Ultra wide Tuning Range and Low Phase Noise mm-Wave LC VCOs
Over the past few years, there has a been a growing
demand for mm-wave circuits with emerging applications such as Gigabit WLAN and Short Range Radars. More recently, mm-wave technology has been touted for future 5G cellular systems, eclipsing a long era where low GHz systems dominated the field of wireless systems. Moving forward, we expect the mass market adaptation of these technologies to force the shift towards low-cost Si-based processes. However, in order to succeed in this space, we need to push the Si performance closer to the well-entrenched incumbent III-V technologies. In the VCO domain, major challenges still remain in meeting the tuning range and phase noise specifications while maintaining high yield.
In light of these challenges, this research is focused on building mm-wave VCO circuits with record benchmarks. Different topologies in both CMOS and SiGe technologies were developed. Advanced techniques such as active tunable negative capacitance are utilized to break fundamental barriers in silicon based technologies. These new architectures were presented in 2012 IEEE Compound Semiconductor IC Symposium (CSICS), 2013 Transactions on Circuits and Systems - II (TCAS-II) and 2013 IEEE Radio Frequency Integrated Circuits Symposium (RFIC).
The research also takes an in-depth analysis of phase noise at mm-wave frequencies and proposes a new VCO architecture that incorporates inductance redistribution and BiCMOS cross-coupled pairs with current redistribution to achieve record figure-of-merits (FoM/FoMT). Results from this research were highlighted in 2013 IEEE International Solid State Circuits Conference (ISSCC).
Moreover, a new analytical model that facilitates an efficient optimization of the VCO tuning range and phase noise was developed. The model is also exploited to analyse the impact of CMOS technology scaling on the achievable performance bounds. This analytical model was published in 2013 IEEE International Symposium on Circuits and Systems (ISCAS) and 2014 EEE Transactions on Circuits and Systems - I (TCAS-I).
Students Involved: S. Alzahrani, M. Belz, S. Rashid