Ku-Band Low Phase Noise VCO Using High-Quality Factor Transformer in 0.18-μm CMOS Technology

• Published in: IEEE microwave and wireless components letters 2022-10, Vol.32 (10), p.1207-1210
• Main Authors: Mansour, Islam, Mansour, Marwa, Aboualalaa, Mohamed, Allam, Ahmed, Abdel-Rahman, Adel B., Pokharel, Ramesh K., Abo-Zahhad, Mohammed
• Format: Article
• Language: English
• Subjects: Broadband; CMOS; Inductance; Inductors; Ku-band; Metal oxide semiconductors; Phase noise; phase noise (PN); Q-factor; Switches; transformer; Transformers; Voltage controlled oscillators; voltage-controlled-oscillator (VCO); Wireless communication
• ISSN: 1531-1309; 2771-957X; 1558-1764; 2771-9588
• DOI: 10.1109/LMWC.2022.3167705

This work introduces a low phase-noise (PN) wideband voltage-controlled-oscillator (VCO) by proposing five ports transformer in 0.18- \mu \text{m} CMOS technology. The proposed VCO uses five ports transformer and operates in the low band when all the pMOS-nMOS cross-coupled VCO components are activated, whereas this VCO operates in the high band using only part of the transformer, and an nMOS cross-coupled core. The transformer is designed using the top metal layer (M6) and the first inductor is meander line U-shaped center tap inductor, while the second inductor consists of two shunted octagonal loops to increase the quality ( {Q} -) factor compared with using a single-loop inductor. The wideband switched transformer VCO achieves a measured frequency tuning range (FTR) of 16.4-17.1 GHz with a PN of −113.3 dBc/Hz at 1-MHz offset, and from 17 to 17.9 GHz with a PN of −110.3 dBc/Hz at 1-MHz offset in the low and high bands, respectively. The achieved figure-of-merit (FoM) is −189 and −186.4 dBc/Hz in the low and high bands, respectively.