A High Timing Resolution and Data Rate Pulse Generator for Automatic Test Equipment Applications

Arbitrary waveform generators (AWGs) and algorithmic pattern generators (ALPGs) typically adopt the functionality achieved by combining multiple pulse generators (PGs). If the data rate and timing resolution of a single PG can be efficiently improved, using multiple PGs will result in a multiplicative increase in performance. The 2-Gb/s PG with a timing resolution of 1.97 ps has been designed. The proposed PG uses an edge combiner (EC) and a phase-locked loop (PLL). The EC provides a programmable waveform with a timing interval of 1.97 ps and employs a counter scheme and an MOS varactor to define the operational data rate range and timing resolution. To combine the period window (WIN) with the PLL output, the EC uses the WIN controller, which incorporates a count-up counter, to enable a wide operational range. The WIN controller operates with only one WIN to simplify its sampled circuit. The timing resolution of the coarse-tuning stage (CTS) was determined from the PLL period. The fine-tuning stage (FTS) introduces an auto-calibration circuit to achieve high timing resolution. This auto-calibration technique ensures consistent timing resolution and tuning range under process, voltage, and temperature (PVT) variations. The digital-type calibration scheme can achieve low power consumption. In addition, a replica delay line scheme is proposed to compensate for the tuning range of the FTS, thereby enabling the PG to maintain high-accuracy waveforms under PVT variations. For the high timing resolution, the proposed MOS varactor with a digital-to-analog converter DAC (MOS-DAC) in FTS is adopted to achieve multibit control for timing resolution, thereby reducing the number of stages in the delay line and minimizing power consumption. The test chip was fabricated using a 90-nm CMOS process, with a core area of $215\times 367~\mu $ m2 and power consumption of less than 10.55 mW. The data rate range of the PG spanned from 977.6 kb/s to 2 Gb/s, and the timing resolution and average accuracy were 1.97 ps and ±1.18 least significant bit (LSB), respectively. Therefore, a well-designed PG is highly beneficial for automatic test equipment (ATE) systems.