A Short History of ParkerVision D2D
In 1997, ParkerVision announced a new receiver technology which it called D2D (for Direct 2 Digital). That same year, Jeff Parker announced a deal with IBM (later canceled.)
In 1999, there were discussions between ParkerVision and Qualcomm about licensing D2D. The negotiations eventually failed by the end of 1999, after extensive testing by Qualcomm showed that the ParkerVision receiver did not meet CDMA specifications. Every other announced licensee of D2D has also abandoned the technology.
In 2011, ParkerVision sued Qualcomm for patent infringement, claiming that Qualcomm “stole” D2D technology that Qualcomm learned during 1999. In response, Qualcomm claims that the patent claims are invalid and should never have issued. The obvious question becomes what was “D2D technology” and what was ParkerVision selling during the 1999 negotiations.
According to ParkerVision documents and press releases, D2D has always used a sub-harmonic clock (N>1, from the Markman). There are many easily available documents and quotes from ParkerVision to prove this. Here are a few:
Doug Makishima, Director of Marketing and Business Development -- Cellular Industry, commented, "The D2D architecture achieves the highest linearity per milliwatt of power consumed of any radio technology of which we are aware, and does this in a very cost-effective manner. The local oscillator in a D2D-based implementation will typically operate at one third or less of the RF carrier frequency. Since D2D uses a subharmonic clock, implementations do not require synthesizers operating at or near the RF frequency as with traditional radio architectures. This provides lower power, higher performance solutions that effectively reduce noise and design issues that are inherent in traditional or other direct conversion designs which require the use of local oscillators operating at or near the RF frequency. This is one of the reasons that our technology lends itself to full integration in standard CMOS and allows D2D-based radio hardware to take full advantage of Moore's Law regarding semiconductors."
“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.”
"The D2D circuit architecture uses sub-harmonic principles to reduce both the on-channel re-radiation and circuit power requirements without sacrificing low path loss or noise figure."
Qualcomm does *not* use a sub-harmonic clock, so this is a key point. There is very clear evidence that ParkerVision got patents issued based on the “novelty” of strictly sub-harmonic mixer clocks, but is now trying to enlarge the claims (via claim construction) to include clocks of the same frequency as the carrier (N=1). Indeed ParkerVision managed to convince the judge to include non-sub-harmonic clocks in his Markman ruling. The problem with PRKR’s Markman “win” is that there is extensive prior art which invalidates *all* of the ParkerVision claims for non-sub-harmonic mixer clocks (I haven’t found prior art for strictly sub-harmonic passive mixers, but I haven’t looked extensively.)
This distinction makes much of the Qualcomm documents from 1999 make much more sense. ParkerVision claimed that using D2D, using sub-harmonic mixer clocks, saved significant power, and eased other RF problems. Before testing the ParkerVision design, Qualcomm apparently agreed that, if the claims were true, that they were interesting in licensing the D2D receiver design. After extensive testing showed that, in fact, sub-harmonic mixers did not work well, Qualcomm terminated further discussions.
Twelve years later ParkerVision is now trying to change the meaning of D2D so that they can claim infringement, but their own documents and quotes will easily show these claims to be specious. In context, the quotes from Qualcomm’s emails and other documents show Qualcomm to be the innocent party, who negotiated in good faith, and who clearly did not “steal” any technology from ParkerVision. I suggest re-reading the excerpts from Qualcomm documents cited by ParkerVision (and longs on this board) in light of what Qualcomm was told about D2D in 1999 – i.e. that D2D a strictly sub-harmonic mixer.