ARA1400S12C - Anadigics, Inc.

03/2004

PRODUCT DESCRIPTION

ARA1400

Reverse Amplifier with Step Attenuator

Data Sheet - Rev 2.1

FEATURES

• Low cost integrated monolothic GaAs amplifier

with step attenuator

• Attenuation Range: 0-56 dB, adjustable in

4 dB increments via a 4 wire parallel control

• Meets DOCSIS distortion requirements at

+60 dBmV output signal level

• Low distortion and low noise

• Frequency range: 5-100 MHz

• 5 Volt operation

• 0 to +85 °C temperature range

APPLICATIONS

• MCNS/DOCSIS Compliant Cable Modems

• CA TV Interactive Set-Top Box

• Telephony over Cable Systems

• OpenCable Set-Top Box

• Residential Gateway

The ARA1400 is a GaAs IC designed to provide the

reverse path amplification and output level control

functions in a CATV Set-Top Box or Cable Modem. It

incorporates a digitally controlled precision step

attenuator that is preceded by an ultra low noise

amplifier stage, and followed by an ultra-linear

output driver amplifier. The device is capable of

meeting the MCNS/DOCSIS requirements for

harmonic performance at a +60dBmV output level

while requiring only a single polarity +5V supply.

Both the input and the output are single-ended and

matched to 75 Ohms, and a precision attenuator

provides up to 56 dB of attenuation in 4 dB

increments. The device is offered in a 28-pin SSOP

package featuring a heat slug on the bottom of the

package.

Figure 1: Cable Modem or Set T op Box Application Diagram

S12 Package

28 Pin SSOP with Heat Slug

Diplexer

ARA1400

SAW

Filter

Double-

Conversion

Tuner

MAC

Upstream

QPSK/16QAM

Modulator

QAM Receiver

with FEC

Balun

Transmit Enable/Disable

Attenuation Control

Microcontroller

with Ethernet

MAC

RAM ROM

10Base-T

Transceiver

RJ45

Connector

Clock

Data

54-860 MHz

44 MHz

5-42 MHz

LPF

2Data Sheet - Rev 2.1

03/2004

ARA1400

Figure 2: Functional Block Diagram

Figure 3: Pinout

RFOUT1 RFIN2

ISET1 32 dB 16 dB 8 dB 4dB ISET2

RFIN

ATT IN ATT OUT

AMP RFOUT

AMP

56 dB 4 dB step digital attenuator section

GND

SET1

ATT

OUT

ATT

ACG1

IN2

REF1

OUT1

ATT

32 dB

ATT

16 dB

SET2

OUT

4dB

N/C

8dB

ATT

ACG1

ATT

ACG1

ATT

ACG1

REF2

ATT

ACG2

ATT

ACG2

ATT

ACG2

ATT

ACG2

ATT

ACG3

Data Sheet - Rev 2.1

03/2004

ARA1400

T able 1: Pin Description

Notes:

(1) All N/C pins should be grounded.

(2) Pins should be AC-coupled. No external DC bias should be applied.

(3) Pins should be AC-grounded. No external DC bias should be applied.

(4) Pins should be AC-coupled from the RF path, and should be pulled to ground through a resistor.

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4Data Sheet - Rev 2.1

03/2004

ARA1400

ELECTRICAL CHARACTERISTICS

T able 2: Absolute Minimum and Maximum Ratings

Stresses in excess of the absolute ratings may cause permanent damage.

Functional operation is not implied under these conditions. Exposure to absolute

ratings for extended periods of time may adversely affect reliability.

Notes:

1. Pins 3, 19, and 28 should be AC-coupled. No external DC bias should be applied.

2. Pins 11 and 27 should be grounded or pulled to ground through a resistor. No external

DC bias should be applied.

3. Pins 6, 7, 8, 9, 20, 21, 22, 23 and 24 should be AC-grounded. No external DC bias

should be applied.

4. Pins 10 and 26 should be AC-coupled from the RF path, and should be pulled to

ground through a resistor.

T able 3: Operating Ranges

The device may be operated safely over these conditions; however, parametric

performance is guaranteed only over the conditions defined in the electrical specifications.

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Data Sheet - Rev 2.1

03/2004

ARA1400

Note: As measured in ANADIGICS test fixture.

T able 4: DC Electrical Specifications

(TA = 25 °C; VDD,VATTN = +5.0 VDC)

T able 5: AC Electrical Specifications

(TA = 25 °C; VDD, VATTN = +5.0 VDC; Tx = 0 V (switch closed), Tx = +5 V (switch open))

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6Data Sheet - Rev 2.1

03/2004

ARA1400

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Note: As measured in ANADIGICS test fixture.

continued: AC Electrical Specifications

(TA = 25 °C; V DD, VATTN = +5.0 VDC; Tx = 0 V (switch closed), Tx = +5 V (switch open))

T able 6: Logic Interface Specifications

(TA = 25 °C; VDD, VATTN = +5.0 VDC)

Notes: “L” = logic low, “H” = logic high

T able 7: Attenuator Logic

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Data Sheet - Rev 2.1

03/2004

ARA1400

Figure 4: T est Circuit

0.1uF

227

GND

ISET1

ATTACG1

RFOUT1

ATTIN

VATT

32 dB

16 dB 8 dB

ISET2

VA2

RFIN2

4 dB

RFIN

N/C

ATTOUT

VREF1

RFOUT

ATTACG1

VREF2

ATTACG3

ATTACG2

(75 Ohms) 0.1uF

RF Output

(75 Ohms)

3.9 Ohms

16 dB

32 dB

+5 V

RF Input

+5 V

620 Ohms

0.1uF

1uF

0.1uF

ARA1400

10uH

1uF

Note:

Output Switch Closed: Output Switch Control = 0 V

Output Switch Open: Output Switch Control = +5 V

620 Ohms

4 dB

8 dB

20 Ohms

1uF

0.1uF0.1uF

1pF

3.3K Ohms

1.8K Ohms

1uF

5K Ohms

0.1uF

1uF

5K Ohms

0.1uF

Output

Switch

Control

(0 / +5 V)

5K Ohms

10K Ohms

+5 V 1uF

0.1uF

10uH

20 Ohms

3.3K Ohms

1.8K Ohms

1uF

8Data Sheet - Rev 2.1

03/2004

ARA1400

0.025 BSC 0.089 0.014 TYP

0.025 MIN.

0.099

0.197

0.163

BODY OUTLINE

(NOMINAL)

0.070 0.150

0.060 TYP.

0.400

(12X)0.020 TO 0.060 DIA.P

PLATED THRU HOLES.

DIMENSIONS IN INCHES

APPLICA TION INFORMA TION

Amplifier Enable / Disable

The ARA1400 includes two amplification stages that

each can be shut down through external control pins

VREF1 and VREF2 (pins 5 and 18, respectively). By

applying a typical bias of 1.75 Volts to these pins,

the amplifiers are enabled. In order to fully disable

an amplifier, its control pin requires a negative bias

of -1.5 to -2.0 Volts.

Output Switch Control

A switch located at the output of Amplifier A2 in the

ARA1400 provides isolation without having to

disable the amplifiers. The switch is controled by

the Tx logic input (pin 25).

Amplifier Bias Current

The ISET pins (11 and 27) set the bias current for the

amplification stages. Grounding these pins results

in the maximum possible current. By placing a

resistor from the pin to ground, the current can be

reduced. The recommended bias conditions use

the configuration shown in the test circuit schematic

in Figure 4.

Thermal Layout Considerations

The device package for the ARA1400 features a heat

slug on the bottom of the package body. Use of the

heat slug is an integral part of the device design.

Soldering it to the ground plane of the PC board will

ensure the lowest possible thermal resistance for

the device, and will result in the longest MTF (mean

time to failure.)

A PC board layout that optimizes the benefits of the

heat slug is shown in Figure 5. The via holes located

under the body of the device must be plated through

to a ground plane layer of metal, in order to provide

sufficient thermal conductivity. The recommended

solder mask outline is shown in Figure 6.

ESD Sensitivity

Electrostatic discharges can cause permanent

damage to these devices. Electrostatic charges

accumulate on test equipment and the human body,

and can discharge without detection. Proper

precautions and handling are strongly

recommended. Refer to the ANADIGICS application

note on ESD precautions.

Figure 5: PC Board Layout

Data Sheet - Rev 2.1

03/2004

ARA1400

Figure 6: Solder Mask Outline

DIMENSIONS IN INCHES

0.145

0.085

0.025 TYP.

0.016 TYP.

0.025 BSC

0.0535

0.242

0.163

0.098

0.091

10 Data Sheet - Rev 2.1

03/2004

ARA1400

P ACKAGE OUTLINE

Figure 7: S12 Package Outline - 28 Pin SSOP with Heat Slug

Data Sheet - Rev 2.1

03/2004

ARA1400

COMPONENT P ACKAGING

Figure 9: T ape Dimensions

Volume quantities of the ARA1400 are supplied on

tape and reel. Each reel holds 3,500 pieces. Smaller

quantities are available in plastic tubes of 50 pieces.

Figure 8: Reel Dimensions

WARNING

ANADIGICS products are not intended for use in life support appliances, devices or systems. Use of an ANADIGICS

product in any such application without written consent is prohibited.

IMPORTANT NOTICE

ANADIGICS, Inc.

141 Mount Bethel Road

Warren, New Jersey 07059, U.S.A.

Tel: +1 (908) 668-5000

Fax: +1 (908) 668-5132

URL: http://www.anadigics.com

E-mail: Mktg@anadigics.com

ANADIGICS, Inc. reserves the right to make changes to its products or to discontinue any product at any time without

notice. The product specifications contained in Advanced Product Information sheets and Preliminary Data Sheets are

subject to change prior to a product’s formal introduction. Information in Data Sheets have been carefully checked and are

assumed to be reliable; however, ANADIGICS assumes no responsibilities for inaccuracies. ANADIGICS strongly urges

customers to verify that the information they are using is current before placing orders.

Data Sheet - Rev 2.1

03/2004

ARA1400

ORDERING INFORMA TION

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