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TI introduces first single-chip digital downconverter and upconverter
for 3G base stations
January 13, 2003
Texas Instruments (TI) today introduced a new four-channel wideband
digital downconverter and upconverter that is ideal for radios in
3G wireless base transceiver systems. The flexible four-channel
device is the first chip that provides both digital downconversion
and upconversion functions in a single package. Targeted mainly
towards CDMA2000 and W-CDMA base station systems, the new device
also offers superior digital radio performance for other applications
such as wireless repeaters, cable modem radios, wireless instrumentation
and defense-based digital radio systems.
TI's GC5016 enables wireless infrastructure manufacturers to take
advantage of the industry's best performance in digital down and
upconversion in a single device. It offers outstanding 3G performance
with 150 MSPS clocking, flexible wideband digital filtering, many
input-output interfacing options and very low power dissipation.
"We will be combining downconversion and upconversion blocks at
even higher levels of integration in future devices," said Brad
Evans, systems engineer for TI's wireless infrastructure radio products
group. "This will give base station manufacturers a proven low-cost
high-performance option over developing expensive in-house custom
ASIC-based radio chain solutions."
Using a single device for downconversion and upconversion for receive
and transmit functions, manufacturers can drive costs down for base
stations, macrocell, microcell and picocell base stations as well
as wireless repeaters. This also means that base station radio engineers
need to become familiar with only one device for both downconverter
and upconverter functions.
Each of the GC5016's four downconverter or upconverter channels
can be independently configured. Operating mode, tuning frequency,
channel filtering, automatic gain control and input-output options
can be programmed over a microprocessor bus. Channel filtering consists
of a six-stage CIC filter and a programmable FIR filter. The FIR
filter provides up to 255 taps for UMTS and CDMA2000 modes. Spurious-free
dynamic range is an industry-best at better than -115 dBC. Power
dissipation is about 600 milliWatts when clocking at 100 MHz with
four channels configured for UMTS operation. Together, these features
provide performance better than any other 3G digital downconverter
or upconverter device available today.
In downconversion mode, the GC5016 accepts signal data from an
analog-to- digital converter. The GC5016 tunes the desired signal
to baseband and then isolates the desired signal by applying pulse-shape
filtering. The isolated signal is then decimated and output for
subsequent chip-rate and symbol rate processing. Further signal
processing and demodulation is handled with a programmable DSP chip.
In upconversion mode, the GC5016 accepts complex digital signal
data from a baseband source. This signal data is then interpolated,
pulse-shape filtered, modulated to a programmed intermediate frequency,
and then output to an external digital-to-analog converter. The
GC5016 also supports complex outputs for direct I/Q upconversion
and power amplifier digital pre-distortion linearization processing.
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3G Motorola A920
