TW9920
Multi-Standard Video Decoder and Encoder
Typical Diagram
Key Features
- Video Decoder
- NTSC (M, 4.43) and PAL (B,D, G, H, I, M, N,N combination), PAL (60),SECAM support with automatic format detection
- Software selectable analog inputs allows any of the following combinations, e.g. 4 CVBS or (3 CVBS and 1 Y/C ).
- Two 9-bit ADCs and analog clamping circuit.
- Fully programmable static gain or automatic gain control for the Y channel
- Programmable white peak control for the Y or CVBS channel
- 4-H adaptive comb filter Y/C separation
- PAL delay line for color phase error correction
- Image enhancement with 2D peaking and CTI.
- Digital sub-carrier PLL for accurate color decoding
- Digital Horizontal PLL for synchronization processing and pixel sampling
- Advanced synchronization processing and sync detection for handling non-standard and weak signal
- Video Encoder
- Support NTSC/PAL and its sub-standard format output
- ITU-R 656 compatible video interface
- Luminance and chrominance filter
- Stable 27MHz crystal clock for subcarrier generation
- Five 10-bit Digital-to-Analog Converters at 27MHz sample rate for generating CVBS or Y/C and YcbCr simultaneously
Description
The TW9920 is a multi-standard video decoder and encoder chip that is designed for multimedia applications. It uses the mixed-signal 2.5V CMOS technology to provide a low-power integrated solution.
The video encoder is used to encoder digital YcbCr input into analog CVBS or S-video output. With five built-in DACs, it can simultaneously support analog YcbCr output in addition to S-video output for various applications.
It can support both NTSC (60Hz) and PAL (50Hz) output. A stable crystal generated 27MHz clock is used for all necessary sub-carrier generation. It accepts ITU-R 656 compatible digital input externally. The video decoder decodes the analog CVBS or
S-video signals into digital YcbCr for output.
It consists of analog front-end with input source selection, variable gain amplifier and analog-to-digital converters, Y/C separation circuit, multistandard color decoder (PAL BGHI, PAL M, PAL N, combination PAL N, NTSC M, NTSC 4.43 and SECAM) and synchronization circuitry.The Y/C separation is done with highly adaptive 4H comb filter for reduced cross color and cross luminance.
The advanced synchronization processing circuitry can produce stable pictures for
non-standard signal as well as weak signal. A video scaler is provided to arbitrarily scale down the output video. The output of the decoder is formatted to the ITU-R 656 compatible output.
It includes various control circuits like brightness, contrast, saturation, dynamic aperture correction for best video quality. A 2-wire serial MPU interface is used to simplify system integration. All the functions can be controlled through this interface.
Applications
- Digital Camcorder
- Portable Media Player (PMP)
- Mobile Phone and PDA
