CN211089941U - Gain switching noise reduction circuit and audio device thereof - Google Patents
Gain switching noise reduction circuit and audio device thereof Download PDFInfo
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- CN211089941U CN211089941U CN202020428628.2U CN202020428628U CN211089941U CN 211089941 U CN211089941 U CN 211089941U CN 202020428628 U CN202020428628 U CN 202020428628U CN 211089941 U CN211089941 U CN 211089941U
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Abstract
The utility model provides a gain switches and falls circuit of making an uproar and audio device thereof should fall the circuit of making an uproar and fall the outside amplifier circuit of making an uproar circuit connection and fall, through calculating the calibration value to in falling the circuit of making an uproar with it, at the chip during operation, calibrate the output signal of leading circuit according to the calibration value, offset the gain influence brought by circuit offset voltage, eliminate the level jump, realize falling the purpose of making an uproar.
Description
Technical Field
The utility model relates to an integrated circuit audio circuit field, concretely relates to gain switches and falls circuit of making an uproar and audio device thereof.
Background
The earphone is a pair of conversion units which receive the electric signals sent by the media player or receiver and convert the electric signals into audible sound waves by using a loudspeaker close to the ear. The headset is typically detachable from the media player and utilizes a plug connection. The earphone is originally used for telephone and radio, but with the prevalence of portable electronic devices, the earphone is mostly used for mobile phones, walkmans, radios, portable electronic games, audio players, and the like.
With the advancement of science and technology and the increase of modern life requirements of people, bluetooth TWS (True Wireless stereo) earphones are widely favored because they get rid of a connecting wire connected from a player to an earphone body. TWS bluetooth headset is worn when being particularly suitable for carrying out motion or other activities, can reduce the trouble that the line body winding brought, and is very convenient.
An audio differential operational amplifier module in the existing TWS Bluetooth headset chip has an input offset voltage V at the input end of the operational amplifier due to the difference of manufacturing processesos(Input offset Voltage), resulting in V of the outputoffset＝Vout+-Vout-The voltage has a certain voltage difference.
When the operational amplifier circuit is used in the chip, the output V is caused by the existence of input offset voltageDACLAnd VDACL#There is a certain pressure difference, when the music stops playing, such as pause, up/down switching, other audio switching-in, etc., the operational amplifier gain is minimum, i.e. Rf0 ohm, V at this timeoffset1Is approximately equal to the input offset voltage Vos(ii) a When playing music, R when the operational amplifier has larger gainfWill have a certain resistance value, Voffset2A voltage of AV*(VIN+-VIN-)＝AV*Vos，AvFor this time the operational amplifier gain, i.e. offset voltage VosAnd is also amplified following the op-amp gain.
When stopping and playing, the operational amplifier minimum gain bias voltage Voffset1With a larger gain bias voltage Voffset2Bias value V ofoffset＝|Voffset1–Voffset2I is not uniform, V is a difference according to semiconductor manufacturing processoffsetThe value of (b) may be about 1 to 30 mV. Because the switching between playing and stopping has a jump of DC level, the bias voltage of differential output is not at the same level in the process from playing to stopping, which results in the condition of noise, and the sensitivity of earphoneThis noise is heard well.
SUMMERY OF THE UTILITY MODEL
Based on the technical problem, the utility model provides a gain switches and falls circuit of making an uproar and audio device thereof can eliminate the audio frequency fortune and put the noise problem that leads to when minimum gain switches with great gain, realizes falling the function of making an uproar.
The technical scheme of the utility model is realized by following content:
in a first aspect, the present invention provides a gain switching noise reduction circuit, comprising a pre-circuit, an operational amplifier circuit and a control circuit, wherein,
the operational amplifier circuit comprises a primary amplifier circuit and a secondary amplifier circuit;
the pre-circuit is connected with the control circuit, and the output end of the pre-circuit is connected with the input end of the primary amplifying circuit;
the output end of the first-stage amplifying circuit is connected with the input end of the second-stage amplifying circuit, and the output end of the first-stage amplifying circuit outputs a high-potential signal of the noise reduction circuit;
the second-stage amplifying circuit outputs a low potential signal of the noise reduction circuit;
the control circuit is respectively connected with the front-end circuit and the primary amplifying circuit and is used for controlling the signal output of the front-end circuit and the gain of the primary amplifying circuit.
Specifically, the output end of the pre-circuit is connected with the inverting input end of the first-stage amplifying circuit.
Specifically, the output end of the primary amplification circuit is connected with the inverting input end of the secondary amplification circuit.
Specifically, the non-inverting input terminal of the first-stage amplifying circuit is grounded, and the non-inverting input terminal of the second-stage amplifying circuit is grounded.
Specifically, the control circuit calibrates the signal output of the front-end circuit.
Specifically, the control circuit calibrates the output signal of the front-end circuit according to the offset voltage of the primary amplification circuit.
In a second aspect, the utility model provides an use above-mentioned audio device who falls circuit of making an uproar.
Specifically, the audio device comprises a main ear and an auxiliary ear, and the main ear is connected with the auxiliary ear through Bluetooth.
The utility model provides a gain switches and falls circuit of making an uproar and audio device thereof is through calculating the calibration value to in falling the circuit of making an uproar with it write in, at the chip during operation, calibrate the output signal of leading circuit according to the calibration value, offset the gain influence brought by circuit offset voltage, eliminate the level jump, realize falling the purpose of making an uproar.
Drawings
Fig. 1 is a circuit structure diagram of an audio differential operational amplifier module in a TWS headset according to the prior art.
Fig. 2 is a circuit block diagram of a gain switching noise reduction circuit according to an embodiment of the present invention.
Fig. 3 is a specific circuit structure diagram of the gain switching noise reduction circuit according to an embodiment of the present invention.
Fig. 4 is a flowchart of steps of a noise reduction method according to an embodiment of the present invention.
Fig. 5 is a circuit block diagram of an implementation of the noise reduction method according to the second embodiment of the present invention.
Fig. 6 is an equivalent circuit diagram of a specific circuit structure in the first embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Thus, the following detailed description of the embodiments of the present invention, presented in the accompanying drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiment of the present invention, all other embodiments obtained by the person skilled in the art without creative work belong to the protection scope of the present invention.
The first embodiment is as follows:
in one embodiment, a gain switching noise reduction circuit is provided, as shown in fig. 2, the noise reduction circuit includes a pre-circuit, an operational amplifier circuit and a control circuit, wherein,
the operational amplifier circuit comprises a primary amplifier circuit and a secondary amplifier circuit;
the pre-circuit is connected with the control circuit, and the output end of the pre-circuit is connected with the input end of the primary amplifying circuit;
the output end of the first-stage amplifying circuit is connected with the input end of the second-stage amplifying circuit, and the output end of the first-stage amplifying circuit outputs a high-potential signal of the noise reduction circuit;
the second-stage amplifying circuit outputs a low potential signal of the noise reduction circuit;
the control circuit is respectively connected with the front-end circuit and the primary amplifying circuit and is used for controlling the signal output of the front-end circuit and the gain of the primary amplifying circuit.
As a specific implementation manner of this embodiment, referring to fig. 3, it shows a structure diagram of an operational amplifier circuit in the specific implementation manner of this embodiment, as shown in the figure, a left-side primary amplification circuit in the figure includes a primary amplifier AMP1 and an adjustable resistor RxAnd RyA switch METU, wherein the front-end circuit shown in FIG. 2 inputs a signal VinThe input voltage is the inverting input terminal of a primary amplifier AMP1, the non-inverting input terminal of the primary amplifier AMP is grounded, and an adjustable resistor RxAnd RyThe gain of the first-stage amplifying circuit is controlled, and the switch METU controls the adjustable resistor RyThe connection and disconnection of the mobile terminal; the right-side secondary amplification circuit is a classical inverting amplification circuit and comprises a secondary amplifier AMP2 and a resistor R1And R2The output end of the primary amplifier AMP1 is connected to the inverting input end of the secondary amplifier AMP2, and the non-inverting input end of the secondary amplifier AMP2 is grounded.
As a specific implementation manner of this embodiment, the control circuit calibrates the output signal of the front-end circuit according to the offset voltage of the primary amplifying circuit, so as to eliminate the level jump and achieve the purpose of noise reduction, and the specific calibration manner and calibration size are detailed in the following second embodiment.
Example two:
the second embodiment provides a noise reduction method using the noise reduction circuit, which utilizes the noise reduction circuit of the first embodiment and an external amplification circuit connected to the noise reduction circuit to perform noise reduction, and referring to fig. 4, it shows specific steps of the noise reduction method:
s101, enabling the operational amplifier circuit to be in a working state, and minimizing the gain of the operational amplifier circuit;
s102, the control circuit collects and records the amplified first signal;
s103, adjusting the gain of the operational amplifier circuit, and collecting the amplified second signal by the control circuit;
s104, adjusting a calibration value according to the first signal and the second signal;
and S105, writing the obtained calibration value into the control circuit.
The first signal is a first signal which is output by the operational amplifier circuit in a gain minimized state and is amplified by the external amplifier circuit and collected by the control circuit; the second signal is output by the operational amplifier circuit under a certain gain state, amplified by the external amplifier circuit and collected by the control circuit.
Referring to fig. 5, which shows a circuit diagram for implementing the above noise reduction method, the noise reduction circuit is disposed inside the integrated circuit chip, and after the output signal of the noise reduction circuit is amplified by the external amplifying circuit, the output signal is collected and calculated by the control circuit, so as to obtain the offset voltage calibration value of the front-end circuit.
As an example of the above method, in the first embodiment, in the specific implementation of the circuit structure diagram shown in fig. 3, the equivalent circuit diagram is shown in fig. 6, in which V is shownos1Is the offset voltage, V, of the first-stage amplifier AMP1os2For the offset voltage of the two-stage amplifier AMP2, the calibration value is calculated according to the equivalent circuit diagram as follows:
adjustable resistance R when enabling METU switchingyIs cut off, the gain of the operational amplifier circuit is minimized, and the output is the offset voltage V of the whole operational amplifier circuitoffset1And is specifically Voffset1＝Vout+-Vout-According to the virtual short and virtual break characteristics of the amplifier,
(VDC–Vos1)/Rx＝(Vos1–Vos2)/R1＝(Vos2–Vout-)/R2
wherein, VDCThe offset voltage V can be obtained according to the formula under the condition of no gain for the output signal before the pre-circuit is not calibratedoffset1＝Vout+-Vout-＝2Vos1–2Vos2Acquiring a first signal V of an external amplifying circuit through a control circuitAD1＝G2*Voffset1Wherein G is2Is the gain factor of the external amplifying circuit.
Collecting a first signal V at a control circuitAD1After that, it is recorded in the control circuit.
Adjustable resistance R when the METU switch is turned offyThe access circuit and the operational amplifier circuit gain the input signal, and the gain can be adjusted through the adjustable resistor RxAnd RyRegulating, operating and amplifying circuit output bias voltage Voffset2＝Vout+-Vout-According to the virtual short and virtual break characteristics of the amplifier,
(Vtrim–Vos1)/Rx＝(Vos1–Vout+)/Ry＝(Vos1–Vos2)/(Ry+R1)＝(Vos2–Vout-)/R2
wherein, VtrimFor the calibration value, let Ry/Rx＝G1I.e. gain multiple of the primary amplifier AMP1 is G1According to the formula, the bias voltage V output by the operational amplifier circuit in the gain state can be obtainedoffset2＝2Vtrim*(-G1)+2Vos1*(1+G1)-2Vos2＝2G1*(Vos1-Vtrim)+2Vos1-2Vos。
Thus, the second signal V of the external amplification circuit is picked up by the control circuitAD2Time of second signal VAD2＝G2*[2G1*(Vos1-Vtrim)+2Vos1-2Vos2]。
The purpose of this embodiment is to output signal V in the gain stateoffsetIndependent of offset voltage, it is equivalent to no gain V for external amplifier circuitAD1Is equal to V with gainAD2This will eliminate the offset voltage VosFollowing the effect of the gain of the operational amplifier circuit, it follows thatAD1＝VAD2，G2*Voffset1＝G2*[2G1*(Vos1-Vtrim)+2Vos1-2Vos2]，G2*Voffset1＝G2*[2G1*(Vos1-Vtrim)+Voffset1]，G2*2G1*(Vos1-Vtrim) When V is 0, it can be concluded thattrim＝Vos1At times, the second signal V is independent of the gain of the operational amplifier circuitAD2Will not change with the gain, so that the offset voltage V can be adjusted when the gain is switchedosThe gain of the operational amplifier circuit is not followed, the level jump caused by the bias voltage not being on the same level during the gain switching is eliminated, and the purpose of noise reduction is achieved.
Therefore, based on the above calibration value calculation, in the above step S104, the calibration value V is calculatedtrimIs equal to the offset voltage V of the first-stage amplifying circuitos1. And offset voltage Vos1Due to differences in semiconductor manufacturing processes, the offset voltage V of each amplifieros1Are all unfixed, so that the calibration value can be adjusted only by inputting for multiple times, and the control circuit acquires the second signal V for multiple timesAD2Order the second signal V collectedAD2Is equal to the first signal VAD1And finally, writing the final calibration value into the chip control circuit firmware.
Returning to the circuit structure diagrams shown in fig. 2 and fig. 3, after the specific calibration value is obtained by multiple adjustments, the front-end circuit outputs the signal V in the working state of the noise reduction circuitDCBefore, the control circuit inputs the calibration value into the front-end circuit for calibration, so as to makeThe actual output signal of the front-end circuit is VDC+VtrimAfter the output signal is calibrated, offset voltage caused by difference of a semiconductor manufacturing process is offset, and the influence of the offset voltage after following the gain of the input signal is eliminated, so that the problem of level jump does not occur during gain switching, and the purpose of noise reduction is achieved.
Example three:
as an example, the audio device is the TWS bluetooth headset in the background art, and includes a main ear and an auxiliary ear, where chips in the main ear and the auxiliary ear are both provided with the noise reduction circuit, before the TWS bluetooth headset leaves a factory, a calibration value is written into the control circuit by the noise reduction method, and when the TWS bluetooth headset normally works, a voltage signal output by the front-end circuit is calibrated by the calibration value, so that noise caused by an offset voltage of an amplifier during switching of operational amplifier gains is eliminated, and a purpose of reducing noise is achieved. The specific noise reduction principle and implementation process refer to those described in the second embodiment, which are not described herein in detail.
The main ear and the auxiliary ear are connected in a bluetooth pairing mode, preferably connected in B L E mode, and for the pairing, connection, audio playing and other operations of the bluetooth headset, reference may be made to the existing technology of TWS headsets, and this embodiment is not specifically described here.
It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention, and those skilled in the art can make various modifications and changes. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. A gain switching noise reduction circuit is characterized by comprising a front-end circuit, an operational amplifier circuit and a control circuit,
the operational amplifier circuit comprises a primary amplifier circuit and a secondary amplifier circuit;
the pre-circuit is connected with the control circuit, and the output end of the pre-circuit is connected with the input end of the primary amplifying circuit;
the output end of the first-stage amplifying circuit is connected with the input end of the second-stage amplifying circuit, and the output end of the first-stage amplifying circuit outputs a high-potential signal of the noise reduction circuit;
the second-stage amplifying circuit outputs a low potential signal of the noise reduction circuit;
the control circuit is respectively connected with the front-end circuit and the primary amplifying circuit and is used for controlling the signal output of the front-end circuit and the gain of the primary amplifying circuit.
2. The noise reduction circuit according to claim 1, wherein an output terminal of the pre-stage circuit is connected to an inverting input terminal of the one-stage amplification circuit.
3. The noise reduction circuit according to claim 1, wherein an output terminal of the primary amplification circuit is connected to an inverting input terminal of the secondary amplification circuit.
4. The noise reduction circuit according to claim 1, wherein a non-inverting input terminal of the primary amplification circuit is grounded, and a non-inverting input terminal of the secondary amplification circuit is grounded.
5. The noise reduction circuit according to any of claims 1-4, wherein the control circuit calibrates the signal output of the pre-circuit.
6. The noise reduction circuit according to claim 5, wherein the control circuit calibrates the output signal of the pre-stage circuit according to an offset voltage of the first-stage amplification circuit.
7. An audio device using the noise reduction circuit according to any one of claims 1 to 6.
8. The audio device of claim 7, wherein the audio device comprises a primary ear and a secondary ear, the primary ear and the secondary ear being connected via Bluetooth.
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| CN202020428628.2U CN211089941U (en) | 2020-03-27 | 2020-03-27 | Gain switching noise reduction circuit and audio device thereof |
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| CN202020428628.2U CN211089941U (en) | 2020-03-27 | 2020-03-27 | Gain switching noise reduction circuit and audio device thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111263271A (en) * | 2020-03-27 | 2020-06-09 | 深圳市中科蓝讯科技股份有限公司 | Gain switching noise reduction circuit, noise reduction method thereof and audio device |
| CN112601159A (en) * | 2020-12-10 | 2021-04-02 | 深圳市中科蓝讯科技股份有限公司 | Audio calibration circuit and audio equipment |
-
2020
- 2020-03-27 CN CN202020428628.2U patent/CN211089941U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111263271A (en) * | 2020-03-27 | 2020-06-09 | 深圳市中科蓝讯科技股份有限公司 | Gain switching noise reduction circuit, noise reduction method thereof and audio device |
| CN112601159A (en) * | 2020-12-10 | 2021-04-02 | 深圳市中科蓝讯科技股份有限公司 | Audio calibration circuit and audio equipment |
| CN112601159B (en) * | 2020-12-10 | 2022-03-15 | 深圳市中科蓝讯科技股份有限公司 | Audio calibration circuit and audio equipment |
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