Recently, Professor Yufeng Guo and Zhikuang Cai from National and Local Joint Engineering Laboratory of RF Integration and Micro-Assembly Technology and the College of Integrated Circuit Science and Engineering at Nanjing University of Posts and Telecommunications (NJUPT), in collaboration with Professor Pui-In Mak from University of Macau, has achieved a research progress in fast startup crystal oscillators (XOs). The relevant findings were published under the title A 16-MHz Crystal Oscillator with 17.5-μs Startup Time under 104-ppm-∆F Injection Using Automatic Phase-Error Correction in the international academic journal IEEE Journal of Solid-State Circuits, JSSC.
Professor Zhikuang Cai from the College of Integrated Circuit Science and Engineering at NJUPT and Professor Pui-In Mak from University of Macau are the corresponding authors. Associate professor Zixuan Wang is the first author, and the postgraduates Xin Wang and Yunjin Yin from the College of Integrated Circuit Science and Engineering are the co-authors of the paper. This is the first time that NJUPT has published a paper in JSSC.
In recent years, the wide application of 5G communication and Internet of Things systems has put forward high requirements for the startup speed of XOs. The constant frequency injection is recognized as the most effective technique to accelerate XO start-up. However, it suffers from the high cost of injection trimming and low chip yield caused by the narrow injection frequency offset tolerance, which hindered its promotion and commercialization.
To solve the above problem, the team proposed a single-ended injection technology based on automatic phase-error correction, and introduced negative feedback to real-time calibration of injection phase, which fundamentally overcame the influence of injection frequency offset on startup speed. The chip was fabricated in a 40nm CMOS process, and the experimental results show that its startup time is less than 19μs in the range of injection frequency offset of ±104 ppm, breaking the conventional tolerance limitation of 5000ppm. The results of multi-chip (30pcs) test show that the number of effective samples using unilateral injection technology is 69% higher than that using traditional injection technology in the voltage range of 0.95~1.05V. The injection technology proposed by the team greatly improves circuit robustness and chip yield, which is of great significance for promoting the application of injection technology and the commercialization of fast start XOs. The research was supported by the National Key Research and Development Program and the National Natural Science Foundation of China.
（Written by Zixuan Wang, Initially Reviewed by Zhikuang Cai Edited by Cunhong Wang, Reviewed by Feng Zhang）
