New video filters are being developed to make life easier for design engineers
by integrating the functions once implemented with discrete components. The new
products are said to cost less, save space and perform better since the
proximity of video functions on the IC reduces parasitic capacitance.
These devices are emerging in response to growing demand for high-definition
digital television (HDTV) applications, cable and satellite set top boxes
(STBs), DVD players, personal video recorders (PVRs), video on demand (VoD) and
Fairchild Semiconductor (South Portland, Maine) released the FMS6403 filter,
which is selectable for standard definition (SD), progressive scan (PS) or
high-definition (HD standards offering tri-level sync and a bypass mode that
permits the passing of 1080 pixel and HDTV signals. This highly integrated tiny video filter features true 2:1 mux inputs for YPbPr or RGB inputs, and triple 6th order filters with selectable 30 MHz, 15 MHz or 8
MHz-cutoff frequencies. It can accommodate the full range of worldwide video
formats for DVD players, set-top boxes and HDTVs. The video filter can be used
in two ways. Its most common function is as an anti-aliasing filter to remove
high-frequency noise prior to A/D conversion. It can also be used as a
reconstruction filter to remove high-frequency artifacts introduced during D/A
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Block Diagram of Fairchild's FMS6403
Also able to condition HD as well as SD video signals, Analog Devices Inc.'s
(Norwood, Mass.) newest monolithic IC video filter devices replace dozens of
passive components, amplifiers, and muxes with a single chip.
Just think of the MAX7454 and MAX7455 triple switchable video reconstruction
filters and buffers as the aspirin you can avoid by using Maxim Integrated
Products Inc.'s (Sunnyvale, Calif.) devices, instead of designing your own
filters and buffers using some 40 to 50 different discrete components.
Highly integrated video filters like these weren't available until recently.
Historically, several discrete components, which might include high-speed
amplifiers like National Semiconductor Corp.'s new 1.2-GHz op amp, or triple
multiplexing amplifiers from either Intersil Corp. or Linear Technology Corp.
would have been used to achieve the same functionality.
National Semiconductor (Santa Clara, Calif.) claims that its LMH6703 is the
industry's most stable 1.2-GHz operational amplifier for high-speed signals.
Intersil Corp.'s (Milpitas, Calif.) highly-integrated triple multiplexing amplifiers for switching
high-resolution RGB or HDTV signals are said to easily support ultra extended
graphics array (UXGA) resolutions a display spec that is capable of displaying
1600 x 1200 resolution or roughly 1.9 million pixels.
The LT6555 multiplexer from Linear Technology Corp. (Milpitas, Calif.) is said
to enable sharper video images. Achieving beyond UXGA quality resolution, the
device is intended for use in high-resolution video with multiple inputs or
outputs. The 2:1 input multiplexers simplify the selection of two video signals
while the internal fixed gain of two amplifiers eliminates external gain setting
resistors when driving 75Ω back-terminated cables.
The device offers a wide bandwidth of 650 MHz and a very high slew rate of
2200V/μs, allowing it to process large input signals. This, coupled with a quick
6.5-ns settling time, enhances the AC performance, resulting in sharper video
images, according to Tim Regan, applications manager at Linear Technology. ”