- 您现在的位置：买卖IC网 > PDF目录373943 > AD8321AR-REEL (ANALOG DEVICES INC) Gain Programmable CATV Line Driver PDF资料下载
参数资料
| 型号： | AD8321AR-REEL |
| 厂商： | ANALOG DEVICES INC |
| 元件分类： | 通用总线功能 |
| 英文描述： | Gain Programmable CATV Line Driver |
| 中文描述： | LINE DRIVER, PDSO20 |
| 封装： | MS-013AC, SOIC-20 |
| 文件页数： | 11/19页 |
| 文件大小： | 660K |
| 代理商： | AD8321AR-REEL |
AD8321
–11–
REV. 0
Distortion and DOCSIS
Care must be taken when selecting attenuation levels specified
in Table I as the output signal from the AD8321 must compen-
sate for the losses resulting from any added attenuation as well
as the insertion losses associated with the diplexer. An increase
in input signal becomes apparent at the upper end of the gain
range and will be needed to achieve the 58 dBmV at the mo-
dem output. The insertion losses of the diplexer may vary,
depending on the quality of the diplexer and whether the fre-
quency of operation is in near proximity to the cut-off fre-
quency of the low-pass filter. Figures 9 and 10 show the
expected second and third harmonic distortion performance vs.
fundamental frequency at various input power levels. These
graphs indicate the worst harmonic levels exhibited over the
entire output range of the AD8321 (i.e., –27 dB to +26 dB).
Figures 9 and 10 are useful when it is necessary to determine
inband harmonic levels (5 MHz to 42 MHz or 5 MHz to
65 MHz). Harmonics that are higher in frequency, as compared
to the cutoff frequency of the low-pass filter of the diplexer, will
be further suppressed by the stop band attenuation level of the
LP filter in the diplexer. Designers must balance the need to
improve noise performance by adding attenuation with the
resulting need for increased signal amplitude while maintaining
DOCSIS specified distortion performance.
Evaluation Board Features and Operation
The AD8321 evaluation board (p/n AD8321-EVAL) and com-
panion software program written in Microsoft Visual Basic are
available through Analog Devices, Inc. and can be used to
control the AD8321 Variable Gain Upstream Power Amplifier
via the parallel port of a PC. This evaluation package provides a
convenient way to program the gain/attenuation of the AD8321
without the addition of any external glue logic. AD8321-EVAL
has been developed to facilitate the use of the AD8321 in an
application targeted at DOCSIS compliance. A low cost Alpha
Industries AS128-73 GaAs 2 Watt High Linearity SPDT RF
switch (referred to as SWb) is included on the evaluation board
(see Figure 28) along with accommodations for a user specified
75
matching attenuator (See Table I for a table of resistor
values of attenuators ranging from –1 dB to –4 dB). The
AD8321
DATEN
, CLK and SDATA digital lines are pro-
grammed according to the gain setting and mode of operation
selected using the Windows
interface of the control software
(see Figure 30). The serial interface of the AD8321 is ad-
dressed through the parallel port of a PC using four or more
bits (plus ground). Two additional bits from the parallel port
are used to control the RF switch(s). This software programs
the AD8321 gain or attenuation, incorporates asynchronous
control of the power-down feature (
PD
Pin 6) as well as asyn-
chronous control of the Alpha Industries RF switch(es) AS128-
73.* A standard printer cable is used to feed the necessary data
to the AD8321-EVAL board. These features allow the designer
to fully develop and evaluate the upstream signal path begin-
ning at the input to the PA.
Overshoot on PC Printer Ports
The data lines on some PC parallel printer ports have excessive
overshoot. Overshoot presented to the CLK pin (TP7 on the
evaluation board) may cause communications problems. The
evaluation board layout was designed to accommodate a series
resistor and shunt capacitor (R6 and C12) if required to filter or
condition the CLK data.
Between Burst Transient Reduction
In order to reduce the amplitude of the “Burst On/Off Tran-
sient” glitch at the output of the AD8321, when switching from
forward transmit mode to reverse powered down mode, position
the SWb switch in Figure 28 to position “a” before changing the
logic applied to
PD
Pin 6 of the AD8321 from Logic 1-to-0
(and also 0-to-1). Use the “Enable Output Switch” feature in
the evaluation board control software (see Figure 31) to select
the appropriate position of the AS128-73 switch. A check in this
box enables the switch to pass upstream data to the output of
the evaluation board. The AS128-73 produces a glitch of ap-
proximately 5 mV p-p regardless of the AD8321 gain setting.
The AD8321-EVAL board comes with resistors and capacitors
installed on the logic lines controlling the RF switch (R8, R9,
C16, C17). These values were selected to reduce the glitch
amplitude to DOCSIS acceptable levels and may be modified if
required. The SPDT function of the AS128-73 RF switch ac-
commodates the need to maintain proper termination when the
diplexer is disconnected from the output of the AD8321. The
AD8321-EVAL board accommodates the needed back termina-
tion (refer to the Cb and Rb of the evaluation circuit).
Differential Inputs
When evaluating the AD8321 in differential input mode, termi-
nation resistor(s) should be selected and applied such that the
combined resistance of the termination resistor(s) and the input
impedance of the AD8321 results in a match between the signal
source impedance and the input impedance of the AD8321. The
evaluation board is designed to accommodate Mini-Circuits T1-
6T-KK81 1:1 transformer for the purposes of converting a
single-ended (i.e., ground referenced) input signal to differen-
tial inputs. The following paragraphs identify three options for
providing differential input signals to the AD8321 evaluation
board. Option 1 uses a transformer to produce a truly differen-
tial input signal. The termination resistor(s) specified in Option
1 and 2 may also be used without the transformer if a differen-
tial signal source is available. Option 2 uses a transformer and-
produces ground referenced input signals that are separated in
phase by 180
°
. Option 3 relies on differential signals provided
by the user and does not employ a transformer for single-to-
differential conversion.
Differential Input Option 1:
Install the Mini-Circuits T1-6T-
KK81 1:1 transformer in the T1 location of the evaluation
board. Jumpers J1, J2 and J3 should be applied pointing in the
direction of the transformer. A differential input termination
resistor of 82.5
can be used in the R3 position. This value
should be used when the single-ended input signal has a source
impedance of 75
. In this configuration, the input signal must
be applied to the VIN+/DIFF IN port of the evaluation board.
An open circuit is required in R1, R2 and J4 positions resulting
in a 75
differential input termination to the AD8321. If a
50
single-ended input source is applied to the VIN+/DIFF IN
port, the R3 value should be 53.6
.
Windows is a registered trademark of Microsoft Corporation.
*Alpha Industries @ www.alphaind.com
相关PDF资料 |
PDF描述 |
|---|---|
| AD8321-EVAL | Gain Programmable CATV Line Driver |
| AD8321AR | Gain Programmable CATV Line Driver |
| AD8322ARU-REEL | 5 V CATV Line Driver Coarse Step Output Power Control |
| AD8322-EVAL | 5 V CATV Line Driver Coarse Step Output Power Control |
| AD8322ARU | 5 V CATV Line Driver Coarse Step Output Power Control |
相关代理商/技术参数 |
参数描述 |
|---|---|
| AD8321ARZ | 功能描述:IC LINE DRIVER CATV 3.3V 20SOIC 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 |
| AD8321ARZ2 | 制造商:AD 制造商全称:Analog Devices 功能描述:Gain Programmable CATV Line DRiver |
| AD8321ARZ-REEL | 功能描述:IC LINE DVR CATV 20-SOIC T/R 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 |
| AD8321ARZ-REEL2 | 制造商:AD 制造商全称:Analog Devices 功能描述:Gain Programmable CATV Line DRiver |
| AD8321-EVAL | 功能描述:BOARD EVAL FOR AD8321 RoHS:否 类别:编程器，开发系统 >> 评估演示板和套件 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:- 主要目的:电源管理，电池充电器 嵌入式:否 已用 IC / 零件:MAX8903A 主要属性:1 芯锂离子电池 次要属性:状态 LED 已供物品:板 |
发布紧急采购，3分钟左右您将得到回复。