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我正在开发一个用于模拟传感应用的PCB。它在PSoC3上使用12位Delta Sigma ADC。像往常一样，应用程序非常受空间限制（11mm×21mm），所以我不得不在PCB版图上做出一些妥协，而我不会在更大的PCB上这样做。
该板是由规定6V，并包含两个5V线性稳压器。用于数字电源的MCP1702和模拟电源的MIC5205。该板感测五个A1324霍尔效应传感器。每个霍尔效应输出信号由100NF+1K RC滤波器滤波。一个传感器在PCB本身（右下角）。另4个插头插入右手6针连接器。芯片是一个SPI从机，但是ADC采样总是在SPI事务之间进行，所以SPI不应该干扰模拟信号。可悲的是，我仍然看到一些噪音（大约1.5 LSB在12位）上的模拟信号，我不知道是否有什么我可以做不同的（在布局或其他方面），以改善它。
我用MC2308完成的其他PCB设计，和相同的双5V电源，相同的传感器，和相同的RC滤波器在12位没有达到明显的噪声。我真的想把它推向12 eNoB。原因不是准确度，而是速度测量。目前，这种噪声水平使得机器人无法进行精确的位置和速度控制。
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     以下为原文
   I am developing a PCB for an analogue sensing application. It uses the 12-bit Delta Sigma ADC on a PSoC3. As usual, the application is very space constrained (11mm x 21mm), so I have had to make some compromises in the PCB layout which I would not have done on a larger PCB.
    The board is supplied by regulated 6v, and contains two 5v linear regulators. An MCP1702 for the digital supply, and an MIC5205 for the analogue supply. The board is sensing five A1324 Hall effect sensors. Each Hall effect output signal is filtered by a 100nF + 1k RC filter. One sensor is on the PCB itself (bottom right). The other 4 plug into the right hand 6-pin connector.

The chip is acting as an SPI slave, but ADC samples are always taken between SPI transactions, so the SPI should not interfere with the analogue signals.

Sadly, I am still seeing some noise (about 1.5 LSB at 12-bits) on the analogue signals, and I wonder if there is anything I could have done differently (in the layout or otherwise) to improve it.
    Other PCB designs I have done using the MCP2308, and the same dual 5v supplies, same sensors, and same RC filters have achieved no noticeable noise at 12 bits.

I would really like to push it towards 12 ENOB. The reason is not accuracy, but velocity measurement. Currently this level of noise is making it impossible to do accurate position and velocity control on a robot.

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