A 10-bit 1 MS/s 3-step ADC with bitstream-based sub-DAC and sub-ADC calibration

A 3-step Nyquist-rate ADC is presented which makes use of bitstream techniques to design and calibrate the D/A subconverter, while using the same hardware to calibrate the A/D subconverter. The novel methods presented remove the dependence on offsets and component mismatches in the D/A subconverter. They eliminate the need for a reference ladder in the A/D subconverter and calibrate comparator offsets. In addition, DC offsets in the residue amplifier are calibrated. Simulation results of a prototype in 0.18 μ CMOS technology show 10 bits of resolution at an operating speed of 1 MS/s.