Analog video interfaces are essential components of digital home and personal entertainment systems. This is mainly due to their ability to deliver very high image quality with very low power consumption while maintaining compatibility with most modern and earlier-generation video devices where analog video interfaces are the prevalent video interface. In the past, analog video interfaces were implemented using external components. With the proliferation of richer multimedia content in advanced consumer electronics such as DVD players, digital TVs and set-top boxes, integrating high-speed analog interface intellectual property (IP) including analog video interfaces and other multimedia analog and digital interfaces into systems-on-chip (SoCs) has become critical to achieve the necessary processing power and image quality.
Video formats can be divided into the following resolution categories: standard TV (PAL, NTSC, etc.), HDTV (e.g., 1080p) and widescreen VGA formats (e.g., 1920x1200) for PC graphics. All of these formats require the accurate transmission of color, brightness and synchronism information over a long cable. To accomplish this, the video transmitter must be able to transmit the video signal reliably and independent of the quality of the transmission cable. Conversely, the receiver must be able to accurately receive the signal and decode the synchronism information in order to re-create a high-quality image.
Maintaining competitiveness in today's consumer electronic products market requires integrating increased functionality into the same digital SoC, which, in turn, poses key design challenges in terms of power dissipation, form-factor reduction and ability to handle multiple video sources.
This two-part series discusses implementation of analog video interfaces that can be embedded into complex SoCs. Part one focuses on the transmitter part of the analog video interface, which is essentially a digital-to-analog converter with video performance, and discusses the characteristics of the source and of the transmission medium. Part two of this article provides a detailed review of the receiver part of the analog video interface, which is based on a video analog front-end. Key characteristics will be covered, highlighting the special features embedded into the IP that allow it to recreate a high-quality image on the destination side.
Particular emphasis is placed on the features embedded into the IP that provide SoC designers with high-quality, low-power and compact-area video solutions. These analog IP components can be easily integrated into a wide variety of SoCs that target video electronic products, making them an advantageous alternative to external components.
Home entertainment video-rendering equipment typically spans several technological generations. In order to guarantee both interoperability between all the equipment and high video quality, modern home entertainment equipment must support multiple types of video standards. A quick look at the back of a typical set-top box or DVD player will reveal a number of different connectors that correspond to the different ways analog video signals are transmitted. For example, there may be a VGA connector, a triple-component video RCA connector, a component video connector, an S-video DIN connector and, depending on the region, a SCART connector. In spite of the various connectors normally featured in video devices, a single signal source that is routed to the connector is desirable from a system-cost point of view. This single source must be able to transmit without compromising the signal integrity of any of the video formats, from the narrowband SDTV standards (PAL, NTSC, SECAM) to the broadband HDTV and VGA graphics video formats. Furthermore, the quest for cost reduction and product differentiation mandate that the video transmitter be integrated into the digital video encoder SoC.