Touch Signal Calibration Circuit for High-Gain Quantization Error

The calibration process is divided into two distinct stages: coarse calibration using a first DAC to correct large offset errors, and fine calibration using a second DAC to correct remaining quantization errors. This segmentation allows each stage to address specific error components effectively, enabling accurate calibration even with high gain amplification.

The first DAC performs preliminary coarse calibration by providing a calibration voltage that corrects large offset errors in the touch signal before the signal undergoes high gain amplification. This preliminary correction prevents large errors from being amplified, making subsequent fine calibration more effective and reducing the overall calibration complexity.

The calibration system is segmented into two functional blocks: a first DAC for coarse calibration and a second DAC for fine calibration. This segmentation allows the use of lower-resolution DACs instead of a single high-resolution DAC, significantly reducing the total die area while achieving the same overall calibration precision.

The first DAC performs partial calibration by correcting the most significant bits of the offset error, while the second DAC handles the remaining less significant bits. This partial division of calibration tasks allows each DAC to use lower resolution, reducing total area while maintaining full calibration precision.