Panasonic PT-50LCX63: HDTV's analog ending

Three high-resolution LCD panels"one for each of the red, green, and blue primary colors"generate the final picture. A high-intensity lamp is collimated, split, and color-filtered to pass through each of the LCDs which act as light valves for modulating the desired on-screen image. A series of complex prisms and lenses recombines the output of the LCD panels and projects them via a reflecting mirror onto the large front screen panel, itself a trick piece of optics engineering.

Driving the LCD panels remains the key piece of analog artistry. Supplying information to refresh the high-resolution picture around 30 times per second while accommodating 16.7 million colors means a whole lot of data. Back on the main system board"not shown"a National Semiconductor Low Voltage Differential Signaling (LVDS) driver (#DS90C385MTD) sends serialized RGB data to the LCD driver board at a blazing 1.4Gbits/sec. While LVDS is a digital transmission, mixed-signal finesse is needed to reliably transmit the high-speed bit stream, in essence a wideband analog signal-integrity challenge.

Once data arrives on the LCD board, a National Semiconductor LVDS Receiver (#DS90CF386NTD) recreates a 24-bit parallel data stream for delivery to a Kawasaki ASIC. The Kawasaki chip (#E07050K0B) shuttles data to a set of 10-bit high voltage D-A converters from Analog Devices (#AD8383) which directly interface to the LCD panels as shown with the red arrows. With such a huge color palette, precise control of the analog signal levels driving the LCDs is critical to keep hues, brightness, and uniformity all up to spec.

At $2500 or more the Panasonic isn't cheap, but in the end this digital TV relies on analog technology to get the picture to the finish line and serve up a beautiful viewing experience.

David Carey is President of Portelligent. The Austin, Texas company produces teardown reports and related industry research on Wireless, Mobile, and Personal Electronics. (www.teardown.com)