A Bandwidth-Enhanced Differential LC-Voltage Controlled Oscillator (LC-VCO) and Superharmonic Coupled Quadrature VCO for K-Band Applications
Beijing Key Laboratory of Radio Frequency IC Technology for Next Generation Communications, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China
Institute of Microelectronics, University of Chinese Academy of Sciences, 19A Yuquan Rd., Shijingshan District, Beijing 100049, China
COMSATS University, Wah Campus, G. T. Road, Wah Cantt 47040, Pakistan
Author to whom correspondence should be addressed.
Received: 29 June 2018 / Revised: 17 July 2018 / Accepted: 20 July 2018 / Published: 25 July 2018
A novel varactor circuit exhibiting a wider tuning range and a new technique for quadrature coupling of LC-Voltage Controlled Oscillator (LC-VCO) is presented and validated on a 25 GHz oscillator. The proposed varactor circuit employs distribute-biased parallel varactors with a series inductor connected at both ends of the varactor bank to extend the tuning range of the oscillator. Similarly, the quadrature coupling is accomplished by employing the 2nd harmonic, explicitly generated in the stand-alone free-running differential oscillator using frequency doubler. As an example, the Differential VCO (DVCO) is tunable between 20 GHz and 31 GHz and exhibits the best Phase Noise
of −100 dBc/Hz at 1 MHz offset frequency. Similarly, the Quadrature VCO (QVCO) covers 42% tuning bandwidth around 25 GHz oscillation frequency, which is significantly wider than other state-of-the-art VCOs at comparable frequencies. In addition, all the oscillators are designed in class-C to further improve their performances both in term of low power and low phase noise. The presented oscillators are designed using high-performance SiGe HBTs of the GlobalFoundries (GFs) 130 nm SiGe BiCMOS 8HP process. The presented DVCO and QVCO draw currents of approximately 10 mA and 21 mA, respectively from a 1.2 V supply.
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Ullah, F.; Liu, Y.; Li, Z.; Wang, X.; Sarfraz, M.M.; Zhang, H. A Bandwidth-Enhanced Differential LC-Voltage Controlled Oscillator (LC-VCO) and Superharmonic Coupled Quadrature VCO for K-Band Applications. Electronics 2018, 7, 127.
Ullah F, Liu Y, Li Z, Wang X, Sarfraz MM, Zhang H. A Bandwidth-Enhanced Differential LC-Voltage Controlled Oscillator (LC-VCO) and Superharmonic Coupled Quadrature VCO for K-Band Applications. Electronics. 2018; 7(8):127.
Ullah, Farman; Liu, Yu; Li, Zhiqiang; Wang, Xiaosong; Sarfraz, Muhammad M.; Zhang, Haiying. 2018. "A Bandwidth-Enhanced Differential LC-Voltage Controlled Oscillator (LC-VCO) and Superharmonic Coupled Quadrature VCO for K-Band Applications." Electronics 7, no. 8: 127.
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