A signal-independent background-calibrating 20b 1MS/S SAR ADC with 0.3ppm INL

The SAR ADC is the architecture of choice for high-precision Nyquist ADCs (>16b) with MS/s speed. To achieve the required linearity performance, precision SAR ADCs require calibration to correct mismatch errors in the capacitive digital-to-analog converter (CDAC). One-time factory calibration suffers from aging, temperature sensitivity, and package and PCB stress while foreground calibration precludes continuous ADC operation. This paper presents a 20b 1MS/s SAR ADC with signal-independent background-calibration to address this challenge.