A wide band differentially switch-tuned CMOS monolithic quadrature VCO with a low Kvco and high linearity

Abstract

A wide band, differentially switch-tuned CMOS monolithic LC–VCO is presented in this paper, as well as a frequency divider for high linearity, low Kvco quadrature signal generation. A linearity control logic is proposed. The Kvco linearity is improved to be lower than 17.68MHz/V. By using the proposed CML DFF, the operating frequency of the frequency divider is increased by 20% with a power consumption of 3.6mW. The proposed design has been fabricated and verified in a 0.18μm CMOS process. The QVCO is tuned in a combined way of continuous technology and 4bit binary switch capacitor array (SCA) discrete tuning technology. The measurement indicates that the QVCO has a 19.7% tuning range from 1.816 to 2.213GHz. The measured phase noise is −112.25dBc/Hz at 1MHz offset from the 1.819GHz carrier and draws a current of 4.0mA around at a 1.8V supply.