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Theoretical Analysis and Design Methodologies for Low Noise Amplifiers based on Tunable Matching Networks
Mustafa Berke Yelten
Date: 2008-06-26
Degree: MS - Electrical Engineering
Advisory Committee
Dr. Brian Hughes - Committee MemberDr. Kevin G. Gard - Committee Chair
Dr. Wm. Rhett Davis - Committee Member
Abstract
The low noise amplifiers (LNAs) have a big importance in the noise performance of the receiver structures for wireless communication devices. Various design procedures and design examples have been suggested for narrowband frequency applications. However, with the increase in the number of different standards in the wireless communication technologies, a rising demand for receiver topologies that will operate at multiple frequencies by preserving the noise, gain and linearity responses reached at a single frequency has been observed. One method to achieve this target is to employ tunable passive components in the circuit. Tunable components give the flexibility of changing the component value for a certain frequency band with a considerable quality factor. Recent studies indicate that various tunable components can be fabricated for radio frequency and microwave integrated circuits with which the design topologies for various building blocks can be converted into their tunable equivalents. This thesis considers the usage of tunable reactive components in the low noise amplifiers from the theoretical and design perspective. The implemented topologies are based on heterojunction bipolar transistors (HBTs) from the IBM 0.18 m BICMOS (7HP) design kit. The first part of this thesis considers the theoretical derivation of the quantities, the input impedance and optimum noise impedance, Zin and ZOPT, on which the low noise design principles are built. Subsequently, a design methodology that will be more suitable for tunable low noise amplifier application is developed based on the theoretical calculations presented in the previous part. To demonstrate the design procedure, a LNA operating at 5 GHz will be presented both with ideal and non-ideal reactive components. Then, the tunability aspect of the design procedure is investigated by building two more LNA structures operating at 1 GHz and 10 GHz whereby all passive components are assumed to be tunable. Considering the fact that tunable components actually add noise and nonlinearity to the design structures, a single component, the series matching capacitor is chosen to be the only tunable element in the circuit. The design at 5 GHz is repeated with this constraint and the range for which the noise and input matching characteristics are preserved is determined. It is possible to acquire 3 GHz of bandwidth (3.5 GHz to 6.5 GHz) where the noise figure of the design is very close to the minimum noise figure of the LNA (NF- NFmin
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