 |
The objective of this project is to generate enabling technology to reduce
the power consumption of highly integrated, low-cost, communication systems.
The cellular telephones that we routinely use today are technological marvels,
and even more amazing features for these devices are on the horizon. These new
features will include full screen real-time video, web browsing, and a variety
of downloadable applications. However, these new features will require much more
power from the battery than existing cellular phones, and the resulting battery
life will be unacceptable in most cases. Although cellular phones are capable of
greater features all the time, the batteries that power the phones do not
improve nearly as rapidly. This represents a long term problem for the cellular
telephone industry.
The purpose of this project is to significantly reduce the battery drain, and
increase the battery life, of next generation cellular telephones by developing
innovative low-cost and low-power integrated circuits that translate the
“analog” data of the world (our voices and images, and the signals that carries
that information through the air) into the “digital” data of computers. These
“analog” circuits have become significant bottlenecks in recent years, since
their performance does not improve as rapidly as that of the digital circuits
that are famously improved by “Moore’s Law.” In particular, we plan to develop
vastly improved circuits that translate analog signals into digital forms,
circuits that cancel out interfering signals so that the desired signals can be
easily heard, and low-power signal generators that precisely generate the
frequencies required by wireless communication protocols.
The research proposed in this document consists of two parts: 1) Low-Power
Wideband Fractional-N PLLs, 2) Monolithic Receiver Circuit Techniques for RF
Transmitter Leakage Interference Suppression. The two parts are separate, but
are related in that they each will develop techniques intended to reduce power
consumption in critical high-performance circuit blocks for wireless
communication systems.
The research in Part 1 will extend the work performed under a previous CoRe
project. Major results of the previous project are a new phase noise
cancellation technique that extends the bandwidth of a fractional-N PLL without
increasing phase noise, and a prototype IC that demonstrates the technique in a
state-of-the-art Bluetooth wireless LAN compliant synthesizer. The proposed
project will develop several enhancements of the original technique to reduce
power consumption without degrading performance. A second-generation prototype
IC will be developed to demonstrate the proposed techniques.
The research in Part 2 will investigate novel receiver interference suppression
techniques for 3rd generation cellular handset receivers. We propose to
investigate a novel active filter implementation of the SAW transmitter
rejection filter that has low Noise Figure and distortion, as well as low power
dissipation, which can replace the external SAW filter in most critical
applications. Of course, an active filter will never have performance equal to
that of a SAW filter, but significant improvements in active filter design will
enable the elimination of the SAW filter in many applications. Active filters
have well-known limitations for radio frequency and microwave applications –
primarily related to poor Noise Figure and dynamic range. We have developed some
active circuit techniques that will overcome these fundamental dynamic range
limitations. The second problem arising from the use of monolithic filters is
the accuracy of the frequency response. For example, in a 3G UMTS transmitter,
the interfering frequency will have a 5 MHz bandwidth, at a center frequency of
approximately 1950 MHz (approximately 0.25% fractional bandwidth!). This level
of accuracy is very difficult to achieve in a monolithic circuit, and we have
developed some novel approaches to achieve a high degree of accuracy.
The following CWC faculty are participating in this research project: Ian Galton(lead PI),
and Larry Larson.
|
|
|
 |
|
Affiliated Faculty
CoRe Research Projects