Mathcad - ee217projtodonew2.mcd

Introduction
Low noise amplifiers are useful for a variety of applications, where small signals are received.
This report is written specifically for the application in a IS-95B cellular telephone handset. The
routines developed to design an analyze the amplifier are organized in a way so that the design
process is completely automated after entry of the process parameters and high level system
specifications. Also the procedure is general purpose that keyu equations can be replaced so the
routine is suitable for other configurations and devices, such as GaAs and MOSFETs. After the
Mathcad automated design is complete, the results are used as a starting point for simulations on
a commercial simulation tool. The graphs of performance parameters as a function of device size
and current serve as a guideline for the iterations of simulations. The final simulated results for
amplifier are summarized and conclusions are made.
The low noise amplifier designed for this project is part of a larger project. The specifications
for the amplifier were developed for use in the handset of a 1900MHz CDMA cellular telephone.
The actual specifications involve trade-offs with blocks which occur later in the receiver chain. A
collection of more than 16 impedance matching routines were also developed in previous project
unrelated to the system analysis. These collection of routines are easily available on the
following website: http://www.eecs.berkeley.edu/~wetherel/rftoolbox/matcher.html. The
system analysis and the impedance matching network design routines were used as a
foundation for the automated low noise amplifier design tool.
An interesting comment on the report for this project is that it is written entirely in Mathcad, a
tool for simultaneuous word processing and mathematics computation. This combination of
features makes the report a "living" document. With a few clicks the reader can modify the LNA
design for his/her specific system and process specifications. In a world where processes
change every few years and new specifications are needed just as often the design automation of
LNAs is a very useful feature. The use of Mathcad also allowed the rapid entering of design
equations from available books on radio frequency circuit design. These equations include those
for simultaneous conjugate impedance matching [ ] and distortion analysis of common-emitter
amplifiers [ ].