Harris' New CMOS D/A Converter Couples High Performance With Low Power

October 12, 1998

-bit, 125MSPS D/A Converter is designed for +3V or +5V  operation while maintaining superb AC performance

MELBOURNE, FL, October 12, 1998 — The combination of telecommunication deregulation and the popularity of the graphics-rich Internet has increased the need for broadband access to the home. To satisfy this need, various cable modem and phone modem manufacturers are introducing new products to deliver broadband access to the home. Designers of these products can now rely on a new digital-to-analog (D/A) converter by Harris Semiconductor to meet the specifications of the cable modem’s upstream communication channel.

The HI5760 10-bit, 125MSPS D/A converter enhances a cable modem’s upstream communication of data, voice and video by providing wide Spurious Free Dynamic Range and low Harmonic Distortion (73dBc typ & 76dBc typrespectively@fclk = 50MSPS, fout = 1MHz).

The HI5760 consumes less power, costs less and is available in SOIC& TSSOP packages. The part consumes only 165mW@5volts and has a power down mode, where it consumes only 9.3mW@3volts. The user can eliminate a bypass capacitor on the COMP2 pinof the HI5760 to save cost and board space.

Price and Availability

Packaged in 28-lead SOIC and TSSOP*, the HI5760BIB is available from stock for $8.80 in quantities of 100s. An evaluation board (HI5760EVAL1) is available from Harris or authorized distributors.

Wired Applications

The 10-bits of accuracy and clean spectral performance of Harris’ HI5760 serves a number of key communication applications. Cable modems, where high speed DSP is linked to high-speed A/D and D/A converters (for receive &transmit), provide the interactive features serious web surfers demand. The HI5760 is employed in reconstructing a high-speed baseband signal or even the high frequency modulated signal. This eliminates costly intermediate step-up (or IF) stages, reducing system complexity, size and power consumption.

Today’s cable modems use a QAM modulation scheme for video, voice and data in the downstream path to the home while a QPSK (& 16 QAM) scheme isused in the upstream path to the headend. To meet the Multimedia Cable Network System(MCNS) specifications the upstream is implemented with a QPSK/QAM modulator and a highspeed D/A converter with good spectral performance. The HI5760 boasts a high level of, ensuring that a cable modem or STB meets or exceeds the MCNS specification. To support the European market, a 165MSPS version will be available in 2H98.

Wireless Applications

As part of the communications infrastructure of the future, wireless systems like cellular and wireless local loop are being used to complement terrestrial systems. Wireless base-stations use several protocols (AMPS, TDMA, CDMA, wide-band CDMA, etc.) to transceive both data and voice. Base-station transceivers rely on pure spectral operation to transmit a signal onto an encrypted spread spectrum carrier. High performance D/A converters, like the HI5760, are used in the transmit side with a digital upconverteror an NCO.

Harris Signal Processing Focus

The HI5760 family is an example of Harris Semiconductor's company-wide focus on high-speed signal processing as applied to communication applications. The Harris D/A converter line covers the resolution scale from 8- to 14-bits and from 20 to 160MSPS. In addition to data converters, Harris addresses the entire signal processing chain with a portfolio of linear, mixed-signal, DSP ICs optimized for high-speed and multimedia application-specific products. End-markets include video and image processing, high-speed communications, and test and measurement equipment.

Harris Corporation's Semiconductor sector manufactures discrete semiconductors and integrated circuits and focuses research and development efforts on innovative new products for the communications and power control markets. Harris Corporation, with worldwide sales of more than $3.9 billion, is an international communications and electronics company that provides a wide range of products and services, such as wireless and personal communications, digital television (HDTV), healthcare information, automotive electronics, transportation, business information, defense communications and information and Lanier office products.

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For additional information contact Harris Corporation at webmaster@harris.com.