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參數(shù)資料
| 型號： | TDA9181 |
| 廠商： | NXP Semiconductors N.V. |
| 英文描述： | Integrated multistandard comb filter |
| 中文描述： | 集成多標準梳狀濾波器 |
| 文件頁數(shù)： | 5/32頁 |
| 文件大?。?/td> | 135K |
| 代理商： | TDA9181 |
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2000 Nov 22
5
Philips Semiconductors
Objective specification
Integrated multistandard comb filter
TDA9181
FUNCTIONAL DESCRIPTION
Input configuration
The Y/CVBS
1
and Y/CVBS
2
input signals are clamped by
means of an internally generated clamp pulse which is
derived from the sandcastle input signal (pin SC). If no
sandcastlesignalisavailable,aclamppulsesignalmaybe
applied to pin SC. External clamp capacitors are needed.
The buffered and clamped Y/CVBS
1
and Y/CVBS
2
signals
arethenappliedtotheinputswitch.Theinputswitchselect
signal (INPSEL) determines whether Y/CVBS
1
or
Y/CVBS
2
ispassedthroughtotheanti-aliaslow-passfilter.
This 3rd-order low-pass filter is optimized for best
performance with respect to step response and clock
suppression. The filtered signal is sampled at a clock
frequency of four times the colour subcarrier frequency
(f
SC
).
A colour subcarrier frequency signal is applied to pin FSC.
The colour subcarrier select input signal (FSCSEL)
indicates whether the colour subcarrier frequency (f
SC
) or
twice the colour subcarrier frequency (2
×
f
SC
) is being
applied at the FSC input. An external coupling capacitor is
needed for the colour subcarrier input signal.
Comb filter
The sampled CVBS signal is applied to two delay lines.
Depending on the applied standard, one delay line delays
the signal over 1 or 2H for NTSC and PAL respectively
(1H = oneline-time).ThestandardselectinputsSYS1and
SYS2 indicate which standard, PAL B, G, H, D, I, M, N or
NTSC M, is being applied.
The direct and delayed signals are applied to an adaptive
comb filter. The adaptive comb filter performs band-pass
filtering around the colour subcarrier frequency and
compares the contents of adjacent lines. In this way the
combing of signals with different information is prevented
and artifacts such as hanging dots are avoided.
Boththe combed chrominance and the combed luminance
signals are passed through a reconstruction low-pass filter
to obtain continuous-time signals. These low-pass filters
are 3rd-order, optimized for best performance with respect
to step response and clock suppression. The
reconstructed signals are applied to the output switches.
Output configuration
The luminance output switch selects between the
reconstructed combed luminance signal and one of the
bufferedandclampedinputsignals,Y/CVBS
1
orY/CVBS
2
.
The chrominance output switch selects between the
reconstructed combed chrominance signal and the
chrominance input signal (C
IN
). An external coupling
capacitor is needed for C
IN
. The selected signals are
applied to the outputs Y/CVBS
OUT
and C
OUT
respectively
via a buffer stage. The output switch signal (OUTSEL)
determines whether the output switches select the internal
combed signals or the external Y/C signals.
Clock generation and filter tuning
The clock generator is driven by a Phase-Locked Loop
(PLL)circuitwhichgeneratesareferencefrequencyoffour
times the colour subcarrier frequency. This PLL circuit is
phase-locked to the colour subcarrier input signal (FSC).
Several internal clock signals are derived from the 4
×
f
SC
reference.
The filter tuning ensures the automatic alignment of the
anti-alias and the reconstruction low-pass filters. A 4
×
f
SC
clock signal is used as a reference for the alignment. The
tuning takes place each line during the line blanking and is
initiated by means of an internally generated signal which
is derived from the sandcastle input signal.
If the output switches select external Y/C signals the
oscillator of the PLL circuit is stopped regardless of the
FSCinputandnointernalclocksignalsaregenerated.The
filter tuning is also stopped.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TDA9181P | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Integrated multistandard comb filter |
| TDA9181T | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Integrated multistandard comb filter |
| TDA9183 | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Integrated NTSC comb filter |
| TDA9183P | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Integrated NTSC comb filter |
| TDA9183T | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Integrated NTSC comb filter |
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