- SS-HQ1 Application Notes -
Ver.1.0.0 January 7, 2005
25
3.7. External LPF
3.7.1. Outline
The CXD3172AR contains an LPF with improved characteristics, so sufficient performance can be obtained
even if an LPF is not connected to the luminance signal output pin IOY (pin 75).
3.7.2. High Resolution and LPF
The characteristics of the CXD3172AR’s internal LPF have been improved, so high resolution can be obtained
without connecting an external LPF. Conversely, connecting an external LPF makes it impossible to obtain high
resolution due to attenuation of the luminance signal.
3.8. Example Characteristics and Circuit for External BPF
3.8.1. Outline
In cases where the CXD3172AR’s chroma signal output pin IOC (Pin 67) is used, add a band-pass filter circuit
to ensure that signal components other than the sub-carrier component are removed. This circuit also shapes
the sub-carrier signal, in which digital components remain, into a sine wave.
3.8.2. BPF Circuit Example
indicates BPF Circuit Example.
Fig 3.8-1 BPF Circuit Example
CXD3172AR
IOC(67pin)
220
3.3k
NTSC:68pF
PAL :33pF
470
68uH
2.2k
Y/C MIX
VIDEO AMP
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