手机音频走线规则

1，敏感走线（Mic，receiver，speaker等差分线）远离干扰源（如天线，battery走线，高速数字走线，开关电源）。
2，敏感走线尽量用GND包起来；条件允许，可以将个别干扰源也屏蔽起来。
3，Mic，Receiver，Speaker等差分信号线，需要严格差分走线（与线路匹配的相同的宽度，长度，厚度和阻抗），尽量避免差分对之间的分开——这样可以降低抑制共模噪声的能力。建议0.2mm。
4，尽量将敏感电路放在屏蔽罩内。
5，在敏感线路上预留滤波电路（磁珠、电容）。
6，Receiver走线上不宜并太大电容，过大的负载电容会导致放大器自激。
7，音频电路的接地要特别注意：
■ 基带音频IC需要充分接地（多打地孔到参考地）。
■ 不要和表层地连接。
■ 最好直接打孔到主参考地。
8，第一级放大器要靠近声源，尤其是Mic，滤波电路要尽可能的靠近Mic；
10.Mic信号是最敏感的，最好布在中间层，尽量少跨层走；
11.耳机HPH_R和HPH_L彼此分开走线，彼此平行走线会增强共模噪声；
12.在receiver、耳机线路上靠近音频功放输出端增加“磁珠”，抑制天线辐射对音频电路的干扰。
13.ESD器件就近布局，EDA设计时，走线应先进入ESD器件，再进入需要防护的器件；
14. Mic的ESD器件（TVS管）不能放在天线的净空区域

 

1.Run the differential (signal+, signal-) pair TOGETHER all the way from the MSM codec to the audio amplifier driver. 2. Run the differential pair such that the distance (separation) between them is constant at every point along the way (keep them TOGETHER and as close as possible). 3. Run the differential pair identical (match trace width/length/thickness and impedance). 4. Run the differential pair with GROUND GUARD FIELDS from the rest of the board (ground needs to be of lowest potential and, if possible, run on ground planes). 5. Run the differential on the quiet side of the PCB. Dedicate one side of PCB to have all analog signals. 6.Run the differential pair with the minimum distance from MSM codec to the PMIC speaker amplifier inputs. 7.Keep the input filter stage close to the PMIC speaker amplifier inputs. 8.Avoid running the differential signal traces from one layer to another, because transversing through vias could bottleneck your signal and cause a voltage drop. If you do run the signals from one layer to the next layer, make sure the vias can handle the current. Run the pair on the same board plane as much as possible. 9.Avoid separating the differential pair, because it could loose its immunity against common mode noise. 10. Run the pair AWAY from any digital signals (clocks, digital grounds, other high speed switches). 11. IPC-D-275 states that for an internal conductor a minimum of 4 mil (0.004 inches) of conductor spacing is needed for voltages between conductors of 0-15 V DC or AC peaks. 12. Minimize MSM codec to transducer signal trace length (keep the system to close proximity). 13. Avoid sharp turns of signal traces. 14. Avoid running signals close to RF/antenna, especially the input signals. 15. Place Cin close to PMIC speaker amplifier. 16. Single-ended input configuration trace from MSM codec to PMIC needs ground fills