\; state="\{\{state\}\}">f</figure-callout>}}_L=\frac{1}{{4\mathrm{\&pi;R}}_7{C}_3},$ Generally should value about 8KHz, in actual applications, the C3 value can change according to actual needs within the specific limits, adjusts the cut-off frequency of described second level filter circuit, can be used for the stereo of compensating distortion and around audio.

When physical circuit is used, general

R3＝R4＝R5＝R6＝R7＝R

R1＝R2＝2R

Left and right sides output signal transfer function

OUT(L)＝Z1×IN(L)-Z2×[IN(L)-IN(R)]

OUT(R)＝Z1×IN(R)+Z2×[IN(L)-IN(R)]

Wherein, Z1 is the single order high pass filter, its cut-off frequency $f_{L1}=\frac{1}{{2\mathrm{\&pi;R}}_1{C}_1},$ Signal gain

Gm=-1 (amplitude is identical with original signal, and phase place is opposite)

Z2 is a bivalent high-pass filter, its cut-off frequency $f_L$ $2_{}=\frac{1}{{4\mathrm{\&pi;R}}_7{C}_3}.$ Signal gain

Gm=1 (amplitude is all identical with original signal with phase place)

Claims (7)

1. stereo surround audio intensifier circuit is characterized in that, comprising:

Filter circuit comprises first order input filter circuit and second level filter circuit, and wherein first order input filter circuit carries out Filtering Processing to the left and right acoustic channels main signal, is used to remove low-frequency interference signal; Second level filter circuit carries out Filtering Processing to difference signal;

The difference sample circuit is used to ask for the signal difference of left and right acoustic channels;

Feedback circuit is used for output with second level filter circuit and is superimposed on filtered left and right acoustic channels main signal and exports;

Main power amplifier is used to amplify the left and right acoustic channels main signal;

The output of difference sample circuit connects the input of second level filter circuit, and the output of second level filter circuit is connected the input of feedback circuit with the output of first order input filter circuit, and the output of feedback circuit connects main power amplifier;

With the first order input filter circuit left and right acoustic channels main signal is carried out filtering simultaneously, get the difference of left and right sound track signals with the difference sample circuit, and difference signal is carried out Filtering Processing with second level filter circuit, be superimposed on filtered left and right acoustic channels main signal respectively by feedback circuit again, finally by main power amplifier output.

2. stereo surround audio intensifier circuit as claimed in claim 1 is characterized in that described first order input filter circuit is the single order high pass filter, and its cut-off frequency is at 30Hz.

3. stereo surround audio intensifier circuit as claimed in claim 1 is characterized in that described second level filter circuit is a bivalent high-pass filter, and its cut-off frequency is at 8KHz.

4. stereo surround audio intensifier circuit as claimed in claim 1 is characterized in that described difference sample circuit is made of a subtracter.

5. stereo surround audio intensifier circuit as claimed in claim 1 is characterized in that described first order input filter circuit gain is for-1.

6. stereo surround audio intensifier circuit as claimed in claim 1 is characterized in that the filter circuit gain of the described second level is for+1.

7. stereo surround audio intensifier circuit as claimed in claim 1, the cut-off frequency that it is characterized in that described second level filter circuit is adjustable, in order to the stereo of compensating distortion with around audio.

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