原创 DAC Layout Guide

（注：DAC5682的layout guide迄今为止尚未找到，下面以AD797为例，希望能够举一反三）

Every design should have different requirements, PCB stackup, via size, PCB size, component sizes, etc. ESS finds and recommendates to use only one ground plane for both digital and analog grounds as it simplifies layout design and provides no performance degradation. The most important for DAC layout is ground plane. It should be as solid as possible with as few traces routed through the ground plane as possible. Any traces that are routed through the ground plane and block the 'line of sight'  from the DAC output to the opamp output stage significantly degrades the output THD. 

(note: THD:Total Harmonic Distortion 总谐波失真

           SNR: Signal Noise Ratio 信噪比)

Critical PCB layout items:

1. Make sure the ground plane as solid as possible. Try to keep all ground connections as short as possible. Every ground connections should have its own via, do not share vias if possible.  

   确保地平面连续。所有地走线越短越好。每个地走线都应有自己的过孔，过孔不能共用。

2. Keep opamp feedback paths as close as possible to the opamp.

 确保运放的反馈回路离运放本身越近越好。

3. Ensure every opamp and DAC has its own power supply decoupling capacitance right next to the power supply pins.

确保运放和DAC的电源引脚有足够的去耦电容，而且靠近电源引脚摆放。

4. Try to keep the digital circuitry away from the analog circuitry.

确保数字电路和模拟电路分开。

总结：对于DAC和ADC 的 PCB LAYOUT而言，重点就在于模拟和数字的分开问题，包括circuitry和power部分。