Analysis and Design of a Multi-Core Oscillator for Ultra-Low Phase Noise

S. A. R. Ahmadi-Mehr, M. Tohidian, R. B. Staszewski

Research output: Contribution to journalArticleScientificpeer-review

37 Citations (Scopus)
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In this paper, we exploit an idea of coupling multiple oscillators to reduce phase noise (PN) to beyond the limit of what has been practically achievable so far in a bulk CMOS technology. We then apply it to demonstrate for the first time an RF oscillator that meets the most stringent PN requirements of cellular basestation receivers while abiding by the process technology reliability rules. The oscillator is realized in digital 65-nm CMOS as a dualcore LC-tank oscillator based on a high-swing class-C topology. It is tunable within 4.07-4.91 GHz, while drawing 39-59 mA from a 2.15 V power supply. The measured PN is -146.7 dBc/Hz and -163.1 dBc/Hz at 3 MHz and 20 MHz offset, respectively, from a 4.07 GHz carrier, which makes it the lowest reported normalized PN of an integrated CMOS oscillator. Straightforward expressions for PN and interconnect resistance between the cores are derived and verified against circuit simulations and measurements. Analysis and simulations show that the interconnect resistance is not critical even with a 1% mismatch between the cores. This approach can be extended to a higher number of cores and achieve an arbitrary reduction in PN at the cost of the power and area.
Original languageEnglish
Pages (from-to)529-539
Number of pages11
JournalIEEE Transactions on Circuits and Systems Part 1: Regular Papers
Issue number4
Publication statusPublished - 11 Mar 2016


  • CMOS integrated circuits
  • LC circuits
  • MMIC oscillators
  • field effect MMIC
  • network analysis
  • network synthesis
  • phase noise
  • RF oscillator
  • current 39 mA to 59 mA
  • digital CMOS technology
  • dualcore LC-tank oscillator
  • frequency 4.07 GHz to 4.91 GHz
  • high swing class-C topology
  • multicore oscillator
  • phase noise reduction
  • ultralow phase noise
  • voltage 2.15 V
  • Inductance
  • Inductors
  • Phase noise
  • Power demand
  • Topology
  • Basestation (BTS)
  • LC-tank
  • class-C oscillator
  • coupled oscillators
  • figure of merit (FoM)

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