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参数资料
| 型号： | AD8325ARU-REEL |
| 厂商： | ANALOG DEVICES INC |
| 元件分类： | 模拟信号调理 |
| 英文描述： | 5 V CATV Line Driver Fine Step Output Power Control |
| 中文描述： | SPECIALTY ANALOG CIRCUIT, PDSO28 |
| 封装： | TSSOP-28 |
| 文件页数： | 9/16页 |
| 文件大小： | 304K |
| 代理商： | AD8325ARU-REEL |
REV. 0
AD8325
–9–
Distortion, Adjacent Channel Power, and DOCSIS
In order to deliver 58 dBmV of high fidelity output power required
by DOCSIS, the PA should be able to deliver about 61 dBmV
in order to make up for losses associated with the transformer
and diplexer. TPC 7 and TPC 8 show the AD8325 second and
third harmonic distortion performance versus fundamental
frequency for various output power levels. These figures are
useful for determining the inband harmonic levels from 5 MHz
to 65 MHz. Harmonics higher in frequency will be sharply attenu-
ated by the low-pass filter function of the diplexer. Another
measure of signal integrity is adjacent channel power or ACP.
DOCSIS section 4.2.9.1.1 states,
“
Spurious emissions from
a transmitted carrier may occur in an adjacent channel that could
be occupied by a carrier of the same or different symbol rates.
”
TPC 12 shows the measured ACP for a 16 QAM, 61dBmV signal,
taken at the output of the AD8325 evaluation board (see Figure
12 for evaluation board schematic). The transmit channel width
and adjacent channel width in TPC 12 correspond to symbol rates
of 160 K
SYM/SEC
. Table I shows the ACP results for the AD8325
for all conditions in DOCSIS Table 4-7
“
Adjacent Channel
Spurious Emissions.
”
Noise and DOCSIS
At minimum gain, the AD8325
’
s output noise spectral density is
10 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
SYM/SECOND
is:
20
10
160
60
48
–
2
log
nV
Hz
kHz
dBmV
×
+
=
Comparing the computed noise power of
–
48 dBmV to the
8 dBmV signal yields
–
56 dBc, which meets the required level of
–
53 dBc set forth in DOCSIS Table 4-8. As the AD8325
’
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
SYM/SECOND
is 1.0 nV/
√
Hz
or
–
68 dBmV.
Evaluation Board Features and Operation
The AD8325 evaluation board (Part # AD8325-EVAL) and
control software can be used to control the AD8325 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 AD8325 by
means of the Windows-based, Microsoft Visual Basic control
software. This package provides a means of evaluating the
amplifier by providing a convenient way to program the gain/
attenuation as well as offering easy control of the amplifiers
’
asynchronous TXEN and
SLEEP
pins. With this evaluation kit
the AD8325 can be evaluated with either a single-ended or differ-
ential 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, leave R6 and R8 open
and install a 0
chip resistor at R7. A schematic of the evalua-
tion board is provided in Figure 12.
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 AD8325 (TP6 on the evaluation
board). The evaluation board was designed to accommodate a
series resistor and shunt capacitor (R2 and C5) to filter the
CLK signal if required.
Transformer and Diplexer
A 1:1 transformer is needed to couple the differential outputs of
the AD8325 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 can be obtained
from PULSE.
Table I. ACP Performance for All DOCSIS Conditions (All Values in dBc)
160 K
SYM/SEC
320 K
SYM/SEC
640 K
SYM/SEC
1280 K
SYM/SEC
2560 K
SYM/SEC
ADJACENT CHANNEL SYMBOL RATE
TRANSMIT
CHANNEL
SYMBOL
RATE
–
66.7
–
67.6
–
62.0
–
56.3
–
54.1
–
53.8
–
55.6
–
61.1
–
67.0
–
53.1
–
53.8
–
56.0
–
61.5
–
54.3
–
53.2
–
54.0
–
56.3
–
56.3
–
54.3
–
53.4
–
54.1
–
58.5
–
56.2
–
54.4
–
53.5
160 K
SYM/SEC
320 K
SYM/SEC
640 K
SYM/SEC
1280 K
SYM/SEC
2560 K
SYM/SEC
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| AD8325-EVAL | 5 V CATV Line Driver Fine Step Output Power Control |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| AD8325ARUZ | 功能描述:IC LN DVR CATV FINE-STEP 28TSSOP RoHS:是 类别:集成电路 (IC) >> 线性 - 视频处理 系列:- 标准包装:250 系列:- 类型:电平移位器 应用:LCD 电视机/监控器 安装类型:表面贴装 封装/外壳:28-WFQFN 裸露焊盘 供应商设备封装:28-WQFN（4x4）裸露焊盘 包装:带卷 (TR) 其它名称:296-32523-2TPS65198RUYT-ND |
| AD8325ARUZ-REEL | 功能描述:IC LN DVR CATV FINE-STEP 28TSSOP RoHS:是 类别:集成电路 (IC) >> 线性 - 视频处理 系列:- 产品变化通告:Product Discontinuation 07/Mar/2011 标准包装:3,000 系列:OMNITUNE™ 类型:调谐器 应用:移动电话，手机，视频显示器 安装类型:表面贴装 封装/外壳:65-WFBGA 供应商设备封装:PG-WFSGA-65 包装:带卷 (TR) 其它名称:SP000365064 |
| AD8325-EVAL | 制造商:Analog Devices 功能描述:Evaluation Board For 5 V CATV Line Driver Fine Step Output Power Control 制造商:Analog Devices 功能描述:EVAL BD 5 V CATV LINE DRVR FINE STEP OUTPUT PWR CONTROL - Bulk 制造商:Analog Devices 功能描述:EVAL CARD ((NS)) |
| AD8326 | 制造商:AD 制造商全称:Analog Devices 功能描述:High Output Power Programmable CATV Line Driver |
| AD8326ARE | 制造商:Analog Devices 功能描述:SP Amp Line Driver Amp Single 制造商:Rochester Electronics LLC 功能描述:TSSOP HIGH OUTPUT POWER CATV LINE DRIVER - Bulk |
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