Browsing by Subject "Phase noise"
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Item A dual-loop frequency synthesizer(2006-12) Karsani, Lalith; Chao, Kwong S.; Mitra, SunandaA dual-loop frequency synthesizer is proposed to reduce the phase noise introduced by the Voltage Controlled Oscillator (VCO) which is the main source of noise in a traditional PLL based frequency synthesizer. The focus of this thesis is on the analysis and simulation of the proposed dual-loop frequency synthesizer architecture and comparison of results with that of the standard frequency synthesizer. Instead of the traditional PLL based frequency synthesizer with single feedback loop from the VCO output through a divider back to the phase detector an additional feedback path from VCO output through a Frequency to Voltage Converter (FVC) to the input of the loop filter is introduced. Results show considerable improvement in the phase noise performance and the lock time. The improved performance can be attributed to noise suppression in the loop for reasons similar to a sigma-delta modulator. Due to this improved noise performance dual-loop frequency synthesizer is suitable for applications which require high phase noise suppression.Item An assessment of the GPS L5 signal based on multiple vendor receivers(2011-12) Smyers, Serena Ashley; Schutz, Bob E.; Kerkhoff, AaronThe L5 signal of the Global Positioning System (GPS) is becoming available on an increasing number of Block IIF satellites. As the third civilian signal, L5 is superior in signal design to the L1 C/A and L2C civilian signals. This new signal has been marked healthy for use on selected satellites since 2010, yet the hardware capable of tracking the L5 signal is still in the early stages of development. This work investigates the characteristics of the new signal and the quality of data produced by L5-tracking receivers. Commonly used receiver models chosen for this study are the Leica GRX1200+GNSS, the Trimble NetR8, and the Javad Delta TRE-G3TH. The metrics used in this analysis to assess the quality of data produced by these receivers are signal strength, receiver phase noise, receiver code noise, and multipath. The data used in these analyses were obtained from the International GNSS Service for the days of the year 275 to 281 in 2011. Metrics averaged over the GPS week 1656 provide a good indication of the overall performance of the receivers.Item Superharmonic Injection Locked Quadrature LC VCO Using Current Recycling Architecture(2011-02-22) Kalusalingam, ShriramQuadrature LO signal is a key element in many of the RF transceivers which tend to dominate today?s wireless communication technology. The design of a quadrature LC VCO with better phase noise and lower power consumption forms the core of this work. This thesis investigates a coupling mechanism to implement a quadrature voltage controlled oscillator using indirect injection method. The coupling network in this QVCO couples the two LC cores with their super-harmonic and it recycles its bias current back into the LC tank such that the power consumed by the coupling network is insignificant. This recycled current enables the oscillator to achieve higher amplitude of oscillation for the same power consumption compared to conventional design, hence assuring better phase noise. Mathematical analysis has been done to study the mechanism of quadrature operation and mismatch effects of devices on the quadrature phase error of the proposed QVCO. The proposed quadrature LC VCO is designed in TSMC 0.18 ?m technology. It is tunable from 2.61 GHz - 2.85 GHz with sensitivity of 240 MHz/V. Its worst case phase noise is -120 dBc/Hz at 1 MHz offset. The total layout area is 1.41 mm^2 and the QVCO core totally draws 3 mA current from 1.8 V supply.