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
• CATV 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 Top 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
Clock
Data
Data
54-860 MHz
44 MHz
5-42 MHz
4
LPF