Improvement of LC Oscillators Phase Noise by Using N-Path Filters

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Bayazi, Mohammad | 2017

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 50163 (05)
University: Sharif University of Technology
Department: Electrical Engineering
Advisor(s): Kavehvash, Zahra; Atarodi, Mojtaba
Abstract:
A novel low noise quadrature voltage-controlled oscillator (QVCO) with differential N-path filter is proposed in 0.18-μm CMOS technology. The said QVCO benefits from a cross-coupled structure and a current-reuse technology to produce the quadrature signal and to save power consumption and area, respectively. The new architecture reduces the phase noise by 8dBc/Hz at a 1MHz offset frequency for 2.4GHz oscillation frequency. QVCO consumes 9.8mW from 1.8V power supply when operating at 2.4GHz. QVCO has a frequency tuning range from 2.4GHz to 3GHz and achieves a FOM of 191dB at 1MHz offset. Switches of N-path filter are controlled by outputs of QVCO, so the center frequency of N-path filter is always equal to the oscillation frequency. Applying the two 4-path filters enhances Q of LC tank and therefore phase noise improves. In this new method, a differential N-path filter is used, thus capacitance consumption and chip area are reduced and because of using QVCO, no divide by 2 circuit is required
Keywords:
Phase Noise ; LC Tank ; Oscillators ; Filters ; N-Path Filter ; Quadrature Oscillator ; Complementary Metal Oxide Semiconductor Technology (CMOS) ; Terahertz Trancievers

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