Distributed Amplifiers with Built-In Filtering for UWB Impulse Radio

Brief Description:
This technology provides a distributed amplifier (DA) with built-in, on-chip filters so that the frequency response of the distributed amplifier is controlled, on chip, not only within the pass band, but also in the transition and stop bands.    The very precise filtering is particularly useful for UWB impulse radios, which need to control interference between UWB and existing narrow-band wireless communication.

Distributed amplifiers are widely used in wideband systems, such as ultra wideband (UWB) radio, radar, ultra-fast instrumentation, high speed fiber optics communications and future wide band wireless systems for the home and office.   The front end amplifiers for these applications require multi-gigahertz bandwidth and good out-of-band spectrum control to reject interference and reduce noise.
UWB is a very low power wireless technology in which data is transmitted in short duration (nanosecond) pulses rather than a sine-wave RF carrier, as in existing wireless.  It can support high speed high content data transfer over short ranges, and would be applied in wireless personal area networks (WPAN) for computing, industrial automation and home entertainment appliances.  

This design provides better control of both pass-band and stop-band characteristics of distributed amplifiers by the use of non-uniform filtering structures instead of conventional constant-k sections. Interference from out-of-band emissions is a problem that this invention corrects.
Because of the better stop-band filtering, this distributed amplifier concept makes it possible to use a larger fraction of the allowable UWB spectrum of 7 GHz.  Current UWB solutions use about 500 MHz of bandwidth, because of the need to avoid interference problems.   Since the maximum data rate is ultimately dependent on the bandwidth of the communication channel, if the channel is increased to near the maximum, the data rate could be increased by as much as a factor of 10.  Or alternatively, with the use of the full bandwidth, lower power would be required in transmission.  So in such a spread-spectrum application, power usage could be reduced significantly, for a given data rate, compared to the current systems at a 500 MHz bandwidth.
The on-chip filters may be dynamically re-configured.  This would provide an additional benefit for use in particular applications and geographies to address various potential interference bands in the radio spectrum. 
A key benefit of on-chip filtering is to lower the cost of the UWB system.  Today the UWB chips can cost as low as $2, but require off-chip filters, which can cost $0.10 to $1.   With this design, providing on-chip filtering, the chip cost will most likely not increase at all.   The cost saving of from 5 to 35% is significant in this market.

URV Reference Number: 2-11144-06008
Patent Information:
Title Country Patent No. Issued Date
Distributed Amplifiers with Built-In Filtering Functions United States 7,498,883 3/3/2009
Computer Hardware
For Information, Contact:
Curtis Broadbent
Licensing Manager
University of Rochester
Hui Wu
Yunliang Zhu