Touch Signal Calibration Circuit for High-Gain Quantization Error

The calibration process is divided into two distinct stages: a first calibration stage that performs coarse calibration to correct large-scale offset errors, and a second calibration stage that performs fine calibration to correct remaining quantization errors. This segmentation allows each stage to be optimized for its specific purpose, enabling accurate calibration even with high gain amplification.

The first calibration is performed as a preliminary action before the second calibration. By预先 correcting the major offset errors in the first calibration stage, the system prepares the signal path for more precise second calibration, ensuring that quantization errors are minimized before final measurement.

The calibration range is segmented into coarse calibration (first calibration) and fine calibration (second calibration). The first calibration handles the majority of the calibration range with coarser resolution, while the second calibration focuses on the remaining small range with fine 1-LSB precision. This segmentation achieves high precision without requiring the entire system to be designed for 1-LSB precision from the start, thus reducing die area.

Instead of performing full-range high-precision calibration throughout the entire system, the patent applies partial high-precision calibration only in the second calibration stage for the remaining error range. This partial application of high precision where needed minimizes the overall die area while achieving the required calibration accuracy.