CN114157964A - Audio circuit and apparatus - Google Patents
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Abstract
The invention provides an audio circuit and apparatus, wherein the audio circuit comprises: the band elimination filter and the audio power amplification module are connected in series; the band elimination filter is used for filtering components of motor vibration frequency in an original audio signal in an external scene and outputting a vibration-free audio signal to the audio power amplification module, and the audio power amplification module is used for realizing audio output in the external scene. According to the audio circuit and the device, in the external scene, the band elimination filter is adopted to replace the high-pass filter, so that the components of the motor vibration frequency in the original audio signal are filtered. The output vibration-free audio signal can compensate the frequency near the resonant frequency point of the motor filtered by the traditional high-pass filter, so that the low frequency of a part is released, better low-frequency performance is obtained, and the user experience is improved.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to an audio circuit and an audio device.
Background
The trinity speaker is equivalent to the assembly of speaker, earphone, motor, and the inside pronunciation of output of cell-phone baseband chip, music and motor signal are all followed audio signal output, then are connected to trinity speaker output. Therefore, it is necessary to process different signals separately for different application scenarios.
In the scenes that vibration is not needed, such as audio playing and voice communication, the prior art filters the low-frequency component of an audio signal through a high-pass filter, so as to achieve the purpose of filtering the vibration sensation of a motor. In the mode, no matter the low-frequency effect is achieved on voice communication or music playing, subjective low-frequency experience loss of a user is large, and user experience is affected.
Disclosure of Invention
The invention provides an audio circuit and an audio device, which are used for solving the defects that the low-frequency effects of voice communication and music playing in the prior art are poor and the user experience is influenced.
The present invention provides an audio circuit comprising:
the band elimination filter and the audio power amplification module are connected in series;
the band elimination filter is used for filtering components of motor vibration frequency in an original audio signal in an external scene and outputting a vibration-free audio signal to the audio power amplification module, and the audio power amplification module is used for realizing audio output in the external scene.
The audio circuit further comprises a switch module and an earphone access module;
the switch module is used for transmitting the original audio signal to the band elimination filter in the play-out scene and transmitting the original audio signal to the earphone access module in the earphone scene;
the receiver access module is used for realizing audio output in the receiver scene, and the receiver access module and the audio power amplifier module are mutually independent.
According to the audio circuit provided by the invention, the earphone channel module comprises two differential channel circuits and two serially connected bias resistors; the two differential path circuits respectively perform high-pass filtering and impedance matching on two paths of differential signals in the original audio signals;
two ends of the two serially connected bias resistors are respectively connected with connection points of the serially connected capacitors and resistors in the two differential path circuits, and a connection point between the two serially connected bias resistors is connected with a bias voltage.
According to the audio circuit provided by the invention, the audio circuit further comprises a band-pass filter, the band-pass filter is used for controlling the strength of an original motor signal and transmitting the original motor signal to the audio power amplification module, and the audio power amplification module is also used for realizing audio output in a vibration scene.
According to the audio circuit provided by the invention, the audio power amplifier module comprises an enabling end, and the audio power amplifier module is used for determining a current working scene according to the waveform of an enabling signal received by the enabling end and executing the operation corresponding to the current working scene.
According to the audio circuit provided by the invention, if the current working scene is in a multimedia or voice mode, the audio power amplification module amplifies the power of the non-vibration-sense audio signal;
if the current working scene is a vibration scene, the audio power amplification module amplifies the power of the original motor signal;
and if the current working scene is a receiver scene, the audio power amplification module is turned off.
According to the audio circuit provided by the invention, the band elimination filter comprises two differential band elimination filters which respectively carry out band elimination filtering on two paths of differential signals in the original audio signal.
According to an audio circuit provided by the invention, the differential band elimination filter comprises a second-order low-pass filter and a second-order high-pass filter which are connected in parallel.
According to the audio circuit provided by the invention, the second-order low-pass filter comprises a first resistor, a second resistor, a first capacitor and a second capacitor, wherein the first resistor and the second resistor are connected in series; the second-order high-pass filter comprises a third resistor, a fourth resistor, a third capacitor and a fourth capacitor, the third capacitor is connected with the fourth capacitor in series, the third resistor is connected with the fourth resistor in parallel, one end of the third resistor is connected with a connection point of the third capacitor and the fourth capacitor, and the other end of the third resistor is grounded.
The invention also provides an audio device, which comprises the audio circuit and the three-in-one loudspeaker, wherein the three-in-one loudspeaker is connected with the output end of the audio power amplifier module in the audio circuit.
According to the audio circuit and the device, in the external scene, the band elimination filter is adopted to replace the high-pass filter, so that the components of the motor vibration frequency in the original audio signal are filtered. The output vibration-free audio signal can compensate the frequency near the resonant frequency point of the motor filtered by the traditional high-pass filter, so that the low frequency of a part is released, better low-frequency performance is obtained, and the user experience is improved.
Drawings
In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of an audio circuit according to the present invention;
FIG. 2 is a second schematic diagram of the audio circuit according to the present invention;
FIG. 3 is a schematic circuit diagram of a switch module provided by the present invention;
fig. 4 is a schematic circuit design diagram of an earpiece path module provided by the present invention;
FIG. 5 is a schematic diagram of the circuit design of the bandpass filter provided by the present invention;
FIG. 6 is a schematic circuit diagram of an audio power module according to the present invention;
FIG. 7 is a schematic circuit design of a band stop filter provided by the present invention;
fig. 8 is a schematic structural diagram of an audio device provided by the present invention.
Reference numerals:
110: a band-stop filter; 120: an audio power amplifier module; 130: a switch module;
140: an earpiece pass-through module; 150: a band-pass filter; 160: three-in-one loudspeaker.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Three paths of signals inside a mobile phone baseband chip platform: speech, multimedia and motor signals. And (3) finishing the combined output of different scenes through software control: (1) in the scenes such as audio playing, voice communication and the like which do not need vibration, a high-pass filter is opened to filter low-frequency components, so that the aim of filtering the vibration sense of the motor is fulfilled. (2) In a scene of the incoming call ringtone needing to vibrate and play, a high-pass filter and a band-pass filter are simultaneously turned on to output music and motor vibration signals, and at the moment, the incoming call ringtone has both loudspeaker sound and vibration. (3) And under the scene of only needing vibration, only the motor vibration signal is output, and the strength of the motor signal is controlled by the band-pass filter.
In the prior art, only vibration sensation filtering is concerned, the motor vibration sensation is filtered through a high-pass filter with high cut-off frequency, and the subjective low-frequency perception loss of a user is large no matter conversation or music playing is performed, so that the low-frequency effects of voice conversation and music playing are poor. Therefore, it is desirable to design an audio circuit to improve the low frequency effects of voice calls and music playback.
Fig. 1 is a schematic structural diagram of an audio circuit provided in the present invention, and as shown in fig. 1, the audio circuit includes a band-stop filter 110 and an audio power amplifier module 120 connected in series; the band elimination filter 110 is configured to filter components of a motor vibration frequency in an original audio signal in an external playing scene, and output a non-vibration-sensing audio signal to the audio power amplifier module 120, where the audio power amplifier module 120 is configured to implement audio output in the external playing scene.
Specifically, the audio circuit may be suitable for a terminal having a three-in-one speaker, for example, for audio circuit designs of smart phones, tablet computers, wearable electronic devices, or the like.
The play-out scene here refers to a scene that is sounded with a speaker in the terminal. The play-out scene is suitable for multimedia, such as music or video playing, and voice play-out call scenes because the loudness of the play sound of the play-out scene is large. In the playing scene, the requirements on the aspects of tone quality, detail expression, low-frequency expression and the like are high. It should be noted that the play-out scene herein is applicable to a scene that needs play-out but does not need vibration.
Taking a smart phone as an example, the original audio signal may be a differential output of the audio signal output by the baseband chip, and may include a call voice signal and a multimedia playing signal.
The traditional mode of utilizing the very high pass filter of cutoff frequency to filter original audio signal low frequency component has also filtered the low frequency component in the original audio signal when filtering the motor vibration, leads to the subjective low frequency of user to experience the loss than great, no matter be in the conversation or under the external scene of music broadcast, the low frequency effect is all relatively poor.
The band elimination filter 110 is used in the embodiment of the present invention to replace a high pass filter, where the band elimination filter 110 is a filter that can pass most frequency components but filter out frequency components in the vibration range of the motor. The band elimination filter 110 only filters the component of the motor vibration frequency in the original audio signal, and the original audio signal is filtered by the band elimination filter 110 and then outputs the non-vibration audio signal. The non-vibration-sense audio signal can compensate the frequency near the motor resonance frequency point filtered by the traditional high-pass filter, so that partial low frequency is released, and better low-frequency performance is obtained.
The audio power amplifier module 120 is connected in series with the band elimination filter 110, and is configured to perform power amplification on the non-vibration audio signal output by the band elimination filter 110, so as to realize audio output in an external play scene.
According to the audio circuit provided by the embodiment of the invention, in an external scene, the band elimination filter 110 is adopted to replace a high-pass filter, so that the components of the motor vibration frequency in the original audio signal are filtered, the vibration-free audio signal output by the method can compensate the frequency near the motor resonance frequency point filtered by the traditional high-pass filter, part of low frequency is released, better low frequency performance is obtained, and the user experience is improved.
Based on any of the above embodiments, fig. 2 is a second schematic structural diagram of the audio circuit provided by the present invention, as shown in fig. 2, the audio circuit further includes a switch module 130 and an earpiece path module 140, where the switch module 130 is configured to transmit an original audio signal to the band elimination filter 110 in an external scene, and transmit the original audio signal to the earpiece path module 140 in an earpiece scene;
the earpiece path module 140 is used to implement audio output in an earpiece scene, and the earpiece path module 140 and the audio power amplifier module 120 are independent of each other.
In particular, the earpiece scene refers to a scene that is sounded with an earpiece in the terminal. Generally, the loudness of the sound emitted by the receiver is small, so that the receiver scene is suitable for sound playing in privacy scenes such as telephone answering.
The existing audio circuit only considers the voice call and multimedia playing scenes, but does not independently consider the earphone call scene, and in the earphone call scene, the original audio signal is still output through the audio power amplifier module 120. Because the radio frequency power supply pin and the audio power amplifier power supply pin are both battery powered, the receiver conversation can be influenced by a radio frequency GSM (global system for mobile communications) module TDMA (time Division multiple access), and more TDD (time Division) noises can be brought, so that the problems of receiver conversation interference sound and large bottom noise are caused, and the hearing is seriously influenced.
To address this problem, embodiments of the present invention add a switch module 130 and an earpiece path module 140 to the audio circuit. The switching module 130 is used to transmit the original audio signal to the band stop filter 110 in the play-out scene and to transmit the original audio signal to the earpiece path module 140 in the earpiece scene. The earpiece path module 140 is used to implement audio output in an earpiece scene, and the earpiece path module 140 and the audio power amplifier module 120 are independent of each other.
In one embodiment, the baseband chip outputs the original audio signal, and then the switching between the play-out scene and the earphone scene is completed through the switch module 130. In the play-out scene, the channel from the switch module 130 to the band-stop filter 110 is opened, the channel to the earpiece channel module 140 is closed, the original audio signal is transmitted to the band-stop filter 110, and the audio output in the play-out scene is realized through the audio power amplifier module 120.
In the earpiece scene, the channel from the switch module 130 to the band-stop filter 110 is closed, the channel to the earpiece path module 140 is opened, and the original audio signal is transmitted to the earpiece path module 140, so that the audio output in the earpiece scene is realized.
It should be noted that the earpiece access module 140 and the audio power amplifier module 120 are independent from each other, and in an earpiece scenario, an original audio signal does not pass through the audio power amplifier module 120, and radio frequency power supply and audio power amplifier power supply are independent from each other, thereby reducing circuit noise and radio frequency interference.
According to the audio circuit provided by the embodiment of the invention, the switching between the play-out scene and the receiver scene is completed through the switch module 130, and the receiver access module 140 and the audio power amplifier module 120 are mutually independent, so that in the receiver scene, an original audio signal does not pass through the audio power amplifier module 120, the radio frequency power supply and the audio power amplifier power supply are mutually independent, and the circuit noise and the radio frequency interference are reduced.
Based on the above embodiments, fig. 3 is a schematic circuit design diagram of the switch module 130 provided by the present invention, as shown in fig. 3:
the baseband chip outputs two paths of differential signals AU _ HSN and AU _ HSP of the original audio signal, and the switching between the play-out scene and the earphone conversation scene is completed through the switch module 130.
Under speaker playback scenes such as hands-free conversation, music playing and the like, the baseband chip of the mobile phone outputs differential audio signals AU _ HSN and AU _ HSP, and the signals are input to VIN pins of the switch module 130load switch chips U2 and U3. The baseband chip controls the loadswitch chip to complete the switching between the play-out scene and the receiver conversation scene through an enabling signal, namely an Enable signal. When playing the scene, Enable is 1 (high level), channels SPKN0 of the U2 chip and SPKP0 of the U3 chip are opened, output signals SPKN0 and SPKP0 flow into the audio power amplifier module 120 through the band elimination filter 110, and at this time, output pins RECN0 of the U2 chip and RECP0 of the U3 chip are closed. When the Enable is 0 (low level) in the handset call scene, the SPKN0 of the U2 chip and the SPKP0 of the U3 chip are turned off, and no signal is output. The RECN0 of the U2 chip and the RECP0 of the U3 chip are open, and the output signals RECN0 and RECP0 flow into the handset path module 140.
In any of the above embodiments, in the audio circuit, the earpiece path module 140 includes two differential path circuits, and two serially connected bias resistors; the two differential path circuits respectively carry out high-pass filtering and impedance matching on two paths of differential signals in the original audio signals;
two ends of the two serially connected bias resistors are respectively connected with the connection points of the serially connected capacitors and resistors in the two differential path circuits, and the connection point between the two serially connected bias resistors is connected with a bias voltage. Specifically, in the scenario of the handset, the original audio signal is transmitted to the handset access module 140 through the switch module 130, and the signal processed by the handset access module 140 is transmitted to the three-in-one speaker for output.
The earpiece in a triple-play speaker typically has an impedance, and the earpiece path module 140 may design an impedance matching circuit to eliminate the impedance mismatch problem. The bias resistor can avoid current leakage.
In one embodiment, fig. 4 is a schematic circuit diagram of the earpiece path module 140 provided by the present invention, as shown in fig. 4:
1) 2 12 omega resistors R13 in the handset path&R15 and a loudspeaker are connected in series to form an equivalent 32 omega load to simulate the internal resistance of a receiver, RREC＝R13+R15+RSPK. The power of the earphone access can be adjusted by changing the resistance value of the resistor. If the R13 and R15 resistances are increased, the handset outputsThe power is reduced; and when the resistance value is reduced, the output power of the receiver is increased.
2) In order to avoid the influence of the leakage current output from the audio power amplifier module 120 to the chip end earpiece pin on the earpiece circuit performance, 2 47uF capacitors C16 and C17 are required to be added for dc blocking, and at this time, a high pass filter is also formed with a 12 Ω resistor. Wherein R13 and C16 are high pass filters of N pole, and R15 and C17 are high pass filters of P pole. The N very high pass cutoff frequency fL is 1/(2 Π R13C 16) 282 Hz. If the capacitance value of C16 and the resistance value of R13 are increased, the value of fL is reduced; decreasing the capacitance of C13 and the resistance of R13 increases the value of fL. Similarly, the R15 and C17 parameter values for the P-high bandpass filter may be set.
3) To avoid leakage current, the DC voltage is established by biasing resistors R12, R14, and AVDD1V25 with a bias voltage of 1.25V, where R12-R14-1K Ω, which can eliminate the voltage difference.
According to the audio circuit provided by the embodiment of the invention, the receiver access module 140 is provided with the resistance-capacitance matching network to complete high-pass filtering and impedance matching, so that circuit noise and radio frequency interference are smaller, the receiver call quality is further improved, and the user experience is improved.
Based on any of the above embodiments, the audio circuit further includes a band-pass filter 150, where the band-pass filter 150 is configured to control the strength of the original motor signal and transmit the original motor signal to the audio power amplifier module 120, and the audio power amplifier module 120 is further configured to implement audio output in a vibration scene.
Specifically, the original signal output by the baseband chip platform has two paths, including an original audio signal and an original motor signal, where the original motor signal is used to implement motor vibration. In order to realize the output of different scenes, for example, in a scene only needing vibration, only the motor vibration signal is output, so that different signals need to be processed respectively.
The band pass filter 150 herein refers to a filter that can pass frequency components in the motor vibration frequency range, but attenuate frequency components in other ranges to an extremely low level, as opposed to the concept of the band stop filter 110. By adjusting parameters of components of the band pass filter 150, a frequency range in which an original motor signal can pass can be adjusted, thereby controlling the vibration intensity and comfort degree of the motor function.
The original motor signal is transmitted to the audio power amplifier module 120 through the band pass filter 150, and the audio power amplifier module 120 amplifies the power of the original motor signal, so that audio output in a vibration scene can be realized.
According to the audio circuit provided by the embodiment of the invention, the original motor signal is transmitted to the audio power amplification module 120 through the band-pass filter 150, so that the audio output in a vibration scene is realized.
Based on the above embodiments, fig. 5 is a schematic circuit design diagram of the bandpass filter 150 provided by the present invention, as shown in fig. 5:
in a motor vibration scenario, the baseband chip outputs a motor vibration signal PWM _ VIB, which is a 171Hz, 1.8V sine wave signal. The speaker based on trinity function embeds there is the vibration shell fragment, and resonant frequency is 171Hz 10Hz, by band pass filter 150 control motor vibration signal PWM _ VIB's size to the dynamics and the frequency of control shell fragment. As shown in fig. 5, the bandpass filter 150 in this embodiment is composed of R2, R3, C6, and C7, where R2 and C6 constitute a high-pass filter, and the 3dB low-frequency cutoff frequency fL1 is 1/(2 Π × R2 × C6) is 64 Hz. The resistance of R2 in this example was 2.5 KOHM. The capacity value of C6 is 1 uF. If the resistance value and the capacitance value are increased, the value of fL1 is reduced, and if the resistance value and the capacitance value are reduced, the value of fL1 is increased. Wherein, R3 and C7 form a low-pass filter, and the 3dB high-frequency cut-off frequency is fH1 ═ 1/(2 Π ═ R3 ═ C7) ═ 433 Hz. In this example, the resistance of R3 was 11KOHM and the capacitance of C7 was 33 nF. If the resistance value and the capacitance value are increased, the value of fL1 is reduced, and if the resistance value and the capacitance value are reduced, the value of fL1 is increased. By adjusting the values of R2, R3, C6 and C7, the vibration strength and comfort level of the motor function in specific application can be controlled.
Based on any of the above embodiments, in the audio circuit, the audio power amplifier module 120 includes an enabling end, and the audio power amplifier module 120 is configured to determine a current working scenario according to a waveform of an enabling signal received by the enabling end, and execute an operation corresponding to the current working scenario.
Specifically, the audio power amplifier module 120 may control the amplifier to be opened or closed by an enable signal received by the enable terminal. The high and low levels of the enable signal are configured, so that the enable signal pin can output different waveforms, the switching of the corresponding working scene is realized, the operation corresponding to the current working scene is executed, and the corresponding function is realized. The enable signal waveform may be a square wave with different rising edges, or may be a rectangular wave or a sawtooth wave, and the embodiment of the present invention is not particularly limited.
The current working scene herein may include a play-out scene, a vibration scene, and an earpiece scene, where the play-out scene may further include: a multimedia play scene or a voice call scene.
For example, when the enable signal is at a high level, a waveform with a rising edge is output, and at this time, the current working scene may be an external playing or vibration scene, the audio power amplifier module 120 is in an on mode, and the power amplifier performs an on operation; when the enable signal is always at a low level, a waveform without a rising edge is output, at this time, the current working scene is an earphone scene, the audio power amplifier module 120 is in a shutdown mode, and the power amplifier performs a shutdown operation.
Further, when the enable signal is at a high level, a music scene or a voice scene in the play-out scene may be determined according to different waveforms, for example, a rising edge waveform or a plurality of rising edge waveforms, and an operation corresponding to the current working scene may be performed.
It should be noted that the enabling signal waveforms may respectively correspond to different working scenes, and the corresponding relationship between the enabling signal waveforms and the working scenes may be one-to-one, or a plurality of enabling signal waveforms may correspond to one working scene, which is not specifically limited in this embodiment of the present invention.
Based on any of the above embodiments, in the audio circuit, if the current working scene is an external playing scene, the audio power amplification module 120 performs power amplification on the non-vibration-sensation audio signal;
if the current working scene is a vibration scene, the audio power amplification module 120 amplifies the power of the original motor signal;
if the current working scene is the receiver scene, the audio power amplifier module 120 is turned off.
Specifically, if the current working scene is an external scene, such as a multimedia playing scene or a hands-free voice call scene, the audio power amplifier module 120 performs power amplification on the non-vibration-sensation audio signal. The non-vibration audio signal is the audio signal of which the frequency near the motor resonance point is filtered by the original audio signal through the band stop filter 110, and more low-frequency signals are reserved, so that better low-frequency performance is obtained in a multimedia playing or hands-free voice call scene.
If the current working scene is a vibration scene, the audio power amplifier module 120 amplifies the power of the original motor signal, and the original motor signal can first pass through the band-pass filter 150 to control the strength and comfort degree of the motor vibration, and then is output through the audio power amplifier module 120 to realize the motor vibration function.
If the current working scene is the receiver scene, the audio power amplifier module 120 is turned off. Meanwhile, the switch module 130 switches to the earpiece scene, and the earpiece passage module 140 outputs the original audio signal in an audio mode.
In one embodiment, the enable signal is output by using GPIO of 2.8V, and the relationship between the waveform of the enable signal and the current working scenario can be shown in table 1 below: 1) when the enable signal is a rising edge square wave, the audio power amplification module 120 drives the speaker to realize the multimedia external playing function; 2) when the enabling signal is two rising edge square waves, the audio power amplification module 120 drives the loudspeaker to realize the voice call play-out function; 3) when the enabling signal is three rising edge square waves, the audio power amplification module 120 drives the loudspeaker to realize the motor vibration function; 4) when the enable signal is always at a low level, the audio power amplifier module 120 is in an off state, and the play mode is turned off. At this time, the earphone access output channel of the switch module 130 is opened to output the original audio signal, and then the three-in-one speaker is driven by the earphone access module 140 to realize the earphone call.
TABLE 1
According to the audio circuit provided by the embodiment of the invention, the current working scene is determined through the waveform of the enabling signal received by the enabling end, and the operation corresponding to the current working scene is executed, so that the function corresponding to the current working scene is realized. The voice signal, the multimedia signal and the motor vibration signal are processed respectively, so that the audio quality is improved, and the user experience is improved.
Based on the above embodiments, fig. 6 is a schematic circuit design diagram of the AUDIO power efficiency module provided by the present invention, and the AUDIO power efficiency module may further include an output end, as shown in fig. 6, the chip supplies power to the AUDIO power amplifier module 120 through a battery power supply signal (VBAT _ SPK), the amplifier is controlled to be turned on and turned off through an enable signal (AUDIO _ PA _ SDN), and two differential output pins VOUT1 and VOUT2 of the AUDIO power amplifier are respectively connected to the three-in-one speaker.
The input signals SPKN1 and SPKP1 are obtained by filtering the components of the motor vibration frequency from the original audio signals SPKN0 and SPKP0 by the band elimination filter 110. The band elimination filter 110 is directly connected with INN and INP pins of the audio power amplifier chip U1. The INP pin of the audio power amplifier chip U1 is also connected with the band-pass filter 150, the VDD pin is connected with the power line VBAT, the SD pin is connected with the enabling end, the Bypass pin is grounded through the C1 capacitor, the VOUT1 and the VOUT2 pin are connected with the output end, and the AGND pin of the audio power amplifier chip U1 is grounded.
Based on any of the above embodiments, in the audio circuit, the band-stop filter 110 includes two differential band-stop filters, and the two differential band-stop filters perform band-stop filtering on two paths of differential signals in the original audio signal, respectively.
Specifically, the band-elimination filter 110 is used for filtering out components of the motor vibration frequency in the original audio signal in the play-out scene. Here, the original audio signal may include two differential signals, where the two differential signals have equal amplitudes and opposite phases. Accordingly, the band-stop filter 110 may include two differential band-stop filters that respectively perform band-stop filtering on two differential signals in the original audio signal. Here, the circuit design of the two differential band reject filters is the same.
Based on any of the above embodiments, the differential band rejection filter comprises a second-order low pass filter and a second-order high pass filter connected in parallel.
Specifically, any one of the differential band rejection filters may include a second-order low-pass filter and a second-order high-pass filter, wherein the second-order low-pass filter and the second-order high-pass filter are connected in parallel. It should be noted that the number of the second-order low-pass filters and the second-order high-pass filters is the same.
Based on any of the above embodiments, fig. 7 is a schematic circuit design diagram of the band elimination filter 110 provided by the present invention, and as shown in fig. 7, the original audio signal includes two paths of differential signals SPKN0 and SPKP0, which are respectively subjected to band elimination filtering by the differential band elimination filter to output vibration-free audio signals SPKN1 and SPKP 1.
The second-order low-pass filter comprises a first resistor, a second resistor, a first capacitor and a second capacitor, wherein the first resistor and the second resistor are connected in series; the second-order high-pass filter comprises a third resistor, a fourth resistor, a third capacitor and a fourth capacitor, the third capacitor is connected with the fourth capacitor in series, the third resistor is connected with the fourth resistor in parallel, one end of the third resistor is connected with a connection point of the third capacitor and the fourth capacitor, and the other end of the third resistor is grounded.
Referring to fig. 7, a differential band-stop filter for performing band-stop filtering on one path of differential signals is composed of R4, R5, C8, C9, R6, R7, C10 and C11, and a differential band-stop filter for performing band-stop filtering on the other path of differential signals is composed of R8, R9, C12, C13, R10, R11, C14 and C15.
Any differential band-stop filter can be formed by connecting a second-order high-pass filter and a second-order low-pass filter in parallel. The center frequency of the differential band elimination filter is fc, and fc is designed to be close to the motor resonant voltage through resistance-capacitance combination. And the Q value can be adjusted, the stop band of the differential band elimination filter is superposed with the frequency of the pass band of the motor vibration, the motor vibration is accurately and effectively filtered, and other low-frequency components are reserved, so that the low-frequency feeling is improved.
For example, one of the differential band-stop filters is a second-order low-pass filter composed of R4, R5, C8 and C9, and R6, R7, C10,And the second-order high-pass filter formed by C11 is connected in parallel. Stop band omegacl＜ω＜ωchSo that it can attenuate ωclTo omegachAnd (c) a signal.
Wherein, ω isclAnd ωchUpper and lower cut-off frequencies, Q, respectively, of a differential band-stop filterpIs a polar couple quality factor, omegapIs the pole frequency, ω0Is the center frequency of the differential band reject filter.
When R4 ═ R6 ═ R, R5 ═ R7 ═ 10 ═ R, C8 ═ C10 ═ C, C9 ═ C11 ═ 1/10 ═ C, ω C, and ω0＝1/RC，fc＝ω0/2Π。
The stopband width B of the differential bandstop filter is:
a quality factor Q of
Can dynamically adjust omega according to the resonance bandwidth of the three-in-one loudspeakerclAnd ωchAnd different Q values are obtained, so that the optimal filtering effect is obtained. The calculation can obtain: r4 ═ R6 ═ R100 ohm, R5 ═ R7 ═ R1 kohm, C8 ═ C10 ═ C ═ 10uF, C9 ═ C11 ═ 1/10 ═ C ═ 1 uF. Omegacl＝64.7Hz，ωch＝433.64Hz，fc＝171Hz，Q＝0.46。
Similarly, the setting of the resistance and capacitance of the other differential band-stop filter for filtering the other path of differential signal is the same as that described above, and is not described again.
According to the audio circuit provided by the embodiment of the invention, the frequency of the stop band of the band elimination filter 110 is superposed with the frequency of the pass band of the motor vibration by adjusting the quality factor Q value of the band elimination filter 110, so that the motor vibration sense is accurately and effectively filtered, and other low-frequency components are reserved, thereby improving the low-frequency feeling.
Based on any of the above embodiments, fig. 8 is a schematic structural diagram of the audio device provided in the present invention, as shown in fig. 8, the audio device includes an audio circuit and a three-in-one speaker 160, and the three-in-one speaker 160 is connected to an output terminal of an audio power amplifier module in the audio circuit.
Specifically, the three-in-one speaker 160 herein refers to a combination of a speaker, an earpiece and a motor, and the model of the three-in-one speaker 160 is not particularly limited, and may be any model of three-in-one speaker.
The audio device can realize the switching between the play-out scene and the receiver call scene through the control of the switch module 130 in the audio circuit, and the circuit design of the play-out scene and the receiver call scene are mutually independent.
In the play-out scene, the audio power amplifier module 120 may implement switching between the multimedia playing and hands-free calling modes; meanwhile, in the play-out scene, the band-stop filter 110 is used for replacing a traditional high-pass filter, only audio signals with frequencies near a motor resonance point in the original audio signals are filtered, more low-frequency signals are reserved, loss of the low-frequency signals is reduced, better low-frequency performance is obtained, and therefore user experience is improved. The audio power amplifier module 120 amplifies the power of the original audio signal and outputs the amplified audio signal through the three-in-one speaker 160.
Under the earphone scene, the output of the earphone access module 140 in trinity speaker 160 and the audio circuit is connected, and original audio signal does not pass through the power amplifier, directly transmits to the earphone access module 140, and the output of the trinity speaker 160 of rethread. High-pass filtering and impedance matching are accomplished through the rc matching network in the earpiece pass-through module 140, resulting in less circuit noise and radio frequency interference.
In a vibration scene, the original motor signal is first filtered 150 by the band-pass filter, then power-amplified by the audio power amplifier module 120, and finally output by the three-in-one speaker 160.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. An audio circuit, comprising:
the band elimination filter and the audio power amplification module are connected in series;
the band elimination filter is used for filtering components of motor vibration frequency in an original audio signal in an external scene and outputting a vibration-free audio signal to the audio power amplification module, and the audio power amplification module is used for realizing audio output in the external scene.
2. The audio circuit of claim 1, further comprising: a switch module and an earphone access module;
the switch module is used for transmitting the original audio signal to the band elimination filter in the play-out scene and transmitting the original audio signal to the earphone access module in the earphone scene;
the receiver access module is used for realizing audio output in the receiver scene, and the receiver access module and the audio power amplifier module are mutually independent.
3. The audio circuit of claim 2, wherein the earpiece path module comprises two differential path circuits, and two serially connected bias resistors; the two differential path circuits respectively perform high-pass filtering and impedance matching on two paths of differential signals in the original audio signals;
two ends of the two serially connected bias resistors are respectively connected with connection points of the serially connected capacitors and resistors in the two differential path circuits, and a connection point between the two serially connected bias resistors is connected with a bias voltage.
4. The audio circuit of claim 1, further comprising a band-pass filter, wherein the band-pass filter is configured to control the strength of an original motor signal and transmit the original motor signal to the audio power amplifier module, and the audio power amplifier module is further configured to implement audio output in a vibration scene.
5. The audio circuit according to claim 1, wherein the audio power amplifier module includes an enable terminal, and the audio power amplifier module is configured to determine a current working scenario according to a waveform of an enable signal received by the enable terminal, and execute an operation corresponding to the current working scenario.
6. The audio circuit according to claim 5, wherein if the current working scene is a play-out scene, the audio power amplifier module performs power amplification on the non-vibration-sensation audio signal;
if the current working scene is a vibration scene, the audio power amplification module amplifies the power of the original motor signal;
and if the current working scene is a receiver scene, the audio power amplification module is turned off.
7. The audio circuit according to any of claims 1-6, wherein the band-stop filter comprises two differential band-stop filters that respectively band-stop two paths of differential signals in the original audio signal.
8. The audio circuit of claim 7, wherein the differential band reject filter comprises a second order low pass filter and a second order high pass filter connected in parallel.
9. The audio circuit according to claim 8, wherein the second order low pass filter includes a first resistor and a second resistor connected in series, and a first capacitor and a second capacitor connected in parallel, one end of the first capacitor is connected to a connection point of the first resistor and the second resistor, and the other end of the first capacitor is grounded;
the second-order high-pass filter comprises a third resistor, a fourth resistor, a third capacitor and a fourth capacitor, the third capacitor is connected with the fourth capacitor in series, the third resistor is connected with the fourth resistor in parallel, one end of the third resistor is connected with a connection point of the third capacitor and the fourth capacitor, and the other end of the third resistor is grounded.
10. An audio device, comprising the audio circuit of any one of claims 1-9, and a three-in-one speaker, wherein the three-in-one speaker is connected to the output terminal of the audio power amplifier module in the audio circuit of any one of claims 1-9.
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