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參數(shù)資料
| 型號(hào)： | ML6421 |
| 廠商： | Fairchild Semiconductor Corporation |
| 英文描述： | Triple Phase and Sinx/x Equalized, Low-Pass Video Filter(三相和Sinx/x相均衡的視頻低通濾波器) |
| 中文描述： | 三階段和氮化硅/ x均衡，低通視頻濾波器（三相和氮化硅/ x相均衡的視頻低通濾波器） |
| 文件頁(yè)數(shù)： | 9/12頁(yè) |
| 文件大?。?/td> | 239K |
| 代理商： | ML6421 |
ML6421
9
LAYOUT CONSIDERATIONS
In order to obtain full performance from these triple filters,
layout is very important. Good high frequency decoupling
is required between each power supply and ground.
Otherwise, oscillations and/or excessive crosstalk may
occur. A ground plane is recommended.
Each filter has its own supply and ground pins. In the test
circuit, 0.1μF capacitors are connected in parallel with
1nF capacitors on V
CC
, V
CC
C, V
CC
B and V
CC
A for
maximum noise rejection (Figure 4).
Further noise reduction is achieved by using series ferrite
beads. In typical applications, this degree of bypassing
may not be necessary.
Since there are three filters in one package, space the
signal leads away from each other as much as possible.
POWER CONSIDERATIONS
The ML6421 power dissipation follows the formula:
P
(I
V
)
V
RL
3
D
CC
CC
OUT
2
=
×
×
This is a measure of the amount of current the part sinks
(current in – current out to the load).
Under worst case conditions:
P
mW
D
=
×
=
0 175 5. )
.
.
1 5
75
3
872 5
2
ML6421 VIDEO LOW PASS FILTER
Filter Selection: The ML6421 provides several choices in
filter cut-off frequencies depending on the application.
RGB: When the BW of each signal is the same, then the
ML6421-1 (5.5MHz) or ML6421-3 (8MHz) are
appropriate depending on the sampling rate.
YUV: When the luminance bandwidth is different from the
color bandwidth, then the ML6421-2 5.5MHz filter with
two 1.8MHz filters and the ML6421-4 with the 8.0, and
two 3.0MHz filters are most appropriate. The 1.8MHz
filter provides a narrower bandwidth for optimal data
compression (with MPEG and other compression
schemes), and has a time digital delay of 3.5 clock clycles
at 13.5MHz for simple digital delay compensation.
S-Video: For Y/C (S-video) and Y/C + CV (Composite
Video) systems the 5.5MHz or 8MHz filters are
appropriate. In NTSC the C signal occupies the bandwidth
from about 2.6MHz to about 4.6MHz, while in PAL the C
signal occupies the bandwidth from about 3.4MHz to
about 5.4MHz. In both cases, a 5.5MHz low pass filter
provides adequate rejection for both sampling and
reconstruction. In addition, using the same filter for both
Y/C and CV maintains identical signal timing without
adjustments.
Composite: When one or more composite signals need to
be filtered, then the 5.5MHz and 8MHz filters permit
filtering of one, two or three composite signals.
Over sampling: While the ML6421 filters can eliminate
the need for over sampling combined with digital filtering,
there are times when over sampling is used. For these
situations, 8MHz could be used in place of 5.5MHz, and
3.0MHz could be used in place of 1.8MHz.
NTSC/PAL: A 5.5MHz cut-off frequency provides good
filtering for 4.2MHz, 5.0MHz and 5.5MHz signals without
the need to change filters on a production basis.
Sinx/x: For digital video system with output D/A
converters, there is a fall-off in response with frequency
due to discrete sampling. The fall-off follows a sinx/x
response. The ML6421 filters have a complementary boost
to provide a flatter overall response. The boost is designed
for 13.5MHz Y/C and CV sampling and 6.75MHz U/V
sampling. Note: The ML6421 has the same pin-out as the
ML6420.
In a typical application the ML6421 is used as the final
output device in a video processing chain. In this case,
inputs to the ML6421 are supplied by DAC outputs with
their associated load resistors (typically 75y or 150y).
Resistance values should be adjusted to provide 2V
P-P
at
the input of the ML6421.
The ML6421 will drive 75y source termination resistors
(making the total load 150y) so that no external drivers or
amplifiers are required.
4
2
0
–2
–4
A
FREQUENCY (MHz)
0
1
2
3
4
5
6
7
THEORETICAL SINX/X
CORRECTION FOR
13.5MHz SAMPLING
SINX/X ERROR FOR
TYPICAL DAC AT 13.5MHz
Figure 5a. Sinx/x Frequency Response
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ML6423 | Dual S-Video Lowpass Filter with Phase and Sinx/x Equalization(相和Sinx/x相均衡的雙S-視頻低通濾波器) |
| ML6424 | CCIR601 Video Lowpass Filter with Optional Sinx/x Correction(可選Sinx/x校正器的CCIR601視頻低通濾波器) |
| ML6425 | CCIR601 Video Lowpass Filter with Optional Sinx/x Correction(可選Sinx/x校正器的CCIR601視頻低通濾波器) |
| ML6427 | 75W Quad Video Cable Drivers and Filters with Switchable Inputs |
| ML6427CS | 75W Quad Video Cable Drivers and Filters with Switchable Inputs |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ML6421CS-1 | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:Triple Phase and Sinx/x Equalized, Low-Pass Video Filter |
| ML6421CS1 WAF | 制造商:Fairchild Semiconductor Corporation 功能描述: |
| ML6421CS2 WAF | 制造商:Fairchild Semiconductor Corporation 功能描述: |
| ML6421CS-3 | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:Triple Phase and Sinx/x Equalized, Low-Pass Video Filter |
| ML6421CS3 WAF | 制造商:Fairchild Semiconductor Corporation 功能描述: |
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