A Bluetooth audio circuit board, a Bluetooth headset and a design method

Abstract

The present invention is applicable to the field of circuit board design, and provides a Bluetooth audio circuit board, a Bluetooth headset and a design method. The Bluetooth audio circuit board adopts a serpentine trace as an inductor in an LC filter circuit for eliminating TDMA noise, and cooperates with a corresponding connected capacitor to filter out a 2.4GHZ signal from an audio output signal, thereby solving the TDMA noise problem, and has low implementation cost, and the inductance value is easy to control, and its tolerance can be controlled within + / -10%. In addition, the first serpentine trace pair and / or the second serpentine trace pair can adopt symmetrical wiring to make the inductance value more consistent.

Description

Technical Field

[0001] The invention belongs to the field of circuit board design, and in particular relates to a Bluetooth audio circuit board, a Bluetooth headset and a design method. Background Art

[0002] In the prior art, the Bluetooth RF signal of the Bluetooth audio circuit board may be coupled to the audio differential output terminal, directly introducing TDMA noise into the audio loop. For this reason, an LC filter circuit is usually set at the audio differential output terminal to filter out the 2.4GHZ signal from the audio output signal.

[0003] Specifically, Figure 1 As shown. The Bluetooth audio circuit board includes two audio differential output terminals, namely the left ear audio differential output terminal and the right ear audio differential output terminal. Correspondingly, the Bluetooth audio processing circuit on the Bluetooth audio circuit board includes two pairs of audio output terminals, namely the left ear audio output terminal and the right ear audio output terminal. Among them, the left ear differential output positive terminal L+ is connected to the left ear positive output terminal A of the Bluetooth audio processing circuit of the Bluetooth audio circuit board through the LC filter circuit composed of inductor L1 and capacitor C1, and the left ear differential output negative terminal L- of the Bluetooth audio circuit board is connected to the left ear negative output terminal B of the Bluetooth audio processing circuit through the LC filter circuit composed of inductor L2 and capacitor C2; the right ear differential output positive terminal R+ of the Bluetooth audio circuit board is connected to the right ear positive output terminal C of the Bluetooth audio processing circuit through the LC filter circuit composed of inductor L3 and capacitor C3, and the right ear differential output negative terminal R- of the Bluetooth audio circuit board is connected to the left ear negative output terminal D through the LC filter circuit composed of inductor L4 and capacitor C4.

[0004] Since the inductor component in the LC filter circuit is in the form of a plug-in on the Bluetooth audio circuit board, the cost is relatively high and the inductance value is difficult to control. Its tolerance is generally + / - 20%, which is a large tolerance. Summary of the invention

[0005] The purpose of the embodiment of the present invention is to provide a Bluetooth audio circuit board, aiming to solve the problem that the inductor of the LC filter circuit used to eliminate TDMA noise in the Bluetooth audio circuit board provided by the prior art adopts a plug-in form, which has high cost and large tolerance.

[0006] The embodiment of the present invention is implemented as follows: a Bluetooth audio circuit board includes a top layer and a bottom layer as signal layers, and the Bluetooth audio circuit board further includes: a first serpentine trace pair arranged on the top layer or the bottom layer;

[0007] The first serpentine trace pair includes two serpentine traces, and the two terminals at the first end of the first serpentine trace pair are respectively connected one-to-one with the two terminals of the first pair of audio output ends of the Bluetooth audio processing circuit on the Bluetooth audio circuit board, and the two terminals at the second end of the first serpentine trace pair serve as the first audio differential output end of the Bluetooth audio circuit board. Capacitors are also respectively arranged between the traces between the two terminals at the first end of the first serpentine trace pair and the two terminals of the first pair of audio output ends connected accordingly and the ground.

[0008] Another object of an embodiment of the present invention is to provide a Bluetooth headset, comprising a Bluetooth audio circuit board, wherein the Bluetooth audio circuit board is the Bluetooth audio circuit board as described above.

[0009] Another object of an embodiment of the present invention is to provide a Bluetooth audio circuit board design method, comprising a top layer and a bottom layer as a signal layer, the Bluetooth audio circuit board design method comprising: arranging a first serpentine routing pair on the top layer or the bottom layer;

[0010] The first serpentine trace pair includes two serpentine traces, and the two terminals at the first end of the first serpentine trace pair are respectively connected one-to-one with the two terminals of the first pair of audio output ends of the Bluetooth audio processing circuit on the Bluetooth audio circuit board, and the two terminals at the second end of the first serpentine trace pair serve as the first audio differential output ends of the Bluetooth audio circuit board. Capacitors are also respectively arranged between the traces between the two terminals at the first end of the first serpentine trace pair and the two terminals of the first pair of audio output ends connected accordingly and the ground.

[0011] The Bluetooth audio circuit board provided by the embodiment of the present invention uses a serpentine trace as an inductor in an LC filter circuit for eliminating TDMA noise, and cooperates with a corresponding connected capacitor to filter out a 2.4GHZ signal from an audio output signal, thereby solving the TDMA noise problem, and has low implementation cost, and the inductance value is easy to control, and its tolerance can be controlled within + / - 10%. In addition, the first serpentine trace pair and / or the second serpentine trace pair can be symmetrically wired to make the inductance value more consistent. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is the circuit schematic of the Bluetooth audio circuit board;

[0013] Figure 2 This is a partial circuit board wiring diagram of the Bluetooth audio circuit board provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0015] In view of the problems existing in the prior art, an embodiment of the present invention provides a Bluetooth audio circuit board, which uses a serpentine trace as an inductor in an LC filter circuit for eliminating TDMA noise.

[0016] The Bluetooth audio circuit board can be a double-layer board or a multi-layer board, for example, a 2-layer board, a 4-layer board, a 6-layer board or an 8-layer board. The Bluetooth audio circuit board includes at least a top layer and a bottom layer as signal layers, and for a 4-layer board, a ground layer and a via wiring layer arranged between the top layer and the bottom layer, and for a 6-layer board or an 8-layer board, a power layer, a ground layer and several auxiliary signal layers arranged between the top layer and the bottom layer.

[0017] In an embodiment of the present invention, a first serpentine trace pair is arranged on the top layer or the bottom layer of the Bluetooth audio circuit board, the first serpentine trace pair includes two serpentine traces, the two terminals at the first end of the first serpentine trace pair are respectively connected one-to-one with the two terminals of the first pair of audio output ends of the Bluetooth audio processing circuit on the Bluetooth audio circuit board, the two terminals at the second end of the first serpentine trace pair serve as the first audio differential output ends of the Bluetooth audio circuit board, and capacitors are respectively arranged between the traces between the two terminals at the first end of the first serpentine trace pair and the two terminals of the first pair of audio output ends connected accordingly and the ground.

[0018] Furthermore, a second serpentine trace pair may be provided on the top layer or the bottom layer of the Bluetooth audio circuit board, the second serpentine trace pair comprising two serpentine traces, the two terminals at the first end of the second serpentine trace pair being respectively connected one-to-one with the two terminals of the second pair of audio output terminals of the Bluetooth audio processing circuit on the Bluetooth audio circuit board, the two terminals at the second end of the second serpentine trace pair serving as the second audio differential output terminals of the Bluetooth audio circuit board, and capacitors being respectively provided between the traces between the two terminals at the first end of the second serpentine trace pair and the two terminals of the correspondingly connected second pair of audio output terminals and the ground.

[0019] Among them, the serpentine routing, as a special curve, is a commonly used routing method in PCB wiring design. It is a special equal-length routing, and its shape details are determined by the set values ​​of parameters such as coupling distance (Gap), line width, coupling amplitude (Ap), etc. Preferably, in an embodiment of the present invention, the parallel line segments at the top of the serpentine routing are on the same straight line, the parallel line segments at the bottom of the serpentine routing are on the same straight line, and the coupling distance (Gap) is 0.1mm-0.6mm, the line width is 0.1mm-0.6mm, the coupling amplitude (Ap) is 5mm-30mm, and the number of parallel line segments at the top or bottom of the serpentine routing is 4-20.

[0020] Among them, the first pair of audio output terminals can be right ear audio output terminals, including right ear positive output terminal C and right ear negative output terminal D, and the corresponding first audio differential output terminal is the right ear audio differential output terminal, including right ear differential output positive terminal R+ and right ear differential output negative terminal R-; the second pair of audio output terminals can be left ear audio output terminals, including left ear positive output terminal A and left ear negative output terminal B, and the corresponding second audio differential output terminal is the left ear audio differential output terminal, including left ear differential output positive terminal L+ and left ear differential output negative terminal L-. Of course, the first pair of audio output terminals can also be left ear audio output terminals, and the corresponding first audio differential output terminal is the left ear audio differential output terminal; the second pair of audio output terminals are right ear audio output terminals, and the corresponding second audio differential output terminal is the right ear audio differential output terminal.

[0021] For example, if Figure 2 As shown, a first serpentine pair of traces is arranged on the top layer or bottom layer of the Bluetooth audio circuit board, and the first serpentine pair of traces includes serpentine trace 1 and serpentine trace 2. One end of serpentine trace 1 is connected to the right ear positive output terminal C of the Bluetooth audio processing circuit, one end of serpentine trace 2 is connected to the right ear negative output terminal D of the Bluetooth audio processing circuit, the other end of serpentine trace 1 is used as the right ear differential output positive terminal R+ of the Bluetooth audio circuit board, and the other end of serpentine trace 2 is used as the right ear differential output negative terminal R- of the Bluetooth audio circuit board. A capacitor C3 is arranged between the trace between serpentine trace 1 and the right ear positive output terminal C and the ground, and a capacitor C4 is arranged between the trace between serpentine trace 2 and the right ear negative output terminal D and the ground. Similarly, a second serpentine pair of traces can also be arranged on the top layer or bottom layer of the Bluetooth audio circuit board to correspondingly connect the left ear positive output terminal A and the left ear negative output terminal B, as well as the left ear differential output positive terminal L+ and the left ear differential output negative terminal L-, which will not be repeated.

[0022] In this way, the serpentine trace can be used as the inductor of the Bluetooth audio circuit board, and with the corresponding connected capacitor, a low-pass filter is formed to filter out the 2.4GHZ signal from the audio output signal, thereby solving the TDMA noise problem. The implementation cost is low, and the inductance value is easy to control, and its tolerance can be controlled within + / - 10%.

[0023] In the embodiment of the present invention, the first serpentine routing pair and / or the second serpentine routing pair are / is symmetrically wired, so that the same routing length and width can make the inductance value more consistent.

[0024] An embodiment of the present invention further provides a Bluetooth headset, including the Bluetooth audio circuit board as described above, which will not be described in detail.

[0025] An embodiment of the present invention further provides a method for designing a Bluetooth audio circuit board, comprising a top layer and a bottom layer as a signal layer, the method for designing a Bluetooth audio circuit board comprising: arranging a first serpentine routing pair on the top layer or the bottom layer;

[0026] The first serpentine trace pair includes two serpentine traces, and the two terminals at the first end of the first serpentine trace pair are respectively connected one-to-one with the two terminals of the first pair of audio output ends of the Bluetooth audio processing circuit on the Bluetooth audio circuit board, and the two terminals at the second end of the first serpentine trace pair serve as the first audio differential output ends of the Bluetooth audio circuit board. Capacitors are also respectively arranged between the traces between the two terminals at the first end of the first serpentine trace pair and the two terminals of the first pair of audio output ends connected accordingly and the ground.

[0027] In summary, the Bluetooth audio circuit board provided by the embodiment of the present invention uses a serpentine trace as an inductor in an LC filter circuit for eliminating TDMA noise, and cooperates with a corresponding connected capacitor to filter out a 2.4GHZ signal from an audio output signal, thereby solving the TDMA noise problem, and has low implementation cost, and the inductance value is easy to control, and its tolerance can be controlled within + / -10%. In addition, the first serpentine trace pair and / or the second serpentine trace pair can be symmetrically wired to make the inductance value more consistent.

[0028] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A Bluetooth audio circuit board, comprising a top layer and a bottom layer as a signal layer, characterized in that: The Bluetooth audio circuit board further includes: a first serpentine wiring pair arranged on the top layer or the bottom layer; The first serpentine trace pair includes two serpentine traces, two terminals at the first end of the first serpentine trace pair are respectively connected to two terminals of the first pair of audio output terminals of the Bluetooth audio processing circuit on the Bluetooth audio circuit board in a one-to-one correspondence, two terminals at the second end of the first serpentine trace pair serve as the first audio differential output terminals of the Bluetooth audio circuit board, and capacitors are respectively provided between the traces between the two terminals at the first end of the first serpentine trace pair and the two terminals of the first pair of audio output terminals connected thereto and the ground; The first serpentine routing pair adopts symmetrical routing; The parallel line segments at the top of the serpentine route are on the same straight line, the parallel line segments at the bottom of the serpentine route are on the same straight line, and the coupling distance of the serpentine route is 0.1mm-0.6mm, the line width of the serpentine route is 0.1mm-0.6mm, the coupling amplitude of the serpentine route is 5mm-30mm, and the number of parallel line segments at the top or bottom of the serpentine route is 4-20.

2. The Bluetooth audio circuit board as claimed in claim 1, characterized in that: The Bluetooth audio circuit board further includes: a second serpentine wiring pair arranged on the top layer or the bottom layer; The second serpentine trace pair includes two serpentine traces, and the two terminals at the first end of the second serpentine trace pair are respectively connected one-to-one with the two terminals of the second pair of audio output ends of the Bluetooth audio processing circuit, and the two terminals at the second end of the second serpentine trace pair serve as the second audio differential output ends of the Bluetooth audio circuit board. Capacitors are also respectively arranged between the traces between the two terminals at the first end of the second serpentine trace pair and the two terminals of the correspondingly connected second pair of audio output ends and the ground.

3. The Bluetooth audio circuit board as claimed in claim 2, characterized in that: The first pair of audio output terminals are right-ear audio output terminals, the right-ear audio output terminals include a right-ear positive output terminal and a right-ear negative output terminal, the first audio differential output terminal is a right-ear audio differential output terminal, the right-ear audio differential output terminal includes a right-ear differential output positive terminal and a right-ear differential output negative terminal; The second pair of audio output terminals are left ear audio output terminals, the left ear audio output terminals include a left ear positive output terminal and a left ear negative output terminal, and the second audio differential output terminal is a left ear audio differential output terminal, the left ear audio differential output terminal includes a left ear differential output positive terminal and a left ear differential output negative terminal.

4. The Bluetooth audio circuit board according to any one of claims 1 to 3, characterized in that: The Bluetooth audio circuit board is a 2-layer board, and the 2-layer board includes a top layer and a bottom layer as signal layers.

5. The Bluetooth audio circuit board according to any one of claims 1 to 3, characterized in that: The Bluetooth audio circuit board is a four-layer board, which includes a top layer and a bottom layer as signal layers, and also includes a ground layer and a via wiring layer arranged between the top layer and the bottom layer.

6. The Bluetooth audio circuit board according to any one of claims 1 to 3, characterized in that: The Bluetooth audio circuit board is a 6-layer board or an 8-layer board, and the 6-layer board or the 8-layer board includes the top layer and the bottom layer as signal layers, and also includes a power layer, a ground layer and several auxiliary signal layers arranged between the top layer and the bottom layer.

7. A Bluetooth headset, comprising a Bluetooth audio circuit board, characterized in that: The Bluetooth audio circuit board is the Bluetooth audio circuit board as described in any one of claims 1 to 6.

8. A method for designing a Bluetooth audio circuit board, comprising a top layer and a bottom layer as a signal layer, characterized in that: The Bluetooth audio circuit board design method comprises: arranging a first serpentine routing pair on the top layer or the bottom layer; The first serpentine trace pair includes two serpentine traces, two terminals at the first end of the first serpentine trace pair are respectively connected to two terminals of a first pair of audio output ends of a Bluetooth audio processing circuit on a Bluetooth audio circuit board in a one-to-one correspondence, two terminals at the second end of the first serpentine trace pair serve as a first audio differential output end of the Bluetooth audio circuit board, and capacitors are respectively provided between the traces between the two terminals at the first end of the first serpentine trace pair and the two terminals of the first pair of audio output ends connected thereto and the ground; The first serpentine routing pair adopts symmetrical routing; The parallel line segments at the top of the serpentine route are on the same straight line, the parallel line segments at the bottom of the serpentine route are on the same straight line, and the coupling distance of the serpentine route is 0.1mm-0.6mm, the line width of the serpentine route is 0.1mm-0.6mm, the coupling amplitude of the serpentine route is 5mm-30mm, and the number of parallel line segments at the top or bottom of the serpentine route is 4-20.

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