Abstract

Systematic design of low-dropout-regulator (LDO) regulated low-phase-noise LC-tank voltage controlled oscillators (VCOs) is presented. Low-frequency sensitivity profile of power supply induced phase noise of a typical cross-coupled LC-tank VCO is investigated. The relationship between frequency pushing and power supply-induced phase noise is derived. Systematic codesign of VCO sensitivity to low-frequency supply noise with respect to an LDO output noise and power supply rejection profile is introduced. To demonstrate the design approach experimentally, two 2.4-GHz LC-tank VCOs with pMOS and nMOS switching devices powered by PFET LDOs are designed and fabricated on an 0.18-μm, 7-layer metal CMOS process. By using an integrated LDO, it is shown that the VCO phase-noise sensitivity to low frequency improves by 55 dB at 100-kHz offset.

Original languageEnglish (US)
Pages (from-to)1834-1844
Number of pages11
JournalIEEE Transactions on Circuits and Systems I: Regular Papers
Volume55
Issue number7
DOIs
StatePublished - Aug 1 2008

Keywords

  • DC-DC power conversion
  • Phase noise
  • Power supply rejection (PSR)
  • Voltage regulators
  • Voltage-controlled oscillators (VCOs)

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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