Systematic Design of Supply Regulated LC-Tank Voltage-Controlled Oscillators

• Published in: IEEE transactions on circuits and systems. I, Regular papers Vol. 55; no. 7; pp. 1834 - 1844
• Main Authors: Xuejin Wang, Bakkaloglu, B.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.08.2008; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: 1f noise; Circuits; CMOS; CMOS process; DC-DC power conversion; Design engineering; Frequency; Integrated circuit noise; Low-frequency noise; Noise; Noise levels; Noise reduction; Phase noise; Power supplies; power supply rejection (PSR); Pushing; Regulators; Voltage controlled oscillators; voltage regulators; voltage-controlled oscillators (VCOs); power supply rejection; DC-DC power conversion; voltage regulators; voltage controlled oscillators; phase noise
• ISSN: 1549-8328; 1558-0806
• DOI: 10.1109/TCSI.2008.918004

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-mum, 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.