Quadrature VCO Via Transformer-coupled Transmission Line

Abstract

This paper presents a new quadrature voltage-controlled oscillator (QVCO), which consists of four cross-coupled voltage-controlled oscillators (VCOs) coupled by a loop inductor through magnetic coupling. The circuit design uses the concept of traveling wave and standing wave oscillators. The proposed CMOS QVCO has been implemented with the TSMC 0.18$\mu$ m SiGe 3P6M technology and the die area is 1. $072 \times 1$. 072mm2. At the supply voltage of 1V, the total power consumption is 5.33mW. The free-running frequency of the QVCO is tuneable from 3.26 GHz to 3.98 GHz as the tuning voltage is varied from 0.0V to 2V. The measured phase noise at 1MHz frequency offset is-122.143 dBc/Hz at the oscillation frequency of 3.26 GHz and the Figure of merit (FOM) of the proposed QVCO is-185.11 dBc/Hz.