A high output power and low phase noise GaN HEMT VCO with array of switchable inductors

Hsuan Ling Kao*, Chih Sheng Yeh, Hsien Chin Chiu, Cheng Lin Cho, Chun Hu Cheng

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


This paper presents cross-coupled voltage-controlled oscillators (VCOs) involving array of switchable inductors (i.e., N = 1 and N = 2 switchable inductors) and implemented using gallium-nitride high electron mobility transistors on Si substrate technology for worldwide interoperability for microwave access applications. Band selection and coarse frequency tuning were achieved using the array of switchable inductors, whereas fine tuning was controlled using varactors. Two bands were obtained using the one-stage switchable inductor VCO operating in the ranges 3.41–3.57 GHz and 3.85–3.94 GHz. The VCO output power (Pout) was 21.8 dBm at 3.57 GHz from a 10-V power supply. Four continuous bands were obtained using the two-stage switchable inductors VCO operating in the range of 3.16–3.4, 3.25–3.64, 3.48–3.71 and 3.64–3.9 GHz, respectively. An additional band was generated by fine-tuning the inductance through mutual coupling between the transmission line and one of the inductors. The proposed two-stage switchable inductors VCO provided a 21% tuning range at frequencies ranging with a control voltage ranging from 12 to 20 V, a low phase noise of −123 dBc/Hz at a 1-MHz offset from a 3.3-GHz carrier and a Pout of 21 dBm at 3.5 GHz from a 10-V power supply.

Original languageEnglish
Pages (from-to)1621-1636
Number of pages16
JournalInternational Journal of Circuit Theory and Applications
Issue number11
Publication statusPublished - 2017 Nov


  • GaN-on-Si
  • output power
  • phase noise
  • switchable inductor
  • tuning range
  • voltage-controlled oscillator

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Applied Mathematics


Dive into the research topics of 'A high output power and low phase noise GaN HEMT VCO with array of switchable inductors'. Together they form a unique fingerprint.

Cite this