Multichannel Digital Upconverter with
VersaCREST鈩?Crest Reduction Engine
AD6633
FEATURES
4 or 6 wideband digital upconverter channels
VersaCREST crest reduction engine reduces demands on
external power amplifiers
One 20-bit complex input port (I, Q interleaved), shared
among 4 or 6 processing channels
Two 18-bit output ports for parallel I and Q or a single 18-bit
output port for interleaved I and Q
All-pass phase equalizer filters (meets IS-95 requirements)
Programmable RAM coefficient FIR filters (RCF) with
resampling
FIR interpolating filters, 2 per channel
Fifth-order interpolating CIC filter, 1 per channel
Full complex NCO, 32-bit tuning resolution (fine), worst spur
better than 鈭?05 dBc, 1 per channel
Complex FIR filter for frequency equalization or additional
filtering
Output automatic gain control
Full complex composite NCO, 6-bit tuning resolution
16-bit/8-bit MicroPort (Intel廬 or Motorola廬 mode)
Serial control port (SPI廬- or SPORT-compatible)
3.3 V I/O and 1.8 V core supplies
JTAG boundary scan
User-configurable, built-in, self-test (BIST) capability
GENERAL DESCRIPTION
The AD6633 is a multichannel, wide bandwidth digital
upconverter (DUC) with crest factor reduction (CFR) technology,
which is available in 4-channel or 6-channel versions. It processes
20-bit baseband input data and generates 18-bit, wideband, real,
or complex output data at up to 125 MSPS. This rate is suitable
for driving digital-to-analog converters (DACs) at the first
intermediate frequency (IF) directly.
The AD6633 synthesizes multicarrier and multistandard digital
signals to drive the DAC(s) with up to six wideband modulated
carriers from a single output port. Each channel includes an
internal peak-to-average power reduction block that reduces
power amplifier (PA) power dissipation. The user-configurable
interpolating filter (RCF) provides multirate processing
(including resampling) and malleable FIR filter characteristics.
An all-pass phase equalizer designed to comply with the
cdma2000 standard follows the RCF. Each channel has its own
32-bit numerically-controlled oscillator (NCO) to up-convert
the filtered/interpolated data to the first IF. Interpolation, anti-
image filtering, all-pass equalization, and NCO tuning functions
are combined in a single, cost-effective device.
Digital IF signal processing provides repeatable manufacturing,
higher accuracy, and more flexibility than comparable high
dynamic range analog designs. The AD6633 uses a 3.3 V I/O
power supply and a 1.8 V core power supply. Typical power
consumption is 75 mW per channel or 1.4 W for the complete
device. All I/O pins are 5 V tolerant. All control registers and
coefficient values are programmed through a generic 16-bit
microprocessor interface or a SPI/SPORT-compatible serial
port. Intel and Motorola microprocessor bus modes are
supported. All inputs and outputs are LVCMOS-compatible.
For more information about the AD6633, contact Analog Devices
via email at
versaCOMM@analog.com.
GAIN[2:0]
INPUT
CLOCK
APPLICATIONS
Cellular/PCS basestations
Micro/pico cell basestations
Multicarrier cdma2000廬, WCDMA, TD-SCDMA basestations
Broadband wireless access head ends (LMDS, MMDS)
Software defined radios
High speed signal processing applications
HALF-BAND FILTER
SUM MONITOR
QUADRATURE
CORRECTION
MULTIPLEXED
I AND Q DATA[19:0]
I/Q
CH[2:0]
INPUT ACK
INPUT REQ
MUX
AND
FIFO
VersaCREST
WIDEBAND CHANNEL
COMPLEX FIR
COARSE NCO
SUMMATION
Figure 1. Functional Block Diagram
Rev. Sp0
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.326.8703
漏 2004 Analog Devices, Inc. All rights reserved.
04939-001
VersaCREST
I[17:0]
AGC
Q[17:0]
1
2
