Analytical and Experimental Study of Wide Tuning Range mm-Wave CMOS LC-VCOs

The unprecedented interest in high bandwidth applications in the mm-wave range has set off a wave of research exploring techniques that enable wide tuning range voltage-controlled oscillators (VCOs). Low frequency CMOS LC-VCOs (
${<} 10$
GHz) have been well studied in the literature and several approaches have been developed to optimize their performance. However, there lie several interesting challenges in the mm-wave space, specifically close to the
$f_T/f_{\max}$
, that motivate the need for analyzing the tuning range and phase noise in mm-wave VCOs. This paper presents a detailed analysis of the ultimate performance bound in simultaneously achieving low phase noise and wide tuning range in CMOS VCOs. The analysis is conducted on a 130 nm CMOS process, and confirmed by measurement results on three VCOs at 26 GHz, 34 GHz and 40 GHz. Finally, the impact of CMOS technology scaling (from 130 nm down to 45 nm), on the achievable performance bounds is analyzed and presented.