Low Noise Distributed Amplifiers In Broadband Communication Systems
Distributed amplifiers have long been utilized to extract useful gain from an active device technology over extreme bandwidths. The distributed topology is well suited to delivering gain over larger bandwidths than other circuit techniques by breaking the gain-bandwidth tradeoff and replacing it with a gain-delay tradeoff. For bandwidths approaching the transition frequency (fT) of the active device technology employed, the distributed amplifier has lower noise figure than alternative techniques. This dissertation explores the region of the design space where distributed amplifiers are the best choice and reveals several new techniques for achieving improved noise and gain compared with conventional distributed techniques. The blue-noise active termination (BNAT) is a hybrid active-passive low-noise termination uniquely tailored to exploit the bi-directional propagation characteristic of the distributed amplifier to remove the effect of one of the amplifier's primary noise sources. This results in significant improvement in low frequency noise figure. Also, type filter sections are shown to be superior to conventional T-type sections as the building blocks of monolithically integrated distributed amplifiers. type sections give higher gain and lower noise in less area for the same bandwidth than would be possible using T-type sections. Finally, enhancement of the distributed amplifier's dispersion characteristic is demonstrated which opens the door for applications as a dispersive delay line in analog signal processing and time-domain communication schemes.
distributed amplifier; low noise amplifier
Apsel, Alyssa B.
Afshari, Ehsan; Lipson, Michal
Ph. D., Electrical Engineering
Doctor of Philosophy
dissertation or thesis