Design of high-Q varactors for low-power wireless applications using a standard CMOS process

New applications such as wireless integrated network sensors (WINS) require radio-frequency transceivers consuming very little power compared to usual mainstream applications, while still working in the ultra-high-frequency range. For this kind of applications, the LC-tank-based local oscillator remains a significant contributor to the overall receiver power consumption, This statement motivates the development of good on-chip varactors available in a standard process, This paper describes and compares the available solutions to realize high-e, highly tunable varactors in a standard digital CMOS submicrometer process. On this basis, quality factors in excess of 100 at 1 GHz, for a tuning ratio reaching two, have been measured using a 0.5-mu m process.