A CMOS programmable self-calibrating 13-bit eight-channel data acquisition peripheral

A 13-b self-calibrating algorithmic A/D converter with sample and hold and eight-channel multiplexer has been implemented in a standard 3-μm CMOS technology. Digital circuitry including a sequencer, instruction RAM, and microprocessor interface have been incorporated to implement a complete data-acquisition peripheral. The conversion algorithm, calibration technique, and gain trimming circuitry are described. A bandgap voltage reference with buffered output and additional output voltage proportional to absolute temperature has also been implemented. Experimental data show that the integral and differential linearity meets 1/2 LSB (least significant bit) at the 13-b level; the dynamic performance is such that harmonic distortion of better than 84 dB below the fundamental is achieved.