12-Bit, 165 MSPS

TxDAC

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PRODUCT DESCRIPTION

The AD9742 is a 12-bit resolution, wideband, third generation

member of the TxDAC series of high-performance, low power

CMOS digital-to-analog converters (DACs). The TxDAC family,

consisting of pin-compatible 8-, 10-, 12-, and 14-bit DACs, is

specifically optimized for the transmit signal path of communica-

tion systems. All of the devices share the same interface options,

small outline package, and pinout, providing an upward or down-

ward component selection path based on performance, resolution,

and cost. The AD9742 offers exceptional ac and dc performance

while supporting update rates up to 165 MSPS.

The AD9742’s low power dissipation makes it well suited for

portable and low power applications. Its power dissipation can be

further reduced to a mere 60 mW with a slight degradation in

performance by lowering the full-scale current output. Also, a

power-down mode reduces the standby power dissipation to

approximately 15 mW. A segmented current source architecture

is combined with a proprietary switching technique to reduce

spurious components and enhance dynamic performance. Edge-

triggered input latches and a 1.2 V temperature compensated

band gap reference have been integrated to provide a complete

monolithic DAC solution. The digital inputs support 3 V CMOS

logic families.

PRODUCT HIGHLIGHTS

1. The AD9742 is the 12-bit member of the pin compatible

TxDAC family that offers excellent INL and DNL

performance.

2. Data input supports two’s complement or straight binary

data coding.

3. High-speed, single-ended CMOS clock input supports

165 MSPS conversion rate.

4. Low power: Complete CMOS DAC function operates on

135 mW from a 3.0 V to 3.6 V single supply. The DAC full-

scale current can be reduced for lower power operation, and

a sleep mode is provided for low power idle periods.

5. On-chip voltage reference: The AD9742 includes a 1.2 V

temperature-compensated band gap voltage reference.

6. Industry standard 28-lead SOIC and TSSOP packages.

TxDAC is a registered trademark of Analog Devices, Inc.

* Protected by U.S. Patent Numbers 5568145, 5689257, and 5703519.

12-Bit, 165 MSPS

TxDAC

FUNCTIONAL BLOCK DIAGRAM

150pF

+1.20V REF

AVDD

ACOM

REFLO

CURRENT

SOURCE

ARRAY

3.3V

SEGMENTED

SWITCHES

LSB

SWITCHES

REFIO

FS ADJ

DVDD

DCOM

CLOCK

3.3V

0.1 F

CLOCK

IOUTA

IOUTB

LATCHES

AD9742

SLEEP

DIGITAL DATA INPUTS (DB11–DB0)

MODE

FEATURES

High Performance Member of Pin-Compatible

TxDAC Product Family

Excellent Spurious-Free Dynamic Range Performance

SNR @ 5 MHz Output, 125 MSPS: 73 dB

Two’s Complement or Straight Binary Data Format

Differential Current Outputs: 2 mA to 20 mA

Power Dissipation: 135 mW @ 3.3 V

Power-Down Mode: 15 mW @ 3.3 V

On-Chip 1.20 V Reference

CMOS-Compatible Digital Interface

Package: 28-Lead SOIC and TSSOP Packages

Edge-Triggered Latches

APPLICATIONS

Wideband Communication Transmit Channel:

Direct IF

Base Stations

Wireless Local Loop

Digital Radio Link

Direct Digital Synthesis (DDS)

Instrumentation