A low-power 12-phase single capacitively coupled ring VCO for wideband N-path systems

Abstract

This work presents a novel Single Capacitively Coupled (SCC) ring Voltage-Controlled Oscillator (VCO) designed for wideband N-path systems. It reduces the number of capacitors by half compared to the Double Capacitively Coupled (DCC) design, potentially requiring less silicon area while maintaining improved phase noise performance compared to the pseudo differential ring VCO, and with less power consumption than the DCC design. The proposed SCC VCO, tunable from 0.3 to 3.0 GHz, achieves the lowest power consumption among the state-of-the-art designs compared, consuming just 0.48 mW at 3 GHz, with a phase noise of -76.5 dBc/Hz at 1 MHz offset. Consequently, the figure of merit (FOM) remains modest at -147 dBc/Hz, comparable to other designs but leaving room for improvement. The analysis reveals that improper configuration may lead to unwanted oscillation modes of the three VCOs analyzed, making a startup circuit essential for stable operation. These results position the SCC ring VCO as a promising candidate for low-power, high-performance applications.