A Tunable Impedance Wideband Low Noise Amplifier
Date Issued
2012
Date
2012
Author(s)
Lin, Jieh
Abstract
Low noise amplifier ( LNA ) is a critical component for ultrasound medical equipment, since it amplifies tiny echo signals reflected from tissues without adding much noise. Wideband input impedance match with the loading of ultrasound transducers is therefore important for LNAs to provide constant gain over a wide frequency range. State-of-the-art LNA for general applications is designed such that the impedance is matched with a specific impedance. To extend the capability of LNA to different transducers, which would lead to significantly lower cost, a wideband tunable input impedance of the amplifier is designed by varying bias current of the transistor, which is used to provide the system gain. Two prototypes amplifier are constructed to validate the proposed architecture with discrete HBT transistors and 0.35 μm CMOS process, respectively. And it has shown the small gain variation with a wide tuning range of input impedance from 30 to 90 Ohm. The measured noise figure is 7.33 dB with an average gain of 13.5 dB over the range of input impedance.
Subjects
LNA
tunable input impedance
Type
thesis
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ntu-101-R99525033-1.pdf
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