An FPGA-Calibrated Modulo ADC for High-Dynamic-Range Signal Acquisition

Abstract

Conventional analog-to-digital converters (ADCs) suffer from irreversible clipping when input amplitudes exceed their fixed full-scale range. Modulo ADCs address this by folding the input signal prior to quantization; however, stable hardware operation under deep-folding conditions and experimental validation of algorithmic recoverability remain outstanding challenges. This paper presents a calibrated FPGA-based modulo ADC platform in which a finite state machine with multi-bit update control governs folding dynamics, replacing instantaneous comparator-triggered feedback to ensure deterministic and stable operation. A controlled under-compensation calibration strategy converts fold-dependent threshold mismatch and oscillatory instability into a bounded constant residual, enabling reliable folding at high folding depths. The platform achieves a dynamic range expansion exceeding two orders of magnitude while maintaining signal fidelity comparable to that of the standalone ADC. Experimental validation across diverse waveforms confirms robust signal acquisition and demonstrates the practical feasibility of dynamic-range extension using modulo sampling principles.