CDAC冗余位权重问题

firefly星

有人知道这种冗余，直接添加一位电容的方式，它在计算Dout的时候，对应的冗余位的权重B3c计算的时候为什么要减去0.5呢，没有太理解？这里是4bit的示例，加冗余权重是8 4 2 2 1，

ethanchung

Why Subtract 0.5?

The 0.5 subtraction is related to the way the 3-term compensation algorithm works. It's essentially a rounding factor. Here's a simplified explanation:

Error Calculation: The algorithm calculates the error between the ideal DAC output and the actual output due to capacitor imperfections.
Compensation Terms: This error is then divided into three parts, each corresponding to a different source of error.
Digital Correction: These error terms are converted into digital values and used to adjust the DAC's output during the conversion process.
The 0.5 subtraction comes in during the digital correction step. It helps to ensure that the digital correction value is rounded to the nearest integer, effectively minimizing the overall error.