CMOS Switched-Capacitor Circuits: Recent Advances in Bio-Medical and
RF Applications
When: Monday, October 31, 2011 - 4:00pm - 4:50pm
Where: KEC 1001
Speaker Information
Speaker Name: David J. Allstot
Speaker Title/Description:
Professor
Department of Electrical Engineering
University of Washington
Speaker Biography:
David J. Allstot received the B.S. from the Univ. of Portland, the
M.S. from Oregon State Univ. and the Ph.D. from the Univ. of
California, Berkeley. He has held several industrial and academic
positions and has been the Boeing-Egtvedt Chair Professor of
Engineering at the Univ. of Washington since 1999. He was Chair of the
Dept. of Electrical Engineering from 2004 to 2007. Dr. Allstot has
advised approximately 100 M.S. and Ph.D. graduates, published about
300 papers, and received several awards. He has also been active in
service to IEEE.
The switched-capacitor technique has been used in high-volume data
conversion and signal processing ICs for more than three decades. It
is also ubiquitous in RF transceiver circuits because it uses
capacitors, which are area-efficient native devices in CMOS
technologies, and MOSFETs operating as switches.
The RF power amplifier dissipates a large fraction of the total power
of a transceiver because of its low efficiency. Despite more than two
decades of intensive research, the challenge of on-chip RF PAs with
high efficiency in digital-friendly CMOS technologies has not been
met. Switching PA topologies with relatively high efficiency have
gained momentum, and relatively high output power is being delivered
using power combining techniques. Supply regulation techniques have
enabled higher efficiency when amplifying non-constant envelope
modulated signals. A new paradigm?the switched-capacitor RF power
amplifier?which meets many of the remaining challenges is described.
Body-area-networks (BAN) that integrate multiple sensor nodes in
portable and wearable bio-medical systems are revolutionizing
healthcare. A typical BAN comprises several bio-signal and motion
sensors and uses ultra-low-power short-haul radios in conjunction with
nearby smart-phones or handheld devices (with GPS capabilities) to
communicate via the internet with a doctor or other healthcare
professional. Higher energy efficiency is critical to the development
of feature-rich, wearable and reliable personal health-monitoring
systems.
The amount of data transmitted to the smart-phone increases as more
sensors are added to the BAN. Because the energy consumed for RF
transmission is proportional to the data rate, it is advantageous to
compress the bio-signal at the sensor prior to digitization and
transmission. This energy-efficient paradigm is possible using
compressed sensing?a new sampling theory wherein a compressible signal
can be acquired using only a few incoherent measurements. For ECG
signals, for example, compression factors up to 16X are achievable
which means similar reductions in energy consumption. The second part
of this talk will overview compressed sensing techniques and describe
a switched-capacitor analog front-end for bio-signal acquisition.
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