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a

AD6644

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781/329-4700

World Wide Web Site: http://www.analog.com

Fax: 781/326-8703

© Analog Devices, Inc., 2000

14-Bit, 40 MSPS/65 MSPS

A/D Converter

FUNCTIONAL BLOCK DIAGRAM

5

ADC2

DAC2

TH4

TH3

TH5

ADC3

6

A2

5

ADC1

DAC1

TH2

TH1

A1

DIGITAL ERROR CORRECTION LOGIC

2.4V

INTERNAL

TIMING

AIN

AIN

ENCODE

ENCODE

GND

D8

D9

D10

D11

D12

D13

DRY

OVR

DMID

D0

D1

D2

D3

D4

D5

D6

D7

MSB

LSB

AD6644

FEATURES

65 MSPS Guaranteed Sample Rate

40 MSPS Version Available

Sampling Jitter < 300 fs

100 dB Multitone SFDR

1.3 W Power Dissipation

Differential Analog Inputs

Digital Outputs

Two’s Complement Format

3.3 V CMOS-Compatible

Data Ready for Output Latching

APPLICATIONS

Multichannel, Multimode Receivers

AMPS, IS-136, CDMA, GSM, Third Generation

Single Channel Digital Receivers

Antenna Array Processing

Communications Instrumentation

Radar, Infrared Imaging

Instrumentation

PRODUCT DESCRIPTION

The AD6644 is a high-speed, high-performance, monolithic

14-bit analog-to-digital converter. All necessary functions,

including track-and-hold (T/H) and reference, are included on-

chip to provide a complete conversion solution. The AD6644

provides CMOS-compatible digital outputs. It is the third genera-

tion in a wideband ADC family, preceded by the AD9042 (12-bit

41 MSPS) and the AD6640 (12-bit 65 MSPS, IF sampling.)

Designed for multichannel, multimode receivers, the AD6644 is

part of ADI’s new SoftCell™ transceiver chipset. The AD6644

achieves 100 dB multitone, spurious-free dynamic range (SFDR)

through the Nyquist band. This breakthrough performance eases

the burden placed on multimode digital receivers (software radios)

which are typically limited by the ADC. Noise performance is

exceptional; typical signal-to-noise ratio is 74 dB.

The AD6644 is also useful in single channel digital receivers

designed for use in wide-channel bandwidth systems (CDMA,

W-CDMA). With oversampling, harmonics can be placed out-

side the analysis bandwidth. Oversampling also facilitates the use of

decimation receivers (such as the AD6620), allowing the noise

floor in the analysis bandwidth to be reduced. By replacing tradi-

tional analog filters with predictable digital components, modern

receivers can be built using fewer “RF” components, resulting

in decreased manufacturing costs, higher manufacturing yields,

and improved reliability.

The AD6644 is built on Analog Devices’ high-speed complemen-

tary bipolar process (XFCB) and uses an innovative, multipass

circuit architecture. Units are packaged in a 52-terminal Low-

Profile Quad Plastic Flatpack (LQFP) specified from –25

°C

to +85

°C.

PRODUCT HIGHLIGHTS

1. Guaranteed sample rate is 65 MSPS.

2. Fully differential analog input stage.

3. Digital outputs may be run on 3.3 V supply for easy interface

to digital ASICs.

4. Complete Solution: reference and track-and-hold.

5. Packaged in small, surface-mount, plastic, 52-terminal LQFP.

SoftCell is a trademark of Analog Devices, Inc.