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
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
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