Low-Overhead Self-Healing Methodology for Current Matching in Current-Steering DAC

In this brief, a low-overhead self-healing method for current matching in current-steering digital-to-analog converters (CS-DACs) is demonstrated. In contrast to traditional calibration methods that adjust current values, a statistical element selection (SES) algorithm optimizes the selection of unary current cells via combinatorial redundancy. This SES-based self-healing method relaxes the matching requirements for the current source array and achieves high static linearity at a minimum overhead cost of one current comparator and one digital controller. Moreover, this proposed low-overhead method is fully compatible with other segmented CS-DAC designs. A 14-bit CS-DAC design with on-chip self-healing control loop was implemented in 130-nm CMOS technology to demonstrate the proposed approach. The core area of the prototype chip was measured as 0.9 mm(2), with less than 0.1 mm(2) occupied by the current source array. After self-healing, the INLmax was measured as 0.64 least significant bit and spurious-free dynamic range was 85 dB for a 2-MHz input signal at 200-MS/s sampling rate.