Wednesday, February 18, 2009

Analog Reconstruction Filter for HDTV Using the THS8133, THS8134, THS8135, THS8200

The THS8133, THS8134, THS8135, and the THS8200 devices are part of a family of chips for graphics and video applications, which contain triple DACs that operate up to 240 MSPS. For television applications, an analog low-pass filter is required to reconstruct the signal that is input to the monitor. High definition television (HDTV) requires a sampling frequency of 74.25 MHz and has pass-band, transition-band, and stop-band attenuation requirements, which affect the complexity of the filter. A higher sampling rate results in a lower filter complexity.

The THS8133, THS8134, THS8135, and THS8200 comprise a family of graphics/video chips that have triple digital-to-analog converters (DACs) that convert digital graphics signals GBR/YPbPr to analog. They insert bilevel or trilevel syncs into the green/luma signal. The trilevel sync is used for horizontal synchronization of high definition (HD) television signals. Table 1 lists the chips and their capabilities. The THS8200 incorporates a 1:2 upsampling and interpolation filter, which results in a simplification of the filter design that is used to reconstruct the analog output signal. The advantages of 2x oversampling are examined for the high definition (HD) television application.

Get pdf download Analog Reconstruction Filter for HDTV Using the THS8133, THS8134, THS8135, THS8200

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