AD6644/AD6624/AD6622/AD9772 - Analog Devices

ENABLING TECHNOLOGY FOR

NEXT-GENERATION SOFTWARE

BASE STATIONS

Analog Devices introduces the latest in Direct IF

Sampling (DIFS) and Direct Digital Synthesis

(DDS) technology to reduce the cost, size, and

power of traditional multicarrier radios.

Finally, the dynamic range barriers in converter

technology have been overcome to permit

an entire 25 MHz spectrum to be digitally

processed. Incremental RF carriers are easily

added (or reprogrammed) for most air interface

standards.

APPLICATIONS

Micro/Pico Cell Transceivers

In-building Wireless Base Stations

Wireless Local Loop

Software Programmable Base Stations

Phased Array Antenna Systems

Analog Devices’

SoftCell chipset cuts

the component

count for wireless

base stations.

AD6644/AD6624/AD6622/AD9772

RECEIVE SIGNAL PROCESSOR FEATURES

• Single Analog-to-Digital Converter (ADC) digitizes 25 MHz spectrum:

replaces multiple radios for reduced size and cost

• AD6644 14-bit 65 MSPS ADC: samples multiple channels with 100 dB

dynamic range and 75 dB SNR

• AD6624 Quad Digital Receive Signal Processor: four independent digital

receivers on a single chip, replacing expensive analog tuners and filters

• Digital tuner/filters are programmable for AMPS, IS136, GSM, EDGE,

PHS, and NMT. Noninteger decimation rates allow multiple air interfaces

within a single chipset

TRANSMIT SIGNAL PROCESSOR FEATURES

• Direct Digital Synthesis eliminates multiple analog modulators and the

matching problems they present

• AD6622 Quad Digital Transmit Signal Processor: independently

interpolates, filters, tunes, and combines four carriers per chip

• AD9772 14-bit 2X interpolating 400 MSPS TxDAC®: optimized for high

dynamic range and low distortion in a multicarrier environment

• Programmable channel filtering using linear I and Q inputs or pulse

shaping for most air interface standards

SOFTCELL

™MULTICARRIER TRANSCEIVER CHIPSET

DAC Transmit IF

DUC

Format,

Pulse Shape

DUC

Format,

Pulse Shape

DUC

Format,

Pulse Shape

DUC

Format,

Pulse Shape

TigerSHARC

DSP

Digital Filter

(Channelizer)

Digital Filter

(Channelizer)

Digital Filter

(Channelizer)

Digital Filter

(Channelizer)

ADC

Receiver IF

AD6644 AD6624 AD6622 AD9772

™

FLEXIBLE AND

PROGRAMMABLE

Analog Devices’ versatile design

enables you to manufacture

base stations for a variety of air

interface standards—using the

same core elements.

Software receivers can be

tuned to different channels and

modulation standards without

expensive hardware changes.

This all-digital approach can

also be used for fixed-access

receivers in wireless local loops.

FUTURE-PROOF

ARCHITECTURE

Once deployed, base stations

using these programmable

receivers can be readily recon-

figured by network operators to

adapt to standards as they

evolve. SoftCell allows your

customers to take some of the

guesswork out of future net-

work planning. As new micro-

cells and picocells are added to

increase network capacity,

operators can easily implement

new frequency plans through

software.

Direct IF Sampling and

Direct Digital Synthesis plat-

forms offer a flexible environ-

ment for 3G developments,

including IS95 and Wideband

CDMA air interface standards.

In transmitters, the AD6622

can be configured to support

IS95 (including transmit pre-

distortion phase equalizer) and

5 MHz WBCDMA signals. Digital

receivers for 1.25 MHz to 5 MHz

carriers will be supported in

follow-on products to the

AD6624.

INNOVATIVE DESIGN SAVES

TIME AND MONEY

Analog Devices’ all-digital

approach enables RF channels

to be consolidated within a

single ADC. The front-end

section is therefore smaller and

less expensive to manufacture.

Channel-select filtering takes

place in the digital signal

processor.

Characteristics for band-

width, passband ripple, and

stopband rejection are speci-

fied through software, rather

than by sensitive and costly-

to-produce analog filters.

By reducing front-end filter-

ing requirements, this chipset

solution cuts assembly costs

and eliminates the need for

extensive factory adjustments

of analog components.

COST-EFFECTIVE FOR MULTI-

CHANNEL SYSTEMS

With a single AD6644 ADC

digitizing an entire 25 MHz of

spectrum, this advanced wide-

band receiver can deliver a

lower cost-per-channel than

traditional receivers.

The AD6622 and AD6624

are optimized for four-channel

applications.

To increase capacity, simply

add digital transmit/receive

chips to provide additional RF

channels.

This easy add-on capability

makes Analog Devices’ SoftCell

ideal for high-volume, multi-

channel cellular systems. As

the number of channels

increases, the cost per channel

is reduced because of shared

hardware costs.

SoftCell ensures that your

customers’ hardware investment

is fully protected.

HIGH SFDR FOR OPTIMUM

SENSITIVITY

This high-performance receiver

maintains a spurious-free

dynamic range (SFDR) of

100 dB over a 25 MHz band-

width. The AD6644 enables the

receiver to maintain a signal-to-

noise ratio (SNR) of 75 dB, prior

to digital filtering. The AD6624

Digital Receive Signal Processor

provides additional processing

gain of 20 dB – 35 dB.

ANALOG DEVICES: LEADING

BASE STATION SUPPLIER

At the forefront of next-

generation receiver technology,

Analog Devices is an established

supplier of integrated circuits

used in current cellular base

station subsystem designs.

We have the largest market

share of mixed-signal integrated

circuits in base stations world-

wide. And we also hold a lead-

ership position in high-speed

conversion technology and high

dynamic range sampling.

SoftCell Transceiver Chipset

SOFTCELL MULTICARRIER

TRANSCEIVER CHIPSET

• AD6644 14-bit 65 MSPS

ADC

The AD6644 is an 65 MSPS,

high dynamic range 14-bit

ADC optimized to sample IF

inputs up to 70 MHz. CMOS-

compatible, this high-

performance ADC provides

100 dB of SFDR and 75 dB

SNR in a 25 MHz bandwidth.

• AD6624 Quad Digital

Receive Signal Processor

The AD6624 contains four

independent digital decimat-

ing receivers, each providing

over 100 dB of SFDR. Each

channel contains a digital

tuner, two stages of fixed

coefficient filters, and a user-

programmable decimating

filter.

• AD6622 Quad Digital

Transmit Signal Processor

This four-channel transmit

signal processor accepts I

and Q inputs and digitally

filters, interpolates, and

tunes the baseband signal to

the desired digital IF. Each

independent channel is com-

bined in a single 18-bit paral-

lel output that can be com-

bined with additional

AD6622s to increase the

number of carriers support-

ed. Pulse shaping and

matched filtering can be pro-

grammed to support most air

interface standards.

• AD9772 14-bit 400 MSPS

2X Interpolating TxDAC

The AD9772 accepts wide-

band digital input at rates up

to 150 MSPS, and generates

a spectrally pure IF output at

frequencies up to 60 MHz.

The resolution and ac accu-

racy of the AD9772 minimize

spurious signals, improve

dynamic range, and simplify

upconversion to the next IF

frequency.

or send e-mail to:

wireless.infrastructure@

analog.com

reserved. Trademarks and registered

trademarks are the property of their

respective companies. SoftCell is a

trademark of Analog Devices, Inc.

Printed in the U.S.A. H3518a-2-2/00 (rev. A)

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