Low-Voltage Quadrature Voltage-Controlled-Oscillator Using Twisted Transformer
Sheng‐Lyang Jang, Yi-Ping Hsieh, Miin‐Horng Juang, Jiun-Yu Sung, Wen‐Cheng Lai · IEEE Microwave and Wireless Technology Letters · 2024
For low supply voltage operation, the voltage-controlled oscillator (VCO) with low voltage swing is subject to the injection pulling effect. This letter presents a low-voltage CMOS four-phase VCO using two differential LC VCOs coupled by two cross-coupled transformers. The proposed oscillator mitigates the injection-pulling effect by the 8-shaped transformers with two lobes. The transformers cancel the interference noise coupling and offer a drain-to-source transformer feedback to swing the source voltage to below ground level and to increase the voltage swing. The die area of the quadrature voltage-controlled oscillator (QVCO) in the TSMC 0.18$\mu $m BiCMOS process is 1.2$\times$0.963 mm$^{2}$. At the supply of 0.49 V, the oscillation frequency of the QVCO is 4.49 GHz and the figure of merit (FOM) is$-$187.032 dBc/Hz.