Analysis of voltage controlled oscillator

• Main Author: Nguyen, Huy Thong.
• Other Authors: Boon Chirn Chye
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Electronic circuits
• Online Access: http://hdl.handle.net/10356/54483
• Institution: Nanyang Technological University

In this report, the design of Voltage Controlled Oscillator (VCO) is presented. Fundamental principles, phase noise and mechanisms of which noise converted into phase noise in VCO are discussed. Two important theories on phase noise are elaborated. One approach is based on Time Linear Invariant model, while the other theory is established on Time Linear Variant. The later model takes into account the time variance nature of the periodical signal to derive the phase noise of an oscillator, proposed the very important concepts of Impulse Sensitivity Function and impact of Noise current modulation. The Voltage Controlled Oscillator is designed for ISM frequency bands, Blue Tooth (2.40GHz—2.48GHz), or IEEE 802.11b,g(2.40GHz–2.48GHz for Europe and USA). It employs the NMOS cross-coupled structure. The simulation results show that the VCO consumes 1.8mW, tuning range from 2.40-2.48 GHz, and phase noise performance of -121 dBc/Hz @ 1MHz frequency offset. Figure of Merit of the design is calculated to be 186. Quadrature VCO is required for the direct conversion and image rejection transceivers. Recent developments of QVCO are reported. The biggest contribution of this project is the design of a novel structure for quadrature signal generation. The proposed topology consumes 3.8mW per oscillator, tuning range from 2.42-2.48 GHz, and phase noise performance of -130.5 dBc/Hz @ 1MHz frequency offset. Figure of Merit of the design is achieved at 192.5. This is among one of the highest FOM for QVCOs in literature, to be the best of the author’s knowledge.