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© Analog Devices, Inc., 2002

AD6645

14-Bit, 80 MSPS

A/D Converter

REV. 0

FEATURES

80 MSPS Guaranteed Sample Rate

100 dB Multitone SFDR

IF Sampling to 200 MHz

Sampling Jitter 0.1 ps

1.5 W Power Dissipation

Differential Analog Inputs

Pin-Compatible to AD6644

Two’s Complement Digital Output Format

3.3 V CMOS-Compatible

DataReady for Output Latching

APPLICATIONS

Multichannel, Multimode Receivers

Base Station Infrastructure

AMPS, IS-136, CDMA, GSM, WCDMA

Single Channel Digital Receivers

Antenna Array Processing

Communications Instrumentation

Radar, Infrared Imaging

Instrumentation

PRODUCT DESCRIPTION

The AD6645 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

the chip to provide a complete conversion solution. The AD6645

provides CMOS-compatible digital outputs. It is the fourth

generation in a wideband ADC family, preceded by the

AD9042 (12-bit, 41 MSPS), the AD6640 (12-bit, 65 MSPS,

IF sampling), and the AD6644 (14-bit, 40 MSPS/65 MSPS).

Designed for multichannel, multimode receivers, the AD6645 is

part of Analog Device’s SoftCell™ transceiver chipset. The

AD6645 maintains 100 dB multitone, spurious-free dynamic

range (SFDR) through the second Nyquist band. This break-

through performance eases the burden placed on multimode

digital receivers (software radios) that are typically limited by

the ADC. Noise performance is exceptional; typical signal-to-

noise ratio is 74.5 dB through the first Nyquist band.

The AD6645 is built on Analog Devices’ high-speed complemen-

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

circuit architecture. Units are available in a thermally enhanced 52-

lead PowerQuad 4

∞C to +85∞C.

PRODUCT HIGHLIGHTS

1. IF Sampling

The AD6645 maintains outstanding ac performance up to

input frequencies of 200 MHz. Suitable for multicarrier 3G

wideband cellular IF sampling receivers.

2. Pin Compatibility

The ADC has the same footprint and pin layout as the

AD6644, 14-Bit 40 MSPS/65 MSPS ADC.

3. SFDR Performance and Oversampling

Multitone SFDR performance of –100 dBc can reduce the

requirements of high-end RF components and allows the use

of receive signal processors such as the AD6620 or AD6624/

AD6624A.

FUNCTIONAL BLOCK DIAGRAM

5

A1

TH2

A2

TH4

ADC3

TH5

TH3

TH1

DAC1

ADC2

DAC2

ADC1

6

AIN

AIN

VREF

ENCODE

ENCODE

GND

DMID

OVR

DRY

D13

MSB

D12

D11

D10

D9D8D7D6D5D4D3D2

D1D0

LSB

INTERNAL

TIMING

5

DIGITAL ERROR CORRECTION LOGIC

AD6645

2.4V

SoftCell is a trademark of Analog Devices, Inc.

PowerQuad 4 is a registered trademark of Amkor Technology, Inc.