ParkerVision Eyes CDMA Designs For Direct Conversion Technology

Over the past few years, ParkerVision Inc. has spent a great deal of time developing a direct conversion technology for wireless designs. Yesterday, the Jacksonville, FL-based company claims it has taken another step in its development process. In a release, the company said it has completed a transmitter demonstration platform which proves that its Direct2Data (D2D) direct conversion platform meets the performance requirements of IS-95 CDMA designs.

First announced in December 1997, ParkerVision's D2D technology is a direct conversion (also known as zero IF) solution that allows designers to develop wireless products without the need for an IF section. According to Jeff Parker, chair and CEO of ParkerVision, engineers need to think of the product as an on-chip programmable RF matched filter for wireless designs. In a wireless design using D2D technology, information is passed from an antenna to a pre-selector to the D2D chip. The D2D chip, which houses a subharmonic clock, then passes information directly to a converter where then passed to the baseband section for processing. ParkerVision says this essentially eliminates the IF section, which includes products like surface-acoustic wave (SAW) filters in a wireless design.

According to Parker, D2D technology provides a few benefits to designers. The first benefit, he says, is improved signal-to-noise (S/N) performance. The second advantage is size and cost. By eliminating products, such as SAW filters, Parker says engineers can develop products that are smaller and consume less power. In fact, Parker says in some cases D2D technology can bring part counts from the 200 range to approximately 30 parts.

The final advantage of the product revolves around its modulation scheme support. According to Parker, D2D products can operate with any this modulation scheme, easing its implementation and use in wireless designs.

Demo Platform Achievements
ParkerVision says the D2D CDMA transmitter demonstration platform delivered a 0.9967 primary performance measurement. In addition, IS-95 adjacent channel power requirements were met with a typical 3 to 5 dB margin.

ParkerVision is currently developing a prototype D2D-based CDMA receiver demonstration platform. In addition, the company is working with a number of companies to develop a RF-to-baseband interface specification for D2D-based CDMA radios. ParkerVision intends to develop integrated RF transceiver ICs targeted at the IS-95 CDMA standard as well as other cellular standards based on its D2D technology.

For more information on the D2D technology, contact Doug Makishima of ParkerVision at 925-736-3929.

Edited by Robert Keenan