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參數(shù)資料
| 型號(hào)： | AD8120ACPZ-RL |
| 廠商： | Analog Devices Inc |
| 文件頁(yè)數(shù)： | 6/16頁(yè) |
| 文件大小： | 0K |
| 描述： | IC ANLG VIDEO DELAY LINE 32LFCSP |
| 標(biāo)準(zhǔn)包裝： | 5,000 |
| 類型： | 視頻延遲線 |
| 應(yīng)用： | HD 視頻 |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 32-VFQFN 裸露焊盤，CSP |
| 供應(yīng)商設(shè)備封裝： | 32-LFCSP-EP（5x5） |
| 包裝： | 帶卷 (TR) |
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AD8120
Data Sheet
Rev. A | Page 14 of 16
APPLICATIONS INFORMATION
Most twisted pair (TP) cables used for video transmission are
designed for data communication and typically contain four
individual TP channels. Minimization of crosstalk between pairs
is of paramount importance in data communication applications.
This is accomplished by varying the twist rates (twists per unit
length) of each pair. For a given cable length, signals traveling
on pairs with relatively high twist rates have longer distances to
traverse than signals traveling on pairs with relatively low twist
rates. The longer relative distances translate into longer relative
delays and, similarly, the shorter relative distances translate into
shorter relative delays.
The delay of any TP channel is not flat over frequency, and
an equalizer is generally used at the receiver to produce an
approximately flat delay vs. frequency characteristic as well as
an approximately flat frequency response magnitude over the
bandwidth of interest. The term “group delay” is often used in
the delay vs. frequency context. When the group delay and the
magnitude response have been corrected to the best possible
degree at the receiver, the remaining signals are close approxi-
mations to those sent at the transmit end of the cable, but with
different delays with respect to the signals sent at the transmit
end. The signals, therefore, manifest different delays relative to
each other.
The relative delay difference between any two equalized signals
at the receiver is defined as delay skew, or simply skew, and is
measured in units of time. Some bundled coaxial cables also
exhibit delay skew between channels; these skew levels are
typically much smaller than those encountered among similar
length TP channels.
The AD8120 can be used with RGB and YPbPr, as well as other
video formats. Typically, three video component signals are trans-
mitted over the TP cables, with each component carried on a pair.
For example, with RGB video signals, the red, green, and blue
signals are each transmitted over one pair. If these signals are
carried over a cable with skew larger than a quarter of a pixel
time and are displayed on a video monitor, the three colors will
not be properly aligned and the skew will be visible at the vertical
edges of objects displayed on the monitor. For fractional pixel
time skew levels, a rainbow-like effect appears at the vertical
edges of the objects; for skew levels longer than a pixel time,
vertical lines are visible on the vertical edges of objects. The
vertical lines are due to one color arriving earlier or later than
the others. The best way to observe skew is to view an object
against a black background.
The AD8120 is a triple adjustable delay line, and its primary
application is to realign the received, equalized video compo-
nents. The pixel time of UXGA video with a refresh rate of
60 Hz is approximately 6.2 ns. In this case, the 0.8 ns delay
resolution of the AD8120 represents approximately 13% of
a pixel time.
TYPICAL APPLICATION CIRCUIT FOR THE AD8123
AND AD8120
Figure 25 illustrates a complete receiver application circuit using
sync-on common mode; this circuit comprises the AD8123
triple equalizer and the AD8120. The circuit receives balanced
RGB video signals over TP cable, performs cable equalization
and skew correction, and directly drives 75 coaxial cable. The
6 dB voltage gain in the AD8120 compensates for the 6 dB double
termination loss incurred driving the coaxial cable. The low-pass
filter is optimized for short distances. Refer to the AD8123 data
sheet for details regarding the sync encoding and decoding.
The filter between the AD8123 and the AD8120 is a three-pole
low-pass filter (LPF) with a cutoff frequency of approximately
148 MHz; the LPF is included to provide high frequency noise
reduction. The filter shown in the application circuit performs
well for short to medium length cables. Note that the 1 pF capaci-
tance of each AD8120 input is added to each filter capacitor that
is connected to each AD8120 input. Thus, for the filter shown,
the actual filter capacitance at each AD8120 input is 16 pF.
For longer cables, where much greater high frequency gain is
required from the AD8123, it may be desirable to scale the LPF
bandwidth back to provide greater noise reduction. This can be
done by simply scaling the inductor and capacitor values by the
ratio of the existing cutoff frequency of 140 MHz to the desired
new cutoff frequency. For example, if a new cutoff frequency of
100 MHz is desired, the inductor and capacitor values are scaled
by a factor of (140 MHz/100 MHz) = 1.4. This is summarized in
Table 13. Low-Pass Filter Component Selection
for 100 MHz Cutoff
Original Value
Scale
Factor
New Value
Ideal
Standard
5.6 pF
1.4
7.8 pF
7.5 pF
150 nH
1.4
210 nH
220 nH
15 pF + 1 pF1 = 16 pF
1.4
22.4 pF 1 pF1 = 21.4 pF
22 pF
1
Input capacitance of the AD8120.
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| AD8120XCPZ | 制造商:Analog Devices 功能描述:TRIPLE SKEW CO - Tape and Reel |
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| AD8122ACPZ | 制造商:Analog Devices 功能描述:Differential Receiver 40-Pin LFCSP EP Tray 制造商:Analog Devices 功能描述:TRIPLE CAT5 CABLE EQUALIZER - Trays 制造商:Analog Devices 功能描述:IC RCVR TRPL DIFF EQUAL 40LFCSP 制造商:Analog Devices 功能描述:IC DIFF RECEIVER TRIPLE 40L 制造商:Analog Devices 功能描述:IC, DIFF RECEIVER, TRIPLE, 40LFCSP 制造商:Analog Devices Inc. 功能描述:Equalizers Trple Diff Rcvr w/ 300m Adj Cble 制造商:Analog Devices 功能描述:LINE DRIVER, DIFFERENTIAL, 3DRIV, LFCSP-40; No. of Drivers:3; MSL:MSL 3 - 168 hours ;RoHS Compliant: Yes |
| AD8122ACPZ-R7 | 制造商:Analog Devices 功能描述:Differential Receiver 40-Pin LFCSP EP T/R 制造商:Analog Devices 功能描述:TRIPLE CAT5 CABLE EQUALIZER - Tape and Reel 制造商:Analog Devices 功能描述:IC RCVR TRPL DIFF EQUAL 40LFCSP 制造商:Analog Devices Inc. 功能描述:Equalizers Trple Diff Rcvr w/ 300m Adj Cble |
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