THS8200IPFP Datasheet, PDF (32/104 Pages) Texas Instruments – All-Format Oversampled Component Video/PC Graphics D/A System

THS8200-EP
SLES253 – DECEMBER 2009
www.ti.com
Figure 4-12 through Figure 4-14 illustrate the frequency and phase responses of the interpolating filters.
The actual response using the finite-word length coefficients present in THS8200 is shown. The same
filter characteristic is used for SDTV/HDTV modes and for both 4:2:2 to 4:4:4 interpolation (2 filters, one
on each of Cb and Cr channels, switched in when a 4:2:2 input mode is selected on DMAN to interpolate
chrominance from 1/2 to 1× pixel clock rate) as well as for 2× video oversampling (3 filters, one on each
DAC channel, switched in when 2× interpolation is activated).
xxx
0
0.01
10
0.0089
20
0.0086
0.0074
30
0.0062
40
05
50
0.0042
60
0.0043
70
0.0062
80
0.0081
90
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
f - Frequency - Rad
Figure 4-12. IFIR Frequency Response
4
0.0010.00
0.25
0.50
0.75
1.00 1.25
1.50
f - Frequency - Rad
Figure 4-13. IFIR Pass-Band Frequency Response
3
2
1
0
1
2
3
40.0
0.5
1.0
1.5
2.0
2.5 3.0
f - Frequency - Rad
Figure 4-14. IFIR Phase Response
Each of the two interpolation stages can be switched in or bypassed:
• Register data_ifir12_bypass controls the 4:2:2 to 4:4:4 filter bank (these filters should be set active
when a 4:2:2 input mode is selected on DMAN).
• Register data_ifir35_bypass controls the 1× to 2× interpolation stage and can be set active for optional
2× interpolation when an input format with pixel clock < 80 MSPS is present.
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Detailed Functional Description
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