All-digital process-variation-calibrated timing generator for ATE with 1.95-ps resolution and maximum 1.2-GHz test rate

In this paper, an all-digital process-variation-calibrated high-performance timing generator for an automatic test equipment is proposed. The proposed timing generator generates process-variation-tolerant variable delays for high and wide-range testing clock frequency. In order to increase the testing clock frequency, a channel of the proposed timing generator consists of four subtiming generators operating in parallel. In addition, to improve process variation robustness, a precise eight-phase generator consisting of an accurate reference generator and a phase generator with dual-loop calibration (CAL) is proposed, and a phase error of less than 1.21° is achieved. Dynamic and static CAL techniques are also adopted in the edge vernier. A prototype chip having eight channels is fabricated using 0.13-μm CMOS technology. The proposed timing generator has an arbitrary test cycle frequency of up to 1.2 GHz, a timing resolution of 1.95 ps, a power consumption of 90 mW, and an area of 1.5 mm².