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
S12 Package
28 Pin SSOP with Heat Slug
PRODUCT DESCRIPTION
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
4
Attenuation Control
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.
ARA1400
LPF
Balun
Upstream
QPSK/16QAM
Modulator
Clock
Data
RAM
ROM
5-42 MHz
Transmit Enable/Disable
MAC
Clock
44 MHz
Data
Microcontroller
with Ethernet
MAC
Diplexer
54-860 MHz
Double-
Conversion
Tuner
SAW
Filter
QAM Receiver
with FEC
10Base-T
Transceiver
RJ45
Connector
Figure 1: Cable Modem or Set Top Box Application Diagram
03/2004
ARA1400
RF
OUT1
ATT
IN
ATT
OUT
RF
IN2
56 dB 4 dB step digital attenuator section
RF
IN
AMP
AMP
RF
OUT
ISET1
32 dB
16 dB
8 dB
4 dB
ISET2
Tx
Figure 2: Functional Block Diagram
1
2
3
4
5
6
7
8
9
10
11
12
13
14
GND
N/C
ATT
IN
RF
OUT1
V
REF1
ATT
ACG1
ATT
ACG1
ATT
ACG1
ATT
ACG1
RF
IN
I
SET1
V
ATT
32 dB
16 dB
ATT
OUT
I
SET2
RF
IN2
Tx
ATT
ACG3
ATT
ACG2
ATT
ACG2
ATT
ACG2
ATT
ACG2
RF
OUT
V
REF2
V
A2
4 dB
8 dB
28
27
26
25
24
23
22
21
20
19
18
17
16
15
Figure 3: Pinout
2
Data Sheet - Rev 2.1
03/2004
ARA1400
Table 1: Pin Description
PIN
1
2
3
4
5
6
7
8
9
10
11
12
13
14
NAME
GND
N/C
ATT
IN
RF
OUT1
V
REF1
ATT
ACG1
ATT
ACG1
ATT
ACG1
ATT
ACG1
RF
IN
I
SET1
V
ATT
32 dB
16 dB
DESCRIPTION
Ground
No Connection
(1)
PIN
15
16
17
18
19
(3)
NAME
8 dB
4 dB
V
A2
V
REF2
RF
OUT
ATT
ACG2
ATT
ACG2
ATT
ACG2
ATT
ACG2
ATT
ACG3
Tx
RF
IN2
I
SET2
ATT
OUT
DESCRIPTION
82 dB Attenution Control Bit
4 dB Attenution Control Bit
Amplifier A2 Supply
Reference Voltage for
Amplifier A2
RF Output from Switch
(2)
Attenuator AC Ground 2
Attenuator AC Ground 2
Attenuator AC Ground 2
Attenuator AC Ground 2
Attenuator AC Ground 3
Output Switch Control
Amplifier A2 Input
(4)
Amplifier A2 Current Adjust
Attenuator Output
(2)
(3)
Attenuator Input
(2)
Amplifier A1 Output and
Supply
Reference Voltage for
Amplifier A1
Attenuator AC Ground 1
Attenuator AC Ground 1
Attenuator AC Ground 1
Attenuator AC Ground 1
Amplifier A1 Input
(4)
Amplifier A1 Current Adjust
Attenuator Supply
32 dB Attenution Control Bit
16 dB Attenution Control Bit
20
21
22
23
24
25
26
27
28
(3)
(3)
(3)
(3)
(3)
(3)
(3)
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.
Data Sheet - Rev 2.1
03/2004
3
ARA1400
ELECTRICAL CHARACTERISTICS
Table 2: Absolute Minimum and Maximum Ratings
PARAMETER
Analog Supply: V
SUP
(pins 4, 12, 17)
Amplifier Reference Voltages (pins 5, 18)
RF
Power at Amplifier Inputs
(pins
10, 26
)
MIN
0
-2.5
-
0
0
-55
-
-
MAX
9
V
SUP
2
+60
6
6
+200
260
5
UNIT
VD C
VD C
dBmV
V
V
°C
°C
S ec
Attenuator Controls (pins 13, 14, 15, 16)
Output Switch Control (pin 25)
Storage Temperature
Soldering Temperature
Soldering Time
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.
Table 3: Operating Ranges
PARAMETER
Amplifier Supply: V
DD
(pins 4, 17)
Attenuator Supply: V
ATTN
(pin 12)
Attenuator Controls (pins 13, 14, 15, 16)
Amplifier Reference Voltages (pins 5, 18)
Output Switch Control (pin 25)
Case Temperature
MIN
4.5
V
DD
-0.5
0
-
0
0
TYP
5
5
-
1.75
-
25
MAX
7
7
5.5
-
5.5
85
UNIT
VDC
VD C
V
VD C
V
°C
The device may be operated safely over these conditions; however, parametric
performance is guaranteed only over the conditions defined in the electrical specifications.
4
Data Sheet - Rev 2.1
03/2004
ARA1400
Table 4: DC Electrical Specifications
(T
A
= 25 °C; V
DD
,V
ATTN
= +5.0 VDC)
PARAMETER
Amplifier A1 Current (pin 4)
Amplifier A2 Current (pin 17)
Attenuator Current (pin 12)
Total Power Consumption
MIN
-
-
-
-
TYP
74
108
12
0.97
MAX
95
130
20
1.23
UNIT
mA
mA
mA
W
COMMENTS
Table 5: AC Electrical Specifications
(T
A
= 25 °C; V
DD
, V
ATTN
= +5.0 VDC; Tx = 0 V (switch closed), Tx = +5 V (switch open))
PARAMETER
Gain (10 MHz)
Gain Flatness
Gain Variation over Temperature
Attenuation Steps
4 dB
8 dB
16 dB
32 dB
Switch Isolation at 45 MHz
Harmonics (fo = 10MHz)
2fo
3fo
3
rd
Order Output Intercept
1 dB Gain Compression Point
Noise Figure
Output Noise Power
Active / No Signal / Min. Atten. Set.
Active / No Signal / Max. Atten. Set.
Input Impedance
Note: As measured in ANADIGICS test fixture.
MIN
30
-
-
3.6
7.7
15.3
31.0
-
TYP
32
0.75
-0.006
3.9
8.0
15.7
31.5
35
MAX
33
-
-
4.2
8.3
16.1
32.0
30
UNIT
dB
dB
dB/°C
COMMENTS
0 dB attenuation setting
5 to 100 MHz
dB
Monotonic
dB
Difference in output
signal level between
active and standby
fo power = +60 dBmV
into 75 Ohms
-
-
78
-
-
-
-
-
-57
-64
-
70
1.7
-
-
75
-52
-56
-
-
2.5
-37.6
-54.6
-
dB c
dBmV
dBmV
dB
dBmV
Ohms
Any 160 kHz bandwidth
from 5 to 42 MHz
Data Sheet - Rev 2.1
03/2004
5
