CN201656921U - Filter circuit - Google Patents
Filter circuit Download PDFInfo
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- CN201656921U CN201656921U CN2010201199503U CN201020119950U CN201656921U CN 201656921 U CN201656921 U CN 201656921U CN 2010201199503 U CN2010201199503 U CN 2010201199503U CN 201020119950 U CN201020119950 U CN 201020119950U CN 201656921 U CN201656921 U CN 201656921U
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- 239000003990 capacitor Substances 0.000 abstract description 28
- 238000001914 filtration Methods 0.000 abstract description 5
- 239000010752 BS 2869 Class D Substances 0.000 abstract 1
- 230000007547 defect Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 2
- 230000005236 sound signal Effects 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000000295 complement effect Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000012797 qualification Methods 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- PICXIOQBANWBIZ-UHFFFAOYSA-N zinc;1-oxidopyridine-2-thione Chemical class [Zn+2].[O-]N1C=CC=CC1=S.[O-]N1C=CC=CC1=S PICXIOQBANWBIZ-UHFFFAOYSA-N 0.000 description 1
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Abstract
The utility model relates to a low-pass filter circuit applied to the output end of a digital audio-frequency amplifier. In allusion to the defects of big volume and high cost of the filter circuit in the prior art, the utility model discloses a class-D audio-frequency amplifier output low-pass filter circuit. The utility model has the technical scheme that the two terminals of the input end of the filter circuit are respectively connected with the two output ends of a BTL (Bridge-Tied-load) amplifier, and the two terminals of the output ends of the filter circuit are connected with a loudspeaker. The utility model is characterized in that the two terminals of the input ends of the filter circuit are non-homonymous ends in two sets of coils in a differential mode inductor respectively; another two non-homonymous ends of the two sets of coils of the differential mode inductor are the output ends of the filter circuit; the output ends are in parallel connection with a first capacitor; and the two terminals of the output ends are respectively earthed through a second capacitor and a third capacitor. The utility model is mainly used for digital audio-frequency amplifier output filtering.
Description
Technical field
The utility model relates to a kind of output circuit of digital audio amplifier, particularly a kind of low-pass filter circuit that is applied to the digital audio amplifier out.
Background technology
At present, in audio-visual productss such as panel TV set, the application of switching mode audio-frequency power amplifier (D genus audio power amplifier, or D class A amplifier A) is very general.Because the power consumption of D class A amplifier A is lower, can realize higher efficient, and can reduce the size of radiator and the area of PCB, thereby can reduce system cost, helps the miniaturization of product.In order further to raise the efficiency and to be convenient to integratedly, BTL (Bridge-Tied-load bridge-tied load) circuit-mode is adopted in D class A amplifier A output usually, and the two ends of load (loud speaker SPK) are connected on the output of two amplifiers respectively.The output of one of them amplifier is the mirror image output of another one amplifier, that is to say that the signal that is added in the load two ends differs 180 ° on phase place, will obtain 2 times of voltages of original single-ended output in the load.The power output of circuit will increase by 4 times theoretically.The BTL circuit can make full use of system voltage, so the BTL structure often is applied in low-voltage system or the battery power supply system.The BTL amplifier of describing in the utility model all refers to the D class A amplifier A of sort circuit pattern.Nowadays panel TV and consumer audio product all adopt this class A amplifier A mostly.The D class A amplifier A is intended to realize the efficient amplification of signal based on the digital modulation technique that uses high switching frequency signal.Modulating frequency is usually up to hundreds of kHz, this head and shoulders above audiorange.Owing to need recover the realAudio signal from digitlization or modulation signal, thereby must adopt two output low pass filters to come the filtering high fdrequency component, with the real simulation signal of regenerating and the human auditory system is complementary.
Prior art generally all is to adopt two independent power inductances to constitute the LC low pass filter to realize one road sound accompaniment output, and Fig. 1 shows this circuit theory diagrams.Among the figure, inductance L 1, L2 are two power inductances, and capacitor C 1, C2, C3 can select high frequency porcelain chip capacitor or patch capacitor etc. for use.Inductance and electric capacity constitute the LC low pass filter among Fig. 1, and the signal of BTL amplifier output is by above-mentioned filter filtering high-frequency modulation signal, and audio signal then can drive loud speaker (SPK) sounding by filter.This filter circuit need take bigger pcb board space, row's plate difficult wiring, and increased cost, bring difficulty for the miniaturization Design of product.Also have a kind of employing special integrated chip to cooperate the peripheral components active filter circuit, its shortcoming is the circuit structure complexity, and components and parts are more, and the cost height also is unfavorable for the miniaturization of product.
The utility model content
Technical problem to be solved in the utility model is exactly big at the filter circuit volume of prior art, and the shortcoming that cost is high improves a kind of D class audio amplifier output low-pass filter circuit.
The technical scheme that the utility model solve the technical problem employing is, a kind of filter circuit, two terminals of described filter circuit input connect two outputs of BTL amplifier respectively, two terminals of described filter circuit output connect loud speaker, it is characterized in that, two terminals of described filter circuit input are respectively the non-same polarity of two groups of coils in the differential mode inductance, and two other non-same polarity of two groups of coils of described differential mode inductance is the output of filter circuit; Described output the 1st electric capacity in parallel, two terminals of described output are respectively by the 2nd electric capacity and the 3rd capacity earth;
Concrete, described differential mode inductance is to be produced on the chip inductor that two groups of coils on the same magnetic core constitute;
Concrete, described the 2nd electric capacity is the model electric capacity identical with parameter with the 3rd electric capacity;
Further, described the 2nd electric capacity and the 3rd electric capacity are parallel with the RC series circuit respectively;
Further, described the 2nd electric capacity has identical structural parameters and electric parameter with the RC series circuit of the 3rd electric capacity parallel connection.
The beneficial effects of the utility model are, adopt a differential mode inductance, just can effectively substitute two power inductances of prior art, not only saved valuable pcb board space, circuit structure is also simpler, and cost is lower, and the circuit parameter configuration easily, and output is stable, reliable.Be adapted at promoting the use of in the audio-visual productss such as panel TV set, help to promote the complete machine quality of product.
Description of drawings
Fig. 1 is the circuit theory diagrams of prior art;
Fig. 2 is the circuit theory diagrams of the utility model embodiment.
Embodiment
Below in conjunction with drawings and Examples, describe the technical solution of the utility model in detail.
The technical solution of the utility model adopts the identical differential mode inductance of power inductance in the filter circuit of a size and prior art, utilizes two groups of coils of differential mode inductance and electric capacity to form the LC low-pass filter circuit.The non-same polarity of two groups of coils in the differential mode inductance, as the input of filter circuit, connect two outputs of BTL amplifier respectively, make the two-way inversion signal of BTL amplifier output, can pass through filter circuit filtering high-frequency modulation signal smoothly, reduction audio-signal-driven loud speaker.
Embodiment
This routine filter circuit comprises differential mode inductance L1, the 1st capacitor C the 1, the 2nd capacitor C the 2, the 3rd capacitor C 3 as shown in Figure 2, and resistance R 1, the RC series circuit of capacitor C 4 compositions and the RC series circuit that resistance R 2, capacitor C 5 are formed.Among Fig. 2, differential mode inductance L1 is produced on the chip inductor that two groups of coils on the same magnetic core constitute.1 pin of differential mode inductance L1 and 4 pin are end of the same name; 2 pin and 3 pin are end of the same name.The non-same polarity of two groups of coils among the differential mode inductance L1 (1 pin among Fig. 2,2 pin) is the filter circuit input, two outputs that connect the BTL amplifier respectively, two other non-same polarity of two groups of coils among the differential mode inductance L1 (3 pin among Fig. 2,4 pin) is the output of filter circuit, connects two terminals of loud speaker (SPK) respectively.The 1st capacitor C 1 is connected in parallel on the filter circuit output, and two terminals of output are also respectively by the 2nd capacitor C 2 and the 3rd capacitor C 3 ground connection.Consider the symmetrical structure of BTL amplifier, and the characteristic of output signal, the 2nd capacitor C 2 of this example is selected the model electric capacity identical with parameter for use with the 3rd capacitor C 3.In the filter circuit shown in Figure 2, the 2nd capacitor C 2 and the 3rd capacitor C 3 are parallel with the RC series circuit of resistance R 1, capacitor C 4 compositions and the RC series circuit that resistance R 2, capacitor C 5 are formed respectively.Consider that based on identical symmetry above-mentioned two RC series circuits have identical structural parameters and electric parameter, promptly resistance R 1, resistance R 2 are selected same model and parameter for use, and capacitor C 4, capacitor C 5 are selected same model and parameter for use.For the ease of carrying out the mounted on surface of PCB, all elements of this routine filter circuit all can adopt surface mount elements.Component parameters can be according to concrete BTL amplifier condition of work among the figure, and specification requirement is selected.General the 2nd capacitor C the 2, the 3rd capacitor C 3 has than high capacitance, be mainly used in low frequency filtering (less than 10kHz), capacitor C 4, the less ceramic condenser of capacitor C 5 capacitances, be used for High frequency filter (＞300kHz), the RC series circuit of capacitor C 2, capacitor C 3 parallel connections can better be restrained the parasitic higher-order of oscillation.
The foregoing description only shows the filter circuit of a certain sound channel, can follow the prescribed rules for other sound channels.The foregoing description only is used to describe the utility model, does not represent qualification of the present utility model, and the various variations that those skilled in the art carry out according to foregoing description are all in the utility model protection range.
Claims (5)
1. filter circuit, two terminals of described filter circuit input connect two outputs of BTL amplifier respectively, two terminals of described filter circuit output connect loud speaker, it is characterized in that, two terminals of described filter circuit input are respectively the non-same polarity of two groups of coils in the differential mode inductance, and two other non-same polarity of two groups of coils is the output of filter circuit in the described differential mode inductance; Described output the 1st electric capacity in parallel, two terminals of described output are respectively by the 2nd electric capacity and the 3rd capacity earth.
2. a kind of filter circuit according to claim 1 is characterized in that, described differential mode inductance is to be produced on the chip inductor that two groups of coils on the same magnetic core constitute.
3. a kind of filter circuit according to claim 1 and 2 is characterized in that, described the 2nd electric capacity is the model electric capacity identical with parameter with the 3rd electric capacity.
4. a kind of filter circuit according to claim 3 is characterized in that, described the 2nd electric capacity and the 3rd electric capacity are parallel with the RC series circuit respectively.
5. a kind of filter circuit according to claim 4 is characterized in that, described the 2nd electric capacity has identical structural parameters and electric parameter with the RC series circuit of the 3rd electric capacity parallel connection.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010201199503U CN201656921U (en) | 2010-02-26 | 2010-02-26 | Filter circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010201199503U CN201656921U (en) | 2010-02-26 | 2010-02-26 | Filter circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201656921U true CN201656921U (en) | 2010-11-24 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2010201199503U Expired - Fee Related CN201656921U (en) | 2010-02-26 | 2010-02-26 | Filter circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201656921U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102946187A (en) * | 2012-11-27 | 2013-02-27 | 上海斐讯数据通信技术有限公司 | Circuit and method for eliminating power noise |
-
2010
- 2010-02-26 CN CN2010201199503U patent/CN201656921U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102946187A (en) * | 2012-11-27 | 2013-02-27 | 上海斐讯数据通信技术有限公司 | Circuit and method for eliminating power noise |
| CN102946187B (en) * | 2012-11-27 | 2015-11-25 | 上海斐讯数据通信技术有限公司 | A kind of circuit and method eliminating power supply noise |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20101124 Termination date: 20180226 |