ML6426 データシートの表示（PDF） - Micro Linear Corporation

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ML6426

High Bandwidth Triple Video Filters with Buffered Outputs for RGB or YUV

Micro Linear Corporation 

TYPICAL APPLICATIONS

RECONSTRUCTION FILTER SELECTION FOR HDTV AND

VGA SIGNAL FILTERING

The filtering requirements for HDTV and VGA standards

vary depending on the resolution of the image to be

displayed, and its refresh rate. The actual refresh rate of

the display is not necessarily the same as the transmission

rate of the frames of images. Some formats use a frame

rate of 30Hz, but the display of those formats cannot be

scanned onto the CRT at 30Hz. Excessive large area

ML6426

flicker would result. Such kinds of flicker can be seen on

a PAL display with its brightness set high. To avoid this,

the video will need to be stored in a frame buffer. This

buffer already exists in the MPEG decoder of HDTV

systems, so there is no cost penalty. The buffer is read out

at twice the rate as the frame rate for 30Hz systems, thus

getting us a refresh rate of 60Hz. Similar things are done

for the 24Hz frame rate formats to boost them to a 60Hz

refresh rate.

PIXELS

1920

1280

704

640

P=progressive scan, I=interlaced scan

VERTICAL LINES

1080

720

480

480

ASPECT RATIO

16:9

16:9

16:9 and 4:3

4:3

PICTURE TRANSMISSION RATE

60I, 30P, 24P

60P, 30P, 24P

60P, 60I, 30P,24P

60P, 60I, 30P,24P

Table 1: HDTV / Advanced TV Applications: (From Table 10.3 from ATSC document A54)

SMPTE

274M

1920

1920

1080

1080

60I

30P, 24P

60Hz

60Hz

35.3KHz

70.6KHz

81MHz

162MHz

40.5MHz ML6426-6

81MHz

N/A

SMPTE

1280

720

60P, 30P,

60Hz

24P

704

480 (Note 1)

60I

60Hz

704

480

60P, 30P,

60Hz

24P

640

480 (Note 1)

60I

60Hz

640

480

60P, 30P,

60Hz

24P

P=progressive scan, I=interlaced scan, na = not available

Note 1: NTSC display rates, can be fed directly into NTSC encoder (set top box)

Note 2: 60 Hz also includes 59.94Hz

Note 3: custom frequencies ranging ± 3 to 6MHz can be special cut to order

47.1KHz

15.7KHz

31KHz

15.7KHz

31KHz

60MHz

13.5MHz

27MHz

24.5MHz

12.27MHz

30MHz

6.75MHz

13.5MHz

12MHz

6MHz

ML6426-5

ML6426-4

ML6426-1

ML6426-2

ML6426-4

ML6426-2

ML6426-1

Table 2: Choosing the Correct Reconstruction Filter and Video Amplifier for TV Applications, ML6426 options

November, 1999

7

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