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This paper describes frequency-band selection/switching techniques
and their application to multi-mode wireless receiver circuits
for mobile terminals. These circuits utilize voltage-controlled
variable inductors and resistors for, changing input/output
impedance and load of the receiver's key-circuits in accordance
with each mode's frequency band. Preliminary results for several
0.18um-BiCMOS building block circuits including RF amplifiers
and up/down mixers show feasibility of the approach proposed
in multi-mode transceiver systems.
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Since the last decade, there has been a tremendous growth
in digital wireless communications with introduction of 2nd
generation of mobile phones. These systems are evolved from
1st generation analog systems and resulted to different standards
like PDC, GSM, IS-136, and IS-95 in different parts of the
world to provide high quality voice and low data rate services.
Diversity and incompatibility of these standards and needs
for higher data rates have been the major driving forces for
developing a uniform international standard, which is very
demanding and attractive for manufacturers, operators, and
end users. Along this target, the WCDMA standard has been
developed and adopted for 3rd generation cellular systems
in Japan and Europe, and cdma2000 in the USA. There are many
standards for wireless systems nowadays and the perspective
is that they will coexist for years. Therefore development
of a multimode/multi-standard/multi-band user terminal is
a necessity to achieve global roaming. This is the main reason
that concept of Software Defined Radio has received very high
attention as a pragmatic solution. In software implementation
of a user terminal, the air interface can be dynamically configured
based on the available radio environments.
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Realization of such system requires development of multi-mode
front-end modules capable of switching from one service operating
at a frequency to another service operating at another frequency.
A currently available multi-mode approach makes use of different
circuits for different modes and therefore does not meet low-cost
low-power small-size requirement. Another available approach
applies the same chip, but has an inter-mode multiple frequency
relation constraint. The present paper describes a multi-mode
approach in which a single-chipset can be unconditionally
reconfigured and used for different modes. Circuit topology,
design approach, and experimental results for a transceiver's
key-circuits developed in a 0.18um-BiCMOS technology are discussed.
Biography
Mohammad Madihian received the B.Sc. degree from Iran University
of Science and Technology in 1976, and the M.Sc. and Ph.D.
degrees from Shizuoka University, Japan, in 1980 and 1983,
respectively, all in electronic engineering.
In 1983, he joined NEC Central Research Laboratories, Kawasaki,
Japan, where he worked on research and development of GaAs
and Silicon device-based digital as well as microwave and
millimeter-wave monolithic IC's. In 1999, he moved to NEC
Laboratories America, Inc., Princeton, New Jersey, and is
presently the Head of Microwave & Signal Processing Department
where he conducts analog/RF front-end IC's and baseband processing
activities for high-speed wireless networks and personal communications
applications.
Dr. Madihian has received the IEEE MTT-S Best Paper Microwave
Prize in 1988, and IEEE Fellow Award in 1998. He has authored
or co-authored more than 130 scientific publications including
50 IEEE journal/conference papers, and holds 35 granted as
well as 30 pending patents on device and circuit applications.
He has served as Guest Editor to the IEEE Journal of Solid-State
Circuits and IEICE of Japan. Dr. Madihian is presently serving
on the IEEE GaAs IC Symposium Executive Committee, IEEE International
Microwave Symposium Technical Program Committee, IEEE MTT-6
Subcommittee, IEEE MTT Editorial Board, SSDM, and APMC. He
is on the Steering Committee of the upcoming IEEE 2003 Int.
Microwave Symposium (Philadelphia), and the Guest Editor to
Special Issue of IEEE MTT Transactions, December 2003.
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