Wave Issue 0301 1/17/03 Article 4-04

***TI Introduces Single-Chip Digital Downconverter And
Upconverter
(January 13)

Texas Instruments Inc. (TI) today introduced a new single-chip
four-channel wideband digital downconverter and upconverter, the
GC5016. The four-channel device provides both digital
downconversion and upconversion functions in a single package,
and TI feels it is ideal for radios in 3G wireless base
transceiver systems. Targeted mainly towards CDMA2000 and W-CDMA
base station systems, the new device also offers digital radio
performance for other applications such as wireless repeaters,
cable modem radios, wireless instrumentation and defense-based
digital radio systems.

The GC5016 can provide either four channels of digital
downconversion, four channels of digital upconversion, or two
channels of downconversion and two channels of upconversion
simultaneously. Using a single device for downconversion and
upconversion for receive and transmit functions, TI stated,
manufacturers can drive costs down for base stations, macrocell,
microcell and picocell base stations as well as wireless
repeaters. However base station radio engineers will 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
better than -115 dBC. Power dissipation is about 600 milliWatts
when clocking at 100 MHz with four channels configured for UMTS
operation.

Applications requiring wider bandwidth such as cable modem head
end systems, wireless instrumentation and defense/aerospace radio
systems can benefit from the GC5016's special double-rate input
and output mode enabling effective sample rates to 300 MSPS, TI
stated.

In downconversion mode, the GC5016 accepts signal data from an
analog-to-digital converter such as TI's 12-bit 80 MSPS ADS5410.
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 such as TI's
TMS320C6416 DSP.

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 such as TI's 14-bit 125 MSPS DAC2904. The
GC5016 also supports complex outputs for direct I/Q upconversion
and power amplifier digital pre-distortion linearization
processing.

Limited preliminary samples of the GC5016 wideband digital
downconverter and upconverter are available today from TI at a
price of $65 per 1,000 units. Production devices will be widely
available in the third quarter of 2003.

www.ti.com