Wireless audio transmission and emission circuit

Abstract

The utility model discloses a wireless audio transmission and emission circuit, which comprises an active amplifier, resistors and capacitors, the active amplifier, the plurality of resistors and the plurality of capacitors form an active emphasis circuit, and the active emphasis circuit is used for dividing an input passband audio signal into a plurality of frequency regions. Negative feedback of different depths is adopted for the audio signals of different frequency regions, so that the amplification times of the audio signals of different frequency regions are controlled, and high frequency in the audio signals in a transmission band is increased; the active emphasis circuit is an in-phase amplification active emphasis circuit, and the in-phase amplification active emphasis circuit comprises a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first capacitor C1, a second capacitor C2 and a third capacitor C3; the active emphasis circuit is a reverse-phase amplification active emphasis circuit, and the reverse-phase amplification active emphasis circuit comprises a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first capacitor C1 and a second capacitor C2.

Description

Technical Field

[0001] The utility model relates to the technical field of audio transmission, and in particular to a wireless audio transmission transmitting circuit for improving audio quality. Background Art

[0002] In the design of wireless audio transmission circuit structure, in order to reduce the RF (Radio Frequency) transmission noise, the high frequency of the audio signal before modulation of the transmitting circuit must be pre-emphasized, and the receiving circuit must de-emphasize the audio signal after demodulation. At present, the pre-emphasis circuit design in wireless audio transmission transmitting circuits at home and abroad all adopts simple RC parallel circuits or passive RC differential circuits. RC parallel circuits and RC differential circuits can solve the attenuation of low frequencies within the passband, that is, high-frequency emphasis, but there are also many problems, which deteriorate the sound quality of the transmitted audio. Existing RC parallel circuits such as Figure 1 As shown in the figure, resistor R1' is connected in series with resistor R2' and then connected in parallel with capacitor C1'. The RC parallel circuit will cause the transmission sound quality to deteriorate due to the following reasons:

[0003] The impedance of the RC parallel audio pre-emphasis circuit changes with the input signal frequency. Figure 1 When the input signal is low frequency, C1' is in an open circuit state, and the impedance R = R1' + R2'. When the input signal is high frequency, C1' is in a short circuit state, and the impedance R = R1'. When the input signal is medium frequency, the impedance R = R1' + R2' × C1's capacitive reactance / R2' + C1' capacitive reactance. This impedance fluctuates with the frequency, which damages the sound quality. The amplified high-frequency signal in the RC parallel circuit is output after passing through C1', and the charging and discharging time constant of C1' affects the time domain characteristics of the audio. In the RC parallel circuit, the voltage of the high-frequency signal passing through C1' lags and the current leads, which produces a relative phase shift with the low-frequency signal passing through R2'. When the phases of the frequency zones of the audio signal in a passband are inconsistent, it is inevitable that the sound quality will deteriorate. Summary of the invention

[0004] The purpose of the utility model is to solve the problem of impedance fluctuation, time constant and phase shift in RC parallel circuit and RC differential circuit that damage the sound quality, and to provide a wireless audio transmission transmitting circuit, which not only achieves the purpose of pre-emphasis, but also overcomes the three major defects of impedance fluctuation, time constant and phase shift.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0006] A wireless audio transmission transmitting circuit comprises an active amplifier, a resistor and a capacitor. The active amplifier, a plurality of resistors and a plurality of capacitors form an active emphasis circuit. The active emphasis circuit is used to divide an input passband audio signal into a plurality of frequency regions, and adopt negative feedback of different depths for audio signals in different frequency regions to control the amplification factors of audio signals in different frequency regions, so as to obtain the emphasis on the high frequency of the audio signal in the passband.

[0007] The active emphasis circuit is a common-phase amplification active emphasis circuit, which at least includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first capacitor C1, a second capacitor C2 and a third capacitor C3;

[0008] The first end of the active amplifier is connected to the input end of the transmitting circuit, the first resistor R1 is connected in parallel with the first capacitor C1, the third resistor R3 and the second capacitor C2 are connected in series and then connected in parallel with the second resistor R2, and the fourth resistor R4 and the third capacitor C3 are connected in series and then connected in parallel with the second resistor R2;

[0009] The first end of the first resistor R1, the first end of the first capacitor C1, the second end of the second resistor R2, the second end of the third resistor R3, and the second end of the fourth resistor R4 are respectively connected to the second end of the active amplifier, the second end of the first resistor R1, the second end of the first capacitor C1, and the third end of the active amplifier are respectively connected to the output end of the transmitting circuit, and the first end of the second resistor R2, the first end of the second capacitor C2, and the first end of the third capacitor C3 are respectively grounded;

[0010] Or the active emphasis circuit is an inverting amplifying active emphasis circuit, which at least includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first capacitor C1 and a second capacitor C2;

[0011] The first end of the active amplifier is grounded, the first end of the first resistor R1 is connected to the input end of the transmitting circuit, and the second end of the first resistor R1 and the first end of the second resistor R2 are respectively connected to the second end of the active amplifier;

[0012] The first end of the third resistor R3, the first end of the fourth resistor R4, and the first end of the fifth resistor R5 are respectively connected to the second end of the second resistor R2, the fourth resistor R4 and the first capacitor C1 are connected in series, the fifth resistor R5 and the second capacitor C2 are connected in series, the second end of the third resistor R3 and the third end of the active amplifier are respectively connected to the output end of the transmitting circuit, the second end of the first capacitor C1 and the second end of the second capacitor C2 are respectively grounded

[0013] Furthermore, the active amplifier is any one of an operational amplifier, a line amplifier, and a triode.

[0014] Furthermore, an operational amplifier in-phase amplification active emphasis circuit is used, the second resistor R2 is used to control the attenuation of the full frequency band relative to the mid-high frequency and high frequency bands, the second capacitor C2 is used to separate the mid-high frequency band from the full frequency band, and the third capacitor C3 is used to separate the high frequency band from the full frequency band.

[0015] Furthermore, the in-phase amplification active emphasis circuit is used to divide the audio signal within the passband into multiple frequency zones, including at least three frequency zones of R2, R3+C2, and R4+C3, and control the audio signals in different frequency zones with different amplification factors to obtain emphasis on the high frequencies of the audio signal within the passband.

[0016] Furthermore, the in-phase amplifier active emphasis circuit is used to control the gain of different audio frequency bands by adopting different negative feedback depths. The first resistor R1 is a negative feedback resistor, the first capacitor C1 is a negative feedback capacitor, and the second resistor R2>the third resistor R3>the fourth resistor R4.

[0017] Furthermore, the first resistor R1 and the second resistor R2 are used to determine the bandwidth and amplification factor of the low frequency band within the passband; the first resistor R1, the third resistor R3 and the second capacitor C2 are used to determine the bandwidth and amplification factor of the medium and high frequency bands; the first resistor R1, the fourth resistor R4 and the third capacitor C3 are used to determine the bandwidth and amplification factor of the high frequency band.

[0018] Furthermore, by using the operational amplifier's in-phase amplification active emphasis circuit, the full-band amplification factor = (R1 / R2) + 1; under the condition of ignoring the capacitive reactance of the capacitor, the amplification factor of the mid-high frequency band = (R1 / R3) + 1; the amplification factor of the high frequency band = (R1 / R4) + 1.

[0019] Furthermore, an inverting amplification active emphasis circuit of an operational amplifier is adopted, the second resistor R2 and the third resistor R3 are used to control the attenuation of the full frequency band relative to the mid-high frequency band and the high frequency band, the first capacitor C1 is used to separate the mid-high frequency band from the full frequency band, and the second capacitor C2 is used to separate the high frequency band from the full frequency band.

[0020] Furthermore, the inverting amplifier active emphasis circuit is used to divide the audio signal in the passband into multiple frequency zones, including at least three frequency zones of R1+R2+R3, R4+C1, and R5+C2, to control the amplification factors of the audio signals in different frequency zones, and to obtain the emphasis of the high-frequency signal in the passband.

[0021] Furthermore, the first resistor R1, the second resistor R2 and the third resistor R3 are used to determine the bandwidth and amplification factor of the low frequency band in the passband; the fourth resistor R4 and the first capacitor C1 are used to determine the bandwidth and amplification factor of the medium and high frequency bands; the fifth resistor R5 and the second capacitor C2 are used to determine the bandwidth and amplification factor of the high frequency band.

[0022] Compared with the prior art, the utility model forms an active emphasis circuit by providing an active amplifier, and the active amplifier and multiple resistors and multiple capacitors divide the input passband audio signal into multiple frequency zones to control the amplification factors of audio signals in different frequency zones, thereby obtaining the emphasis on the high frequencies of the audio signal in the passband, realizing the "emphasis" between audio signal partitions, solving the frequency division in the passband and the independent amplification of different frequency zones, and realizing lossless audio emphasis. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of an RC parallel circuit in the prior art.

[0024] Figure 2 Schematic diagram of a common-mode amplification active emphasis circuit using an operational amplifier according to Embodiment 1.

[0025] Figure 3 This is a schematic diagram of an inverting amplification active emphasis circuit using an operational amplifier according to Embodiment 2. DETAILED DESCRIPTION

[0026] The wireless audio transmission transmitting circuit of the present utility model is further described below in conjunction with the accompanying drawings and specific embodiments.

[0027] Example 1

[0028] The utility model discloses a wireless audio transmission transmitting circuit, comprising an active amplifier, a resistor and a capacitor, wherein the active amplifier and a plurality of resistors and a plurality of capacitors form an active emphasis circuit, wherein the active amplifier is an operational amplifier. The active emphasis circuit is used to divide an input passband audio signal into a plurality of frequency zones, and adopt negative feedback of different depths for audio signals in different frequency zones to control the amplification multiples of audio signals in different frequency zones, thereby obtaining an emphasis on the high frequencies of the audio signals in the passband.

[0029] See also Figure 2 In this embodiment, the active emphasis circuit is a common-mode amplification active emphasis circuit, and the common-mode amplification active emphasis circuit includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first capacitor C1, a second capacitor C2 and a third capacitor C3.

[0030] The positive electrode of the active amplifier is connected to the input end of the transmitting circuit, the first resistor R1 is connected in parallel with the first capacitor C1, the third resistor R3 and the second capacitor C2 are connected in series and then connected in parallel with the second resistor R2, and the fourth resistor R4 and the third capacitor C3 are connected in series and then connected in parallel with the second resistor R2.

[0031] The first end of the first resistor R1, the first end of the first capacitor C1, the second end of the second resistor R2, the second end of the third resistor R3, and the second end of the fourth resistor R4 are respectively connected to the negative electrode of the active amplifier, the second end of the first resistor R1, the second end of the first capacitor C1, and the output end of the active amplifier are respectively connected to the output end of the transmitting circuit, and the first end of the second resistor R2, the first end of the second capacitor C2, and the first end of the third capacitor C3 are respectively grounded.

[0032] The in-phase amplification active emphasis circuit of the operational amplifier is adopted, the second resistor R2 is used to control the attenuation of the full frequency band relative to the mid-high frequency band and the high frequency band, the second capacitor C2 is used to separate the mid-high frequency band from the full frequency band, and the third capacitor C3 is used to separate the high frequency band from the full frequency band. The in-phase amplification active emphasis circuit is used to divide the audio signal in the passband into three frequency zones: R2, R3+C2, and R4+C3, and control the audio signals in different frequency zones with different amplification factors to obtain the emphasis of the mid-high frequency of the audio signal in the passband. Different negative feedback depths are used for different audio frequency bands to control their gains respectively. The first resistor R1 is a negative feedback resistor, the first capacitor C1 is a negative feedback capacitor, and the second resistor R2> the third resistor R3> the fourth resistor R4.

[0033] The first resistor R1 and the second resistor R2 are used to determine the bandwidth and amplification factor of the low frequency band in the passband. The first resistor R1, the third resistor R3 and the second capacitor C2 are used to determine the bandwidth and amplification factor of the medium and high frequency bands. The first resistor R1, the fourth resistor R4 and the third capacitor C3 are used to determine the bandwidth and amplification factor of the high frequency band. Using the in-phase amplification active emphasis circuit of the operational amplifier, the full-band amplification factor = (R1 / R2) + 1; under the condition of ignoring the capacitive reactance of the capacitor, the amplification factor of the medium and high frequency band = (R1 / R3) + 1; the amplification factor of the high frequency band = (R1 / R4) + 1. The in-phase amplification active emphasis circuit processes audio signals of different frequency bands with different amplification factors, that is, high-frequency pre-emphasis is performed.

[0034] Example 2

[0035] The utility model discloses a wireless audio transmission transmitting circuit, comprising an active amplifier, a resistor and a capacitor, wherein the active amplifier and a plurality of resistors and a plurality of capacitors form an active emphasis circuit, wherein the active amplifier is an operational amplifier. The active emphasis circuit is used to divide an input passband audio signal into a plurality of frequency zones, and adopt negative feedback of different depths for audio signals in different frequency zones to control the amplification multiples of audio signals in different frequency zones, thereby obtaining an emphasis on the high frequencies of the audio signals in the passband.

[0036] See also Figure 3In this embodiment, the active emphasis circuit is an inverting amplifying active emphasis circuit, and the inverting amplifying active emphasis circuit includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first capacitor C1 and a second capacitor C2.

[0037] The positive electrode of the active amplifier is grounded, the first end of the first resistor R1 is connected to the input end of the transmitting circuit, and the second end of the first resistor R1 and the first end of the second resistor R2 are respectively connected to the negative electrode of the active amplifier.

[0038] The first end of the third resistor R3, the first end of the fourth resistor R4, and the first end of the fifth resistor R5 are respectively connected to the second end of the second resistor R2, the fourth resistor R4 and the first capacitor C1 are connected in series, the fifth resistor R5 and the second capacitor C2 are connected in series, the second end of the third resistor R3 and the output end of the active amplifier are respectively connected to the output end of the transmitting circuit, and the second end of the first capacitor C1 and the second end of the second capacitor C2 are respectively grounded.

[0039] The inverting amplifier active emphasis circuit adopts an operational amplifier, the second resistor R2 and the third resistor R3 are used to control the attenuation of the full frequency band relative to the mid-high frequency band and the high frequency band, the first capacitor C1 is used to separate the mid-high frequency band from the full frequency band, and the second capacitor C2 is used to separate the high frequency band from the full frequency band. The inverting amplifier active emphasis circuit is used to divide the audio signal in the passband into three frequency zones of R1+R2+R3, R4+C1, and R5+C2 to control the amplification factor of the audio signal in different frequency zones and obtain the emphasis of the high frequency signal in the passband.

[0040] The first resistor R1, the second resistor R2 and the third resistor R3 are used to determine the bandwidth and amplification factor of the low frequency band in the passband. The fourth resistor R4 and the first capacitor C1 are used to determine the bandwidth and amplification factor of the medium and high frequency bands. The fifth resistor R5 and the second capacitor C2 are used to determine the bandwidth and amplification factor of the high frequency band.

[0041] In summary, the utility model forms an active emphasis circuit by setting an active amplifier, and the active amplifier and multiple resistors and multiple capacitors form an active emphasis circuit. The active emphasis circuit divides the input passband audio signal into multiple frequency zones to control the amplification factors of audio signals in different frequency zones, thereby obtaining emphasis on the high frequencies of the audio signal in the passband, and realizing "emphasis" between audio signal partitions, thus solving the frequency division within the passband and the independent amplification of different frequency zones, and realizing lossless audio emphasis.

[0042] The above description is a detailed description of the preferred feasible embodiments of the utility model, but the embodiments are not intended to limit the scope of the patent application of the utility model. All equivalent changes or modified changes completed under the technical spirit disclosed by the utility model should fall within the patent scope covered by the utility model.

Claims

1. A wireless audio transmission transmitting circuit, characterized in that: The active amplifier, the resistor and the capacitor form an active emphasis circuit, which is used to divide the input passband audio signal into multiple frequency zones, and use negative feedback of different depths for the audio signals in different frequency zones to control the amplification factors of the audio signals in different frequency zones, so as to obtain the emphasis on the high frequency of the audio signal in the passband; The active emphasis circuit is a common-phase amplification active emphasis circuit, which at least includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first capacitor C1, a second capacitor C2 and a third capacitor C3; The first end of the active amplifier is connected to the input end of the transmitting circuit, the first resistor R1 is connected in parallel with the first capacitor C1, the third resistor R3 and the second capacitor C2 are connected in series and then connected in parallel with the second resistor R2, and the fourth resistor R4 and the third capacitor C3 are connected in series and then connected in parallel with the second resistor R2; The first end of the first resistor R1, the first end of the first capacitor C1, the second end of the second resistor R2, the second end of the third resistor R3, and the second end of the fourth resistor R4 are respectively connected to the second end of the active amplifier, the second end of the first resistor R1, the second end of the first capacitor C1, and the third end of the active amplifier are respectively connected to the output end of the transmitting circuit, and the first end of the second resistor R2, the first end of the second capacitor C2, and the first end of the third capacitor C3 are respectively grounded; Or the active emphasis circuit is an inverting amplifying active emphasis circuit, which at least includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first capacitor C1 and a second capacitor C2; The first end of the active amplifier is grounded, the first end of the first resistor R1 is connected to the input end of the transmitting circuit, and the second end of the first resistor R1 and the first end of the second resistor R2 are respectively connected to the second end of the active amplifier; The first end of the third resistor R3, the first end of the fourth resistor R4, and the first end of the fifth resistor R5 are respectively connected to the second end of the second resistor R2, the fourth resistor R4 and the first capacitor C1 are connected in series, the fifth resistor R5 and the second capacitor C2 are connected in series, the second end of the third resistor R3 and the third end of the active amplifier are respectively connected to the output end of the transmitting circuit, and the second end of the first capacitor C1 and the second end of the second capacitor C2 are respectively grounded.

2. The wireless audio transmission transmitting circuit according to claim 1, characterized in that: The active amplifier is any one of an operational amplifier, a line amplifier, and a triode.

3. The wireless audio transmission transmitting circuit according to claim 2, characterized in that: An operational amplifier in-phase amplification active emphasis circuit is used, the second resistor R2 is used to control the attenuation of the full frequency band relative to the mid-high frequency band and the high frequency band, the second capacitor C2 is used to separate the mid-high frequency band from the full frequency band, and the third capacitor C3 is used to separate the high frequency band from the full frequency band.

4. The wireless audio transmission transmitting circuit according to claim 3, characterized in that: The in-phase amplification active emphasis circuit is used to divide the audio signal in the passband into multiple frequency zones, including at least three frequency zones of R2, R3+C2, and R4+C3, and control the audio signals in different frequency zones with different amplification factors to obtain the emphasis on the high frequencies of the audio signal in the passband.

5. The wireless audio transmission transmitting circuit according to claim 4, characterized in that: The in-phase amplifier active emphasis circuit is used to control the gain of different audio frequency bands by adopting different negative feedback depths. The first resistor R1 is a negative feedback resistor, the first capacitor C1 is a negative feedback capacitor, and the second resistor R2> the third resistor R3> the fourth resistor R4.

6. The wireless audio transmission transmitting circuit according to claim 5, characterized in that: The first resistor R1 and the second resistor R2 are used to determine the bandwidth and amplification factor of the low frequency band in the passband; the first resistor R1, the third resistor R3 and the second capacitor C2 are used to determine the bandwidth and amplification factor of the medium and high frequency bands; the first resistor R1, the fourth resistor R4 and the third capacitor C3 are used to determine the bandwidth and amplification factor of the high frequency band.

7. The wireless audio transmission transmitting circuit according to claim 6, characterized in that: Using the operational amplifier's in-phase amplification active emphasis circuit, the full-band amplification factor = (R1 / R2) + 1; under the condition of ignoring the capacitive reactance of the capacitor, the amplification factor of the medium and high frequency bands = (R1 / R3) + 1; the amplification factor of the high frequency band = (R1 / R4) + 1.

8. The wireless audio transmission transmitting circuit according to claim 2, characterized in that: An inverting amplification active emphasis circuit of an operational amplifier is adopted, the second resistor R2 and the third resistor R3 are used to control the attenuation of the full frequency band relative to the mid-high frequency band and the high frequency band, the first capacitor C1 is used to separate the mid-high frequency band from the full frequency band, and the second capacitor C2 is used to separate the high frequency band from the full frequency band.

9. The wireless audio transmission transmitting circuit according to claim 8, characterized in that: The inverting amplifier active emphasis circuit is used to divide the audio signal in the passband into multiple frequency zones, including at least three frequency zones of R1+R2+R3, R4+C1, and R5+C2, control the amplification factors of the audio signals in different frequency zones, and obtain the emphasis of the high-frequency signal in the passband.

10. The wireless audio transmission transmitting circuit according to claim 9, characterized in that: The first resistor R1, the second resistor R2 and the third resistor R3 are used to determine the bandwidth and amplification factor of the low frequency band in the passband; the fourth resistor R4 and the first capacitor C1 are used to determine the bandwidth and amplification factor of the medium and high frequency bands; the fifth resistor R5 and the second capacitor C2 are used to determine the bandwidth and amplification factor of the high frequency band.

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