A quadrature RC-oscillator with capacitive coupling

João Casaleiro, Luís B. Oliveira, Igor M. Filanovsky

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


In this paper the capacitive coupling in quadrature RC-oscillators is investigated. The capacitive coupling has the advantages of being noiseless with a small area penalty and without increasing the power dissipation. The results show that a phase error below 1° and an amplitude mismatch lower than 1% are obtained with a coupling capacitance about 20% of the oscillators capacitance value. Due to this kind of coupling, the phase-noise improves by 3 dB (to -115.1 dBc/Hz @ 10 MHz) and the increase of power requirement is only marginal leading to a figure-of-merit of -154.8 dBc/Hz. This is comparable to the best state-of-the-art RC-oscillators, yet the dissipated power is about four times less. We present calculations of frequency, phase error and amplitude mismatch that are validated by simulations. The theory shows that phase error is proportional to the amplitude mismatch, indicating that an automatic phase error minimization based on the amplitude mismatches is possible. The measurements on a 2.4 GHz voltage-controlled quadrature RC-oscillator with capacitive coupling fabricated in 130 nm CMOS circuit prototypes validate the theory.

Original languageEnglish
Pages (from-to)260-271
Number of pages12
JournalIntegration, the VLSI Journal
Publication statusPublished - Jan 2016


  • Capacitive coupling
  • Coupled oscillators
  • Quadrature oscillator
  • RC-oscillators
  • Van der Pol oscillators

Fingerprint Dive into the research topics of 'A quadrature RC-oscillator with capacitive coupling'. Together they form a unique fingerprint.

Cite this