analog baseband development
A great deal of effort in academia and industry has been made to meet the
ever-growing demands for low-cost, low-power, and single-chip transceivers for multistandard
wireless communications. The explosive growth in the mobile phone market
has fueled the transition from the second generation (2G) to the third generation
(3G), and the growing demand for wireless access to the Internet in buildings has
called for the development of wireless local area network (LAN) standards. Even
short range wireless communication devices for connecting peripherals to a computer
or speakers to an audio amplifier are in great demand recently. Therefore, to develop
a single-chip wireless transceiver working for as many wireless standards as possible
has been a challenging problem.
To reach the ultimate goal, the first step would be the choice of an appropriate
transceiver architecture for effectively processing the signal received at the antenna.
The right selection of the transceiver architecture is the key to success in developing a
multistandard single-chip wireless transceiver. The first objective of the dissertation
is to propose a novel wireless transceiver architecture which occupies a smaller area
and can work for many wireless standards. The proposed transceiver architecture is
especially designed for time-division duplexing systems.
Among many transceiver architectures, the direct conversion, also known as homodyne
or zero-IF, is the most attractive choice for multistandard wireless transceivers
because of its simplicity and suitability for monolithic integration as well as multistandard
operation [3]. Though the direct conversion architecture possesses many
preferable characteristics, it still has some critical drawbacks which should be mitigated
in order to be successfully implemented. The second objective of the dissertation
is to address the DC offset problem, which is one of the inherent problems in the
direct conversion architecture. In this dissertation, the DC offset generation mechanisms
are modeled and the DC offset cancellation methods for multistandard wireless
transceivers are discussed. A DC offset canceller which can track and cancel a fast
varying DC offset is also proposed. Here, adaptive filtering techniques are utilized to
cancel the fast varying DC offset.