AD8322ARU-REEL Analog Devices Inc, AD8322ARU-REEL Datasheet - Page 9

• Manufacturer Part Number: AD8322ARU-REEL
• Description: IC LN DVR CATV COARS-STP 28TSSOP
• Manufacturer: Analog Devices Inc
• Type: Line Driver, Transmitterr

Specifications of AD8322ARU-REEL

• Rohs Status: RoHS non-compliant
• Applications: Modems, Set-Top Boxes
• Mounting Type: Surface Mount
• Package / Case: 28-TSSOP
• For Use With: AD8322-EVAL - BOARD EVAL FOR AD8322

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in an adjacent channel which could be occupied by a carrier of
the same or different symbol rates.” Figure 7 shows the measured
ACP, for a 16 QAM, 60 dBmV signal, taken at the output of the
AD8322 evaluation board (see Figure 13 for evaluation board
schematic). The transmit channel width and adjacent channel
width in Figure 7 correspond to symbol rates of 160 K
Table II shows the ACP results for the AD8322 for all conditions
in DOCSIS Table 4-7 “Adjacent Channel Spurious Emissions.”
Noise and DOCSIS
At minimum gain, the AD8322’s output noise spectral density is
12 nV/√Hz measured at 10 MHz. DOCSIS Table 4-8, “Spurious
Emissions in 5 MHz to 42 MHz” specifies the output noise for
various symbol rates. The calculated noise power in dBmV for
160 K
Comparing the computed noise power of –46.4 dBmV to the
8 dBmV signal yields –54.4 dBc, which meets the required level
of –53 dBc set forth in DOCSIS Table 4-8. As the AD8322’s
gain is increased from this minimum value, the output signal
increases at a faster rate than the noise, resulting in a signal-to-
noise ratio that improves with gain. In transmit disable mode
the output noise spectral density computed over 160 K
1.0 nV/√Hz or –68 dBmV.
SYMBOL RATE
1280 K
160 K
320 K
640 K
2560 K
TRANSMIT
CHANNEL


 

SYM/SEC
SYM/SEC
SYM/SEC
20
SYM/SEC
SYM/SEC
SYM/SEC
–10
–20
–30
–40
–50
–60
–70
–80
log
CENTER 10MHz
CL1
RBW 500Hz RF ATT 40dB
VBW 5kHz
SWT 12s UNIT dBm




160 K
is:



–54.2
–53.8
–54.0
–53.9
–54.2
12
SYM/SEC
Hz
nV
CL1
ADJACENT CHANNEL SYMBOL RATE

 ×

320 K
2
–54.7
–54.6
–54.1
–54.1
–54.2
C0
SYM/SEC
160
60kHz
kHz
640 K
–55.4
–54.6
–54.5
–53.9
–54.2




SYM/SEC


 

C0
+
CH PWR 5.39dBm
ACP UP –54.22dB
ACP LOW –56.84dB
60
CU1
1280 K
=
SPAN 600kHz
–56.6
–55.1
–54.4
–54.3
–53.8
–
SYM/SEC
46 4
.
CU1
F1
dBmV
2560 K
SYM/SEC
SYM/SEC
–55.9
–54.8
–54.1
–53.7
–53.5
SYM/SEC
.
is
Evaluation Board Features and Operation
The AD8322 evaluation board (Part # AD8322-EVAL) and
control software can be used to control the AD8322 upstream
cable driver via the parallel port of a PC. A standard printer cable
connected between the parallel port and the evaluation board is
used to feed all the necessary data to the AD8322 by means of the
Windows
package provides a means of evaluating the amplifier by provid-
ing a convenient way to program the gain/attenuation as well
as offering easy control of the amplifiers asynchronous PD pin.
With this evaluation kit the AD8322 can be evaluated with either
a single-ended or differential input configuration. The amplifier
can also be evaluated with or without the PULSE diplexer in the
output signal path. To remove the diplexer from the signal path,
move the two 0 Ω chip resistors R18 and R10 to locations R11 and
R20. A schematic of the evaluation board is provided in Figure 13.
Overshoot on PC Printer Ports
The data lines on some PC parallel printer ports have excessive
overshoot that may cause communications problems when pre-
sented to the CLK pin of the AD8322 (TP5 on the evaluation
board). The evaluation board was designed to accommodate
a series resistor and shunt capacitor (R1 and C15) to filter the
CLK signal if required.
Transformer and Diplexer
A 1:1 transformer is needed to couple the differential outputs of
the AD8322 to the cable while maintaining a proper impedance
match. The specified transformer is available from TOKO (Part
# 617DB-A0070), however, MA/COM part # ETC-1-1T-15
can also be used. The evaluation board is equipped with the
TOKO transformer, but is also designed to accept the MA/COM
transformer. The PULSE diplexer included on the evaluation
board provides a high-order low-pass filter function, typically
used in the upstream path. The ability of the PULSE diplexer to
achieve DOCSIS compliance is neither expressed nor implied by
Analog Devices Inc. Data on the diplexer should be obtained
from PULSE.
Differential Inputs
The AD8322-EVAL evaluation board is designed to accommo-
date a Mini-Circuits T1-6T-KK81 1:1 transformer for the purpose
of converting a single-ended (ground referenced) input signal to
differential inputs. Figure 8 and the following paragraphs iden-
tify three options for providing differential input signals to the
AD8322 evaluation board.
®
based, Microsoft Visual Basic control software. This
AD8322