A hardware circuit for connecting a high-power speaker to a headphone jack

Abstract

The utility model discloses a hardware circuit for connecting a high-power speaker with a headphone jack, including an audio codec, an audio power amplifier and a speaker, wherein the LINEOUT port of the audio codec is respectively connected to a filter capacitor C1 and a filter capacitor C2 through a Π-type circuit, wherein the filter capacitor C2 is connected in series with a resistor R4, and the resistor R4 is connected to the audio power amplifier, and the audio power amplifier is connected to the speaker through an analog signal; the Π-type circuit is composed of a resistor R1, a resistor R2 and a resistor R3. The utility model adds series magnetic beads FB1 and FB2 to the back end of the audio power amplifier, and adds parallel capacitors C3 and C4 to form a low-pass filter network, which can effectively filter out high-frequency stray signals while ensuring that the main audio signal is not attenuated; thereby effectively improving the interference problem of the entire circuit to other radio frequency systems.

Description

Technical Field

[0001] The utility model relates to the technical field related to earphone jack circuits, in particular to a hardware circuit for connecting a high-power speaker with an earphone jack. Background Art

[0002] In recent years, the sales volume of portable devices represented by mobile phones has reached an unprecedented level. As a result, the price of mobile phone chips has been greatly reduced. The low price of chips brought by the supply chain has caused a chain reaction. Many other non-mobile or portable products have also begun to use mobile phone chips to realize product design, thereby maximizing the advantages of the low-cost supply chain of mobile phones and other portable devices, and maximizing the high computing power of mobile phone chips, to achieve the demand for lower prices and better quality of their own product categories.

[0003] However, mobile phone chips are designed for portable devices such as mobile phones and tablets, and the chip architecture is not universal for all electronic products. Therefore, we need to make corresponding circuit innovations.

[0004] Taking the audio as an example, the power of the speaker of a mobile phone is much lower than that of non-portable devices such as TVs and projectors. Generally, a speaker has a power of only 1W or less. From the perspective of circuit implementation, the mobile phone chip will directly output analog audio signals or digital signals, which will drive the speaker to the corresponding power through a power amplifier with a specific gain. The circuit implementation is very simple. All related risks have been taken into account inside the mobile phone chip, so the external circuit will not be complicated. There will be a reference design, and this reference design can be directly applied.

[0005] If the mobile phone chip is used in non-portable devices such as smart TVs or smart projectors, the traditional circuit link is used to drive a speaker with only 1W power, and the volume is obviously far from enough. Users will not be able to hear the sound, or the sound quality will not meet the ideal situation.

[0006] Existing technologies such as Figure 3 and 4 As shown, Figure 3 This is the most traditional approach, which outputs analog signals to an audio amplifier, which then amplifies the signals and drives the speakers to produce sound. Figure 4 This is a common method in recent years. The audio encoder outputs the digital audio signal IIS to the audio PA, and the audio PA is then used to drive the speaker to produce sound. Figure 3 or Figure 4, are all driving a relatively small speaker to produce sound, usually at the level of 0.5W to 1W. If the speaker is larger, it cannot be driven. The main reason is as mentioned above, the amplification gain of the audio amplifier is too high, which will cause various problems. If it must be amplified in this link, it must be amplified in two stages, and the complexity of the circuit design will increase, which is not a very ideal design idea. Utility Model Content

[0007] The utility model aims to provide a hardware circuit for connecting a high-power speaker with an earphone jack, so as to solve the problems in the prior art.

[0008] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: a hardware circuit for connecting a high-power speaker with a headphone jack, comprising an audio codec, an audio power amplifier and a speaker, wherein the LINEOUT port of the audio codec is respectively connected to a filter capacitor C1 and a filter capacitor C2 through a Π-type circuit, wherein the filter capacitor C2 is connected in series with a resistor R4, which is connected to the audio power amplifier, and the audio power amplifier is connected to the speaker through an analog signal; the Π-type circuit is composed of a resistor R1, a resistor R2 and a resistor R3.

[0009] Preferably, the resistance values ​​of the resistor R2 and the resistor R3 are the same.

[0010] Preferably, a two-end output circuit network is used between the audio power amplifier and the speaker, and the two-end output circuit network includes a magnetic bead FB1, a magnetic bead FB2, a capacitor C3 and a capacitor C4, the magnetic bead FB1 is connected to the capacitor C3, and the magnetic bead FB2 is connected to the capacitor C4.

[0011] Compared with the prior art, the beneficial effects of the utility model are:

[0012] The network includes a Π-type resistor network, including three resistors, one of which, R1, is connected in series, and the other two resistors, R2 and R3, are connected in parallel to the ground and are placed at both ends of the resistor R1 respectively; the resistor R1 is used to adjust the attenuation value, and the resistors R2 and R3 are used to adjust the characteristic impedance to a specific value.

[0013] Through a capacitor C1 connected in parallel to the ground, the first level of filtering is achieved, which can effectively remove some RF noise, such as GSM TDD noise. Through a series filter network capacitor C2 and resistor R4, the cutoff frequency of the entire input signal can be effectively adjusted to effectively isolate low-frequency signals.

[0014] At the back end of the audio amplifier, add series magnetic beads FB1 and FB2, and add parallel capacitors C3 and C4 to form a low-pass filter network, which can effectively filter out high-frequency stray signals while ensuring that the main audio signal is not attenuated; thereby effectively improving the interference problem of the entire circuit to other RF systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0016] Figure 1 It is the principle diagram of the utility model;

[0017] Figure 2 It is a circuit diagram of the utility model;

[0018] Figure 3 It is a structural schematic diagram of one of the prior art of the utility model;

[0019] Figure 4 It is another structural schematic diagram of the prior art of the utility model. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model. Therefore, the following detailed description of the embodiments of the utility model provided in the drawings is not intended to limit the scope of the utility model for which protection is claimed, but merely represents selected embodiments of the utility model.

[0021] See also Figure 1-2In the embodiment of the utility model, a hardware circuit for connecting a high-power speaker with a headphone jack includes an audio codec, an audio power amplifier and a speaker. The LINEOUT port of the audio codec is connected to the filter capacitor C1 and the filter capacitor C2 respectively through a Π-type circuit. The filter capacitor C2 is connected in series with a resistor R4, and the resistor R4 is connected to the audio power amplifier, and the audio power amplifier is connected to the speaker through an analog signal; the Π-type circuit is composed of a resistor R1, a resistor R2 and a resistor R3; the resistance values ​​of the resistors R2 and R3 are the same. The network includes a Π-type resistor network, including three resistors, one of which is a resistor R1 in series, and the other two resistors R2 and R3 are connected in parallel to the ground, and are placed at both ends of the resistor R1. The function of the resistor R1 is to adjust the attenuation value, and the resistors R2 and R3 are to adjust the characteristic impedance to a specific value.

[0022] The following are some examples of implementation methods:

[0023] Assume that the characteristic impedance we want to control is 50 ohms. The power we need to attenuate is 2dB. Then according to the simulation results, we can get: resistance R1 = 11.6 ohms; resistance R2 = resistance R3 = 436 ohms.

[0024] A double-ended output circuit network is used between the audio power amplifier and the speaker. The double-ended output circuit network includes a magnetic bead FB1, a magnetic bead FB2, a capacitor C3 and a capacitor C4. The magnetic bead FB1 is connected to the capacitor C3, and the magnetic bead FB2 is connected to the capacitor C4.

[0025] First, a capacitor C1 connected in parallel to the ground is used to achieve the purpose of first-level filtering, which can effectively remove some RF noise, such as GSM TDD noise.

[0026] Second, through a series filter network capacitor C2 and resistor R4, the cutoff frequency of the entire input signal can be effectively adjusted to effectively isolate the low-frequency signal.

[0027] At the back end of the audio amplifier, add series magnetic beads FB1 and FB2, add parallel capacitors C3 and C4 to form a low-pass filter network, which can effectively filter out high-frequency stray signals while ensuring that the main audio signal is not attenuated, thereby effectively improving the interference problem of the entire circuit to other radio frequency systems.

[0028] After the LINEOUT headphone interface is output, it first passes through a Π-type circuit, which is composed of resistors R1, R2, and R3. Its function is to attenuate the power of the link in the entire frequency band without changing the characteristic impedance of the link. In the design of this Π-type network, several aspects need to be paid attention to:

[0029] First, we need to pay attention to characteristic impedance control. The general RF signal impedance control uses 50 ohm characteristic impedance as the link impedance control benchmark. Then the input and output ends of our π-type network are matched with 50 ohm characteristic impedance.

[0030] Secondly, the attenuation network composed of resistors has no frequency selection characteristics, that is, in a wide frequency range, the attenuation value of the attenuation network composed of resistors is consistent. In this way, the attenuation value we calculated will not change with the frequency. This is an important reason why we choose to use a resistor network for attenuation. Other attenuation networks, such as an attenuation circuit that connects a large capacitor in parallel to the ground, are more difficult to control, and the attenuation of high frequencies is greater than that of low frequencies. So it is very difficult to control.

[0031] Finally, when applying this network, it should be noted that the values ​​of resistors R2 and R3 are the same. Their main function is to pull back the characteristic impedance to 50 ohms. The value of resistor R1 can be different from that of resistors R2 and R3. It is the main force of attenuation. By adjusting the resistance values ​​of these three resistors, we can adjust the attenuation value steplessly. It is very convenient to control the attenuation.

[0032] Behind the π-type network, C1 is a filter capacitor. Generally, we will select a value of about 10nF to filter out RF signals, especially GSM TDD noise. Special attention should be paid to the selection of this capacitor, because the 217Hz GSM TDDNoise also falls within the range that can be heard by the human ear, so this C1 capacitor will actually attenuate useful signals. Therefore, the selection of C1 should be used in conjunction with the π-type attenuation circuit of resistors R1, R2, and R3 mentioned above. And the capacitance value should not be too large.

[0033] Behind the C1 filter capacitor, C2 and resistor R4 are used to adjust the cutoff frequency of the audio amplifier. It can also be regarded as a filter circuit. Its function is to select the frequency of the signal input to the audio amplifier. It can also remove some low-frequency noise signals, such as the TDD Noise mentioned above. However, it should be noted that if the low frequency is suppressed too high, the low-frequency performance of the music will deteriorate. At the same time, the general resistor R4 plays a role in adjusting the gain of the following amplifier. In conjunction with the feedback resistor inside the amplifier, it is used to adjust the final amplification gain of the amplifier.

[0034] The circuit network behind the audio amplifier is a double-ended output. It is used to connect the speaker. Among them, FB1 and FB2 are magnetic beads with frequency selection characteristics, which can filter out some high-frequency signals. The functions of C3 and C4 to the ground are the same as FB1 and FB2, and they are also low-pass filtering links. These four devices work together to filter out high-frequency components, while preventing the main audio signal from being attenuated. The purpose of filtering out high-frequency signals is to reduce radio frequency clutter and reduce the impact on other communication equipment.

[0035] Finally, it should be noted that the above description is only a preferred embodiment of the utility model and is not intended to limit the utility model. Although the utility model is described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions recorded in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A hardware circuit for connecting a headphone jack to a high-power speaker, comprising an audio codec, an audio power amplifier and a speaker, characterized in that: The LINEOUT port of the audio codec is connected to the filter capacitor C1 and the filter capacitor C2 respectively through a Π-type circuit, the filter capacitor C2 is connected in series with a resistor R4, the resistor R4 is connected to an audio power amplifier, and the audio power amplifier is connected to a speaker through an analog signal; The II-type circuit is composed of a resistor R1, a resistor R2 and a resistor R3.

2. A hardware circuit for connecting a headphone jack to a high-power speaker according to claim 1, characterized in that: The resistance values ​​of the resistor R2 and the resistor R3 are the same.

3. The hardware circuit for connecting a headphone jack to a high-power speaker according to claim 1, characterized in that: A double-ended output circuit network is used between the audio power amplifier and the speaker. The double-ended output circuit network includes a magnetic bead FB1, a magnetic bead FB2, a capacitor C3 and a capacitor C4. The magnetic bead FB1 is connected to the capacitor C3, and the magnetic bead FB2 is connected to the capacitor C4.

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