Multimedia Reconstruction Filters
FL476 / FL477 Low Cost
These filters are designed to be used with Half-band Interpolating/Decimating digital filters, for example the
TRW TMC2242, or with devices employing an output D/A which incorporates digital filters such as the
TRW Digital Video Encoder TMC22190.
The digital filters have good attenuation between the frequencies of Fs/4 and 3Fs/4 where Fs is the PXCK
(Master clock) rate and, combined with double speed oversampling, this simplifies the specification for the
analogue reconstruction and antialiasing pre filters as when the normal PXCK rate of 27 MHz is used there
is little signal energy between 6.75 MHz and 20.25 MHz.
To reconstruct the analogue signal an additional filter is required to attenuate the clock frequency and its
sidebands.
To preserve the integrity of the signal the analogue filter must have a passband similar to the requirement of
CCIR rec 601 but it does not need significant attenuation below 21 MHz.
An additional feature in the Faraday filters is a zero at 27 MHz to maximise suppression at the PXCK rate.
Sinx/x correction may be added by grounding one pin in the device.
© Faraday Technology. As part of continual product improvement the specifications, details and dimensions shown in this publication are subject to change
without notice
FARA053d
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FARADAY [ FARADAY TECHNOLOGY ]
