Implementation of a Real-Time Calibration Method for Nonlinear ADC Links Based on Compensation Sequence Lookup Tables

This paper introduces a real-time calibration method for analog-to-digital conversion (ADC) link nonlinearity using a compensation sequence lookup table (LUT), implemented on an FPGA. The approach includes offline extraction of nonlinear errors and FPGA-based real-time calibration. Offline extraction uses a sinusoidal code density histogram to derive the compensation sequence, while the FPGA calibration unit—comprising an input converter, storage unit, compensation calculator, and buffer output—applies real-time corrections to the digital signal. With a 12 -bit resolution, 200 M sampling rate, and $\mathbf{9 0 \%}$ FSR sinusoidal input, the calibrated ADC link achieved an SFDR of $\mathbf{7 8. 2} \mathbf{~ d B c}$ and a THD of $\mathbf{- 8 2. 3} \mathbf{~ d B c}$, improving performance by 8% and 14% respectively. Nonlinear error fluctuations were also reduced by $\mathbf{3 0 \%}$, significantly mitigating harmonic interference.