05/2005
ARA05050
Reverse Amplifier with Step Attenuator
Data Sheet - Rev 2.2
FEATURES
Low Cost Integrated Monolothic GaAs Amplifier
With Step Attenuator
Attenuation Range: 0-30 dB, Adjustable In
2dB Increments Via a 4 Wire Parallel Control
Meets DOCSIS Distortion Requirements at
+58dBmV Output Signal Level
Low Distortion and Low Noise
Low Signal toNoise Ratio at All Gain Levels
Frequency Range: 5-100 MHz
5 Volt Operation
RoHS-Compliant Package Option
APPLICATIONS
MCNS/DOCSIS Compliant Cable Modems
CATV Interactive Set-Top Box
OpenCable Set-Top Box
Fiber Nodes
Cable Modem Termination Systems (CMTS)
PRODUCT DESCRIPTION
The ARA05050 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. This device is capable of meeting
the MCNS/DOCSIS requirements for harmonic
Figure 1. Cable Modem or Set Top Box Application Diagram
S12 Package
28 Pin SSOP with Heat Slug
Diplexer
ARA05050
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
Switch
performance at a +58dBmV output level while
requiring only a single polarity +5V supply. Both the
input and the output are single-ended and matched
to 75 Ohms. The precision attenuator provides up to
30 dB of attenuation in 2 dB increments. The
ARA05050 is offered in a 28-pin SSOP package that
features a heat slug on the bottom of the package,
and is available in a RoHS-compliant option.
2
Data Sheet - Rev 2.2
05/2005
ARA05050
Figure 2: Functional Block Diagram
Figure 3: Pinout
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
GND
I
SET1
ATT
OUT
ATT
ACG1
RF
IN2
V
REF1
RF
OUT1
ATT
IN
16 dB
V
ATT
8 dB
RF
IN
I
SET2
RF
OUT
Bypass
2 dB
N/C
4 dB
ATT
ACG1
ATT
ACG1
ATT
ACG1
V
REF2
ATT
ACG2
ATT
ACG2
ATT
ACG2
ATT
ACG2
N/C
N/C
RF
IN
RF
OUT
I
SET2
I
SET1
16 dB
2 dB
4 dB
8 dB
RF
IN2
RF
OUT1
ATT
OUT
ATT
IN
A1
A2
30 dB, 2dB step digital attenuator section
4
Data Sheet - Rev 2.2
05/2005
ARA05050
ELECTRICAL CHARACTERISTICS
R
E
T
E
M
A
R
A
P
N
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Table 2: Absolute Minimum and Maximum Ratings
Table 3: Operating Ranges
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1
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C
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.
The device may be operated safely over these conditions; however, parametric
performance is guaranteed only over the conditions defined in the electrical specifications.
Notes:
1. Pins 3 and 26 should be AC-coupled. No external DC bias should be applied.
2. Pins 10, 11, 24 and 25 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 and 23 should be AC-grounded. No external DC bias
should be applied.
Data Sheet - Rev 2.2
05/2005
5
ARA05050
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.
1
W
Notes:
(1) See Figures 5 and 6 for performance at higher frequencies.
All specifications as measured in ANADIGICS test fixture.
Table 4: DC Electrical Specifications
T
A
=25
C; V
DD
, V
ATTN
= +5.0 VDC
Table 5: AC Electrical Specifications
T
A
=25
C; V
DD
, V
ATTN
= +5.0 VDC
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