Over-sampling A/D converting circuit
AssigneeNEC Electronics Corporation
InventorYasunori Tashiro
Life of this patent
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Abstract
To provide an A/D converting circuit capable of improving an S/N ratio regardless of a color television system. An over-sampling A/D converting circuit according to an embodiment of the present invention includes: an A/D converter for over-sampling an analog video signal; a digital low-pass filter allowing passage of a signal component in a predetermined passing band out of the over-sampled signal; a down-sampling circuit for down-sampling the passed signal; and a color television system determining circuit for switching the passing band.
Claims14
An over-sampling A/D converting circuit, comprising:
- an input receiving an analog video signal;
- and
- a filter unit limiting a frequency band of the analog video signal in accordance with a sampling frequency that varies depending on a color television system of the analog video signal,
- wherein the filter unit includes a plurality of frequency band limiting filters each having a predetermined passing band based on the sampling frequency in accordance with the color television system, the frequency band limiting filter suitable for the sampling frequency being selected from among the plurality of frequency band limiting filters.
An over-sampling A/D converting circuit, comprising:
- a first sampling unit executing A/D conversion on an input analog video signal with a first sampling frequency;
- a frequency band limiting filter unit allowing passage of a signal component in a predetermined passing band out of a signal passing through the first sampling unit;
- a second sampling unit sampling the passed signal with a second sampling frequency;
- and
- a switching unit switching the passing band of the frequency band limiting filter unit,
- wherein the switching unit determines a color television system of the analog video signal based on the signal sampled with the second sampling frequency to switch the passing band of the frequency band limiting filter unit in accordance with the determined color television system.
A method of sampling an analog video signal, comprising:
- receiving the analog video signal;
- and
- limiting a frequency band of the analog video signal in accordance with a sampling frequency that varies depending on a color television system of the analog video signal,
- wherein the limiting step comprises:
- passing the analog video signal through a filter unit that includes a plurality of frequency band limiting filters each having a predetermined passing band based on the sampling frequency in accordance with the color television system;
- and
- selecting a frequency band limiting filter suitable for the sampling frequency from among the plurality of frequency band limiting filters.
Dependencies are inferred from the claim text.