A ARA05050S12CATV Reverse Amplifier w/ Step AttenuatorAdvanced product informationRev. 6
DESCRIPTION
The ARA05050 is a GaAs IC designed to perform 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. It is capable of meeting the MCNS/DOCSIS
harmonic distortion specifications while only requiring a
single polarity +5V supply. This part is a single ended
design that does not require an output balun to achieve
-55 dBc 2nd harmonic performance at +58 dBmV output
FEATURES
• Integrated monolithic GaAs amplifier and step
attenuator.
• Compatible with all digital and analog modulation types.
• Frequency range: 5 - 100 MHz.
• Gain: 0 - 30 dB, variable in 2 dB steps.
• 5 Volt operation.
• Low noise figure.
• Low distortion.
• Amplifier shutdown capability.
• Low cost.
• High reliability.
• Low signal to noise ratio at all gain levels. S12C28 Pin SSOP w/ Heat Slug
Figure 1. Cable Modem or Interactive Set-Top Box Block Diagram
*See ANADIGICS ACU50751 and ACD0900
PA PAATTN2/4/8/16 dB LPF
Upstream
QPSK/
16-QAM
Modulator
MAC
QAM
Receiver
w/FEC
SAW
Double
Conversion
Tuner
Microcontroller
w/Enet MAC
RAM
ROM
10Base-T
Tranceiver
Diplex
Filter
ARA05050 Reverse AmpSwitch
5-42 MHz
54-860 MHz
Gain Control
Clock
Clock
Data
Data
RJ45
Connector
Coax
Connector
Balun
45 MHz IF
Tx Enable/Disable
levels. Both the input and output are
matched to 75 ohms. The precision
attenuator provides up to 30 dB of
attenuation in 2 dB increments. The
ARA05050 is supplied in a 28-pin SSOP
package featuring a thermal heat slug on
the bottom of the package. Soldering this
heat slug to the ground plane of the PC
board ensures the lowest possible thermal
resistance for the device resulting in a
long MTF.