Rohm Co., Ltd., has developed a high-performance video driver series for DVD players and recorders. A dedicated filter block consisting of all required filters for DVD video signal processing, 6-dB amp, and 75-ohm driver have been integrated in a single chip for the first time in the industry.

The models constituting this series are the BH7862FS and BH7860FP. The BH7862FS has 6 built-in channels (Y, C, MIX, PY, Pb, and Pr signals) and is designed for high-end DVD equipment compatible with progressive scanning. The BH7860FP has 5 built-in channels (Y, C, MIX, Cb, and Cr signals) and is intended for low-end DVD equipment.

As DVD equipment has become very popular recently, the demand is growing for higher-quality images. A feature of the DVD video driver series newly developed by Rohm is the dedicated built-in filter capable of almost completely eliminating clock noise, which is considered to affect image quality, from the D/A pre-converter.

This dedicated filter has an excellent frequency response suitable in various video signal bands. The conventional filter is a simplified one that works in all signal bands, but is incapable of sufficient attenuation at the clock rate of 27 MHz, and therefore can only provide limited clock noise elimination capability. Each model of the newly developed series contains the dedicated combination filter consisting of a trap filter, band-pass filter, and low-pass filter. This combination filter completely removes clock noise and unwanted high-frequency components, thereby contributing to improved image quality of DVD equipment. Rohm's original circuit technology is used to control group delay characteristics between Y and color-difference signals, which are caused by the dedicated filter, to several nanoseconds, thereby successfully preventing degradation in image quality caused by color shift.

Rohm has carved out a nice slice of business with ASIC blocks dedicated to various areas of video and audio. These ICs, further examples of that, have carefully controlled filter characteristics with detailed corrections for group delay errors created by the filters themselves, but using filter technology to do so. The parts can be used as the video output device with the correct drive levels and able to drive two channels with each signal into double-terminated 75 ohm lines.

What Rohm describes as the lower-end product, the BH7860FP, is still provided with component channels so it is at the high-end of most users today who are still wasting enormous picture quality benefits by running Y/C -- or even composite; that will probably continue to happen while A/V dealers prefer their staff to sell particular brands and models of receiver. There are, in addition to the internal filters, pins provided for the addition of external filter components to improve the clock rejection performance even further. The supply voltage is 5 V.