COMPACT HIGH PERFORMANCE ANALOG CMOS BASEBAND DESIGN SOLUTIONS FOR
MULTISTANDARD WIRELESS TRANSCEIVERS

a novel compact wireless radio transceiver architecture
reusing a baseband chain so as to signi ficantly reduce the die area is proposed.The
proposed architecture employs a direct conversion architecture with a shared base-
band chain and is suitable for wireless standards based on time-division duplexing air
interface.In direct conversion architectures,baseband channel selection filters and
variable gain ampli fiers are placed in the receive path as well as in the transmit path.
Here,it is proposed to use the same baseband filters and variable gain ampli fiers in
both the receive path and the transmit path to reduce the die area.
To realize a high performance direct conversion receiver for multistandard
wireless communications,the limiting factors in the direct conversion receiver should
be identi fied and removed.In this dissertation,among many problems in direct
conversion receivers,the DC o ffset problem is addressed.The origins of the DC
o ffset are summarized,and three self-mixing mechanisms generating the DC o ffset
are modeled to understand how the static and dynamic DC o ffsets are produced from
the mechanisms.A DC o ffset cancellation scheme consisting of a static DC o ffset
canceller and a dynamic DC o ffset canceller is proposed.For the static DC o ffset
canceller,a DC feedback loop is proposed to use and veri fied through simulation,
fabrication,and measurement.A novel dynamic DC o ffset canceller utilizing an
adaptive filtering technique is also proposed and veri fied through simulation.


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