Phase-noise reduction of X-band push-push oscillator with second-harmonic self-injection techniques

To Po Wang*, Zuo-Min Tsai , Kuo Jung Sun, Huei Wang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


A low phase-noise X-band push-push oscillator using proposed feedback topology is presented in this paper. The oscillator core was implemented in a 0.18-μm CMOS process. By using a power splitter and a delay path in the feedback loop connecting the output and current source of the oscillator, a part of the oscillator output power injects to the oscillator itself. With the proper phase delay in the feedback loop and high transconductance of the current source, a low phase-noise oscillator is achieved. The amplitude stability and phase stability are analyzed, the phenomena of the phase-noise reductions are derived, and the device-size selections of the oscillator are investigated. The time-variant function, impulse sensitivity function, is also adopted to analyze the phase-noise reductions of the second-harmonic self-injected push-push oscillator. These theories are verified by the experiments. This self-injected push-push oscillator achieves low phase noise of -120.1 dBc/Hz at 1-MHz offset from the 9.6-GHz carrier. The power consumption is 13.8 mW from a 1.0-V supply voltage. The flgure-of-merit of the oscillator is -188.3 dBc/Hz. It is also the first attempt to analyze the second-harmonic self-injected push-push oscillator.

Original languageEnglish
Pages (from-to)66-76
Number of pages11
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number1
StatePublished - 1 Jan 2007


  • Current source
  • Delay line
  • Flgure-of-merit
  • High-Q resonator
  • Self-injection

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