CN101052111A - Stereo playing system for mobile TV - Google Patents
Stereo playing system for mobile TV Download PDFInfo
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- CN101052111A CN101052111A CN 200710097609 CN200710097609A CN101052111A CN 101052111 A CN101052111 A CN 101052111A CN 200710097609 CN200710097609 CN 200710097609 CN 200710097609 A CN200710097609 A CN 200710097609A CN 101052111 A CN101052111 A CN 101052111A
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- power amplifier
- play system
- cabling
- difference
- stereo
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Abstract
The invention comprises: a D class amplifier; and a resonant circuit between the output of the amplifier and a stereo speaker or a earphone, which is used for removing EMI interference; the self-resonance point of the resonant circuit is at 470 MHZ where the maximum interference is generated; by the resonant circuit, the falling of receiving sensitivity caused by D class amplifier can be avoided.
Description
Technical field
The present invention relates to mobile TV, be specifically related to a kind ofly under the prerequisite that guarantees present mobile TV receiving sensitivity and result of broadcast, obviously reduce the power consumption of Play System, prolong the stereo playing system for mobile TV of the reproduction time of terminal.
Background technology
Mobile TV is a kind of emerging technology, allow the consumer can be whenever and wherever possible TV reception easily.DVB-H (handheld digital video broadcast standards) is widely used at present in numerous technical standards that can realize this function, and many terminals have been arranged on market, and is wherein general with Digital Video Broadcasting Handheld especially.Experience for the user has reasonable sound shadow, terminal all is to adopt stereo playing system.Because the electric energy of the portable set that moves is very limited, and the power consumption of stereo playing system proportion in this type of TV applications is very big, account for about 70%, therefore, the power consumption that reduces this Play System is for important effect is arranged the service time that prolongs terminal.Usually the audio frequency power amplifier that is adopted is a class ab ammplifier, and its efficient is not high, and it is exactly fine arriving 55%, and in fact can only accomplish 50%.Adopt D class power amplifier, just can bring up to more than 85%.But D class power amplifier has its disadvantageous one side, will bring powerful electromagnetic interference EMI, causes the receiving sensitivity on some frequency range to reduce.
Summary of the invention
The technical issues that need to address of the present invention provide a kind of stereo playing system for mobile TV, can adopt D class power amplifier to reduce system power dissipation, avoid powerful EMI to disturb simultaneously, and further conformance with standard is to the requirement of receiving sensitivity.
Above-mentioned technical problem of the present invention solves like this, a kind of stereo playing system for mobile TV is provided, use stereo loudspeaker or earphone, adopt D class digital power amplifier, comprise that also being arranged on being used between described power amplifier output and stereo loudspeaker or the earphone eliminates reflection and the attenuator circuit that EMI disturbs.
According to Play System provided by the invention, the maximum attenuation of described reflection and attenuator circuit point is positioned at the corresponding mobile TV that needs protection arbitrarily and receives frequency range, and such as for European DVB-H mobile TV, this frequency range is exactly 470-862MHZ.
Further, if adopt TI company's T PA2010 power amplifier, the maximum attenuation point of described reflection and attenuator circuit is the 470MHZ that determines the maximum interference place through testing.
According to Play System provided by the invention, described reflection and attenuator circuit are the LC resonant circuits of adopting, and its L element L1～L4 can adopt magnetic bead or inductance, preferentially adopts magnetic bead.
According to Play System provided by the invention, C element C9 in described reflection and the attenuator circuit～C16 adopts difference to touch or common mode capacitance, select the ESR low electric capacity of trying one's best, and its SRF should clearly be chosen in the interfering frequency place simultaneously.According to above principle, can select flexibly according to the actual conditions of separately physical circuit.
According to Play System provided by the invention, the cabling between described power amplifier output and stereo loudspeaker or the earphone meets difference cabling principle, guarantees the geometric area minimum that two differential lines are surrounded in principle that is: as far as possible.Simultaneously, on PCB (printed circuit board (PCB)) layout, the close loudspeaker that D class power discharging device should be tried one's best, the weak point that the output cabling is tried one's best.
According to Play System provided by the invention, described power amplifier is the difference input, and serial connection is used to adjust the RC circuit of power amplifier frequency response and gain on its input.
According to Play System provided by the invention, the cabling of described difference input meets difference cabling principle, guarantees the geometric area minimum that two differential lines are surrounded in principle that is: as far as possible.。
According to Play System provided by the invention, be connected between the power supply of described power amplifier and the ground increase power amplifier PSRR performance move back lotus root capacitor C 5～C8.
According to Play System provided by the invention, described power amplifier and loudspeaker are two, exist in pairs.
Stereo playing system for mobile TV provided by the invention, adopt D class power amplifier, simultaneously mainly adopt resonant circuit, further adopt other EMI suppression measures, can prevent to reduce because of the receiving sensitivity that adopts D class power amplifier to cause, thereby when guaranteeing the quality of reception, reduce power consumption smoothly, prolong the terminal plays time, compared with prior art, following advantage is arranged:
1. receiving sensitivity meets the standard of the ETSI of ETS association fully, does not worsen because adopt D class power amplifier;
2. when the specified output 500mw of monophony, audio-frequency unit power consumption (efficient 85% during the portable terminal actual play, actual power loss is 500mw/0.85=588mW just) and use general A class-b amplifier (efficient 50%, actual power loss is 1000mW) compare and reduce 412mW, the stereo 824mW that just reduces altogether.If adopt 4.0V, the battery of 1000mAh means and will reduce the current drain (824mW/4v=206mA) of 206mA.Prolong reproduction time accounts for 70% of total power consumption with audio-frequency unit and calculates greatly, will prolong about 1 hour.
Description of drawings
Further the present invention is described in detail below in conjunction with the drawings and specific embodiments.
Fig. 1 is the complete circuit design principle schematic diagram that stereo playing system for mobile TV of the present invention adopts D class power amplifier.
Embodiment
As shown in Figure 1, stereo playing system for mobile TV of the present invention comprises D class power amplifier 1, the resonant circuit 2 of its output, by two to (SPKOUT_R+, SPKOUT_R-) and (SPKOUT_L+, SPKOUT_L-) the audio output signal line connects loudspeaker separately respectively, comprises that also four groups of RC circuit 3 of input are serially connected in (LEFT+ respectively, LEFT-) or (RIGHT+ is RIGHT-) on the two pairs of source audio signal difference incoming lines; That the 1 concrete employing of D class power amplifier is TPA2010 among the figure, can also be the satisfactory device of MAX9701 or the like.
Further, specify the technical measures of stereo playing system for mobile TV of the present invention:
(1) capacitor C 5～C8 be as amplifier power supply move back lotus root, be used for increasing the power supply ripple rejection ratio PSRR performance of power amplifier 1, can select flexibly according to the power supply situation that adopts, here we select 4.7uf and 0.1uf.
(2) be connected in series on the source audio signal difference incoming line (R1, C1) and (R2, C2), (R3, C3), (R4, four groups of RC circuit 3 of C4) forming are main with the frequency response and the gain that adjust power amplifier 2.This is the input of fully differential, and antijamming capability is fine, can guarantee audio quality as far as possible.Also can import by the order end simultaneously, can with another termination virtual earth or direct ground connection.
But this dual mode all will note adopting the difference cabling, guarantees the geometric area minimum that two differential lines are surrounded in principle as far as possible.
(3) resonant circuit 2 is used to eliminate the huge EMI interference that D class power amplifier produces, and guarantees not interference receiver frequency band.
Because D class power amplifier 1 is gone out the operating state of switch/end, and power is very big, generally can export 500mw, so its high order frequency will have very big energy.Therefore the present invention to two to (SPKOUT_R+, SPKOUT_R-) and (SPKOUT_L+, SPKOUT_L-) harmonic energy of these on the line deals with.The at first definite frequency range that will protect is selected suitable device then.U wave band in DVB-H uses, we show result of experiment, have very strong interference near 470,000,000, can cause reducing more than 10 db in the receiving sensitivity of this frequency.Therefore at 470Mhz, take removing measure.
First-selected magnetic bead can be converted into heat energy with the part electromagnetic energy of decay target, mainly plays attenuation.Next selects inductance for use, mainly plays reflex.Select for use principle to be exactly, cooperate external circumstances such as cabling, pad, its self-resonance point on the frequency of target decay, can access maximum decay like this.Here, we select the wire-wound inductor of 39nh for use, as the L1 among Fig. 1, and L2, L3 and L4, result of the test can improve 10db with sensitivity.Simultaneously, after stage can add difference and touch and common mode capacitance, once more with the reflection of remaining radio-frequency (RF) energy with consume a part, to C16, this processing of evidence can improve the sensitivity of 1db as the C9 among Fig. 1.
(4) for reaching the effect of best elimination EMI, and this two couple (SPKOUT_R+, SPKOUT_R-) and (SPKOUT_L+, SPKOUT_L-) the output differential lines is also adhered to the principle of difference cabling, guarantees best common mode inhibition effect.
Claims (9)
1, a kind of stereo playing system for mobile TV, use stereo loudspeaker or earphone, it is characterized in that, adopt D class digital power amplifier (1), comprise that also being arranged on being used between described power amplifier (1) output and stereo loudspeaker or the earphone eliminates reflection and the attenuator circuit (2) that EMI disturbs.
According to the described Play System of claim 1, it is characterized in that 2, the maximum attenuation point of described reflection and attenuator circuit (2) is positioned at corresponding mobile TV and receives frequency range.
According to the described Play System of claim 1, it is characterized in that 3, what described reflection and attenuator circuit (2) adopted is the LC resonant circuit, its L element L1～L4 can adopt magnetic bead or inductance.
According to the described Play System of claim 4, it is characterized in that 4, C element C9 in described reflection and the attenuator circuit (2)～C16 adopts difference to touch or common mode capacitance.
According to the described Play System of claim 1, it is characterized in that 5, the cabling between described power amplifier (1) output and stereo loudspeaker or the earphone meets difference cabling principle.
According to the described Play System of claim 1, it is characterized in that 6, described power amplifier (1) is the difference input, serial connection is used to adjust the RC circuit (3) of power amplifier frequency response and gain on its input.
According to the described Play System of claim 7, it is characterized in that 7, the cabling of described difference input meets difference cabling principle.
8, according to the described Play System of claim 1, it is characterized in that, be connected between the power supply of described power amplifier (1) and the ground increase power amplifier PSRR performance move back lotus root capacitor C 5～C8.
According to the described Play System of claim 1, it is characterized in that 9, described power amplifier (1) and loudspeaker are two, exist in pairs.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200710097609 CN101052111A (en) | 2007-04-24 | 2007-04-24 | Stereo playing system for mobile TV |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200710097609 CN101052111A (en) | 2007-04-24 | 2007-04-24 | Stereo playing system for mobile TV |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN101052111A true CN101052111A (en) | 2007-10-10 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200710097609 Pending CN101052111A (en) | 2007-04-24 | 2007-04-24 | Stereo playing system for mobile TV |
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| Country | Link |
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| CN (1) | CN101052111A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102056054A (en) * | 2009-10-30 | 2011-05-11 | 扬智科技股份有限公司 | Sound playing device and compensation method thereof |
| CN104602368A (en) * | 2014-12-18 | 2015-05-06 | 小米科技有限责任公司 | Mobile terminal |
-
2007
- 2007-04-24 CN CN 200710097609 patent/CN101052111A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102056054A (en) * | 2009-10-30 | 2011-05-11 | 扬智科技股份有限公司 | Sound playing device and compensation method thereof |
| CN102056054B (en) * | 2009-10-30 | 2013-09-18 | 扬智科技股份有限公司 | Sound playing device and compensation method thereof |
| CN104602368A (en) * | 2014-12-18 | 2015-05-06 | 小米科技有限责任公司 | Mobile terminal |
| CN104602368B (en) * | 2014-12-18 | 2018-06-08 | 小米科技有限责任公司 | Mobile terminal |
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