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A fully integrated push–push voltage controlled oscillator (VCO) working in K-band with a large tuning range and a low phase noise fabricated in a 0.18 μm SiGe BiCMOS technology is presented. Multi-coupled LC tanks are used to improve the tuning range, power consumption and phase noise. Digital tuning varactors are used to maintain a low VCO tuning sensitivity (K_VCO) and maximum frequency overlap. The VCO achieves a frequency tuning range (FTR) of 17% at 12 GHz, a phase noise of -106.62 dBc/Hz at 1 MHz offset and consumes 7 mW from 1.8 V supply.

In this paper, a fully integrated Ku-band voltage controlled oscillator (VCO) with low phase noise is presented in a GaAs heterojunction bipolar transistor (HBT) technology. A cross-coupled configuration is employed to achieve low phase noise, and to achieve high output power, the largest HBT and higher bias current are adopted. The implemented VCO demonstrates that the oscillation frequency is from 13.77GHz to 14.8GHz, with a maximum 4.83dBm output power at 13.77GHz. The phase noise of the VCO is $-$100.2dBc/Hz at 1MHz offset from 14.36GHz oscillation frequency. The VCO consumes 61.2mW from 6V supply and occupies an area of 0.51mm$\times 0.62$mm. Finally, the figure-of-merits (FOMs) for VCOs are discussed.

In this work, a novel circuit structure for second-harmonic multi-phase voltage controlled oscillator (MVCO) is presented. The proposed MVCO is composed of $N$ ($N$ being an integer number and $N\ge$2) identical inductor–capacitor ($LC$) tank VCOs. In theory, this MVCO can provide 2$N$ different phase sinusoidal signals. A six-phase VCO based on the proposed structure is designed in a TSMC 0.18um CMOS process. Simulation results show that at the supply voltage of 0.8V, the total power consumption of the six-phase VCO circuit is about 1mW, the oscillation frequency is tunable from 2.3GHz to 2.5GHz when the control voltage varies from 0V to 0.8V, and the phase noise is lower than $-$128dBc/Hz at 1MHz offset frequency. The proposed MVCO has lower phase noise, lower power consumption and more outputs than other related works in the literature.

In this paper, a full PMOS Colpitts quadrature voltage-controlled oscillator (QVCO) topology, suitable for low supply voltage and low power dissipation, is presented. For an enhanced voltage swing under a low supply voltage, the capacitive-feedback technique is employed. Quadrature coupling is achieved by employing direct bulk coupling technique, leading to reduction in both power and chip area. The proposed QVCO covers a 5% tuning range between 2.325 GHz and 2.435 GHz, and the phase noise is $-$128.2 dBc/Hz at 1-MHz offset from the 2.34-GHz carrier while consuming only 0.535 mW from 0.55-V supply voltage, yielding a figure-of-merit (FoM) of 198 dBc/Hz.

The differential ring voltage controlled oscillator (VCO) is one of the critical devices in wireless communication system having excellent stability, controllability and noise rejection ability. A novel design of delay cell is proposed for the four staged CMOS differential ring VCO with high output frequency, low power consumption and low phase noise. The differential ring VCO utilizes multiloop dual delay path topology to acquire both high output frequency and low phase noise. Results have been achieved in TSMC 0.18-$\mu$m CMOS process with a supply voltage ($V_{dd}$) 1.8V. The proposed design achieves an output frequency range of 4.029GHz to 6.122GHz and power of 4.475mW is consumed with control voltage variation from 1V to 2V. The proposed VCO exhibits $-$89.7dBc/Hz phase noise at 1MHz offset frequency and the corresponding figure of merit (FoM) is $-$155.9dBc/Hz. The design of differential ring VCO with novel delay stage has improved performance in terms of power consumption, output oscillation frequency and phase noise.

An 11.8-GHz low-power, low phase noise, 65-nm CMOS LC-VCO for V2X communication standards is presented in this work. To achieve low-phase noise performance to fulfill the 5G NR C-V2X standards, several adjustments are made to the conventional LC-VCO topologies. These adjustments are briefly explained in this work. Presented VCO consumes 3.046mA current from a 1.2-V power supply. It has $-$116.13dBc/Hz phase noise at 1MHz offset and tuning range between 11.64GHz and 11.94GHz. A frequency divider circuit is designed and implemented to the presented VCO to satisfy the frequency spectrum of V2X radio access technologies. To the best of authors’ knowledge, this work is the first VCO implemented at 11.8 GHz in a 65-nm CMOS process with the reported phase noise number for 5G NR C-V2X applications.