There is a high degree of interest in using the spectrum around 60GHz for very high speed wireless communications, and even an IEEE standards project targeted at this. With this ‘millimeter wave’ spectrum license-exempt in the US and plentiful in supply elsewhere, there are clear applications in home media networks and backhaul. But to be commercially viable in mass markets, it is essential that the chips can be fabricated in low cost CMOS, a feat that has not been achieved outside the labs, with gallium arsenide (GaAs) the main material in use. Now Toshiba, which is one of the vendors pushing a 60GHz standard called WirelessHD for in-home systems, has made a CMOS breakthrough, and claims it will dramatically reduce the cost of millimeter wave devices.
The company presented its advance last week at the 2007 Symposia on VLSI Circuits in Kyoto, Japan. Its test chip measures 2.4mm by 1.1 mm, and all required receiver function blocks are integrated, including an antenna, low noise amplifier, mixer and PLL synthesizer, using a 90nm CMOS process. “We integrated a PLL synthesizer on chip and believe that it’s the first chip that operates alone as a receiver,” said Toshiya Mitomo, a researcher at Toshiba Mobile Communication Laboratory. One of the reasons for the expense and bulk of GaAs modules was that they required the antenna and synthesizer to be integrated separately using bonding wire. Toshiba says its advance will reduce fabrication costs to 10% of those of a GaAs alternative. IBM had previously shown a 60GHz chipset implemented in silicon germanium, which is more cost efficient than GaAs but does not have the economies of CMOS.
Its key contribution has been to address the problem that, when CMOS process technology is applied at high frequencies, signals are easily leaked and chip operation can become unpredictable. To address this, Toshiba used a differential structure that is common in cellphones but rare in 60GHz products, and sets up noise and parasitic elements to, in effect, cancel one another out.
Toshiba still needs to create an amplifier before it can commercialize its chip, but it is moving quickly and keeping up the momentum behind 60GHz as a future consumer electronics technology. To date, this spectrum has mainly been used by vendors such as Gigabeam for wireless fiber backhaul and point-to-point links, which take advantage of the very high speeds achieved by the extremely narrow and targeted beams.
But last November, six of the world’s biggest consumer electronics companies – Sony, Panasonic, Samsung, Toshiba, NEC and LG Electronics – turned the short range connectivity world on its head, forming the WirelessHD (WiHD) special interest group, which will settle on license-free 60GHz spectrum for connecting entertainment devices in the home (see Wireless Watch November 6 2006). This could be seen as a blow to the efforts of the PC/cellphone community to promote UltraWideBand as the fast, low power wireless network of choice for the digital home, although eventually, an integrated platform combining UWB, 60GHz, Wi-Fi and Bluetooth could also be on the cards.
In May, the supporters’ group submitted the newly finished standard to the IEEE for consideration for its proposed 60GHz platform, 802.15.3c. Although Sony and Toshiba are widely cited as lead creators of the specification, much of it was based on the work already done by 60GHz specialist SiBeam.
However, WirelessHD will face a major challenge in the IEEE from another Japanese dominated group called CoMPA (Consortium of Millimeter Wave Practical Applications), which also submitted its 60GHz proposals in May and which claims to have the greatest market weight behind it, with 20 members, nearly all from Japan (some members belong to both, notably Sony and NEC). The line-up reflects that country’s determination to be in the forefront of next generation wireless standards.
The CoMPA technology can reach a peak of 4.8Gbps over 10 meters in a frequency band ranging over 2,080MHz per channel. The companies expect to prototype a system, with or without IEEE acceptance, by the end of this year, targeting applications such as home high definition video transmission and video downloads from kiosks. The IEEE 802.15.3c task group has accepted 16 proposals for its standard, heralding a likely new political battle like the ones that delayed 802.11n and derailed the UWB-based WPan activities.
By talking up WirelessHD and CoMPA in advance, the CE giants are no doubt aiming to remind the IEEE of the situation it faced when stalemate was reached in UWB, prompting Intel and Texas Instruments to take their product for ratification elsewhere rather than lose the race. Toshiba and co, which are used to the more collaborative and streamlined standards processes of the CE sector, will likely put pressure on the IEEE to accept their offering almost as a fait accompli, or the threat is clear – we would like to do this under IEEE auspices, but we will put commercial systems into the field next year anyway, and the market can decide. The crunch will come if the two Japan-led groups fail to come to rapprochement, potentially stalemating the process and casting even more doubts on the credibility of the IEEE in mass market standards setting.
The full 20-strong line-up of CoMPA is heavily Japanese in flavor,. The members are NICT, Sony, Matsushita, Tensorcom, NTT, Tohoku University, Fujitsu, Mitsubishi, Oki Electric, Maspro Denkoh, ATR , NEC, Kyocera, Tokyo Institute of Technology, Eudyna Devices, Japan Radio, EMMEX, Taiyo Yuden, Ricoh and Toyo System Engineering.
Other technologies proposed to the IEEE taskgroup include one from Philips Electronics, which has not been detailed as yet. One of the key vote casters will be Intel, which beyond calling for 802.15.3c to be OFDM-based like WiMedia and 802.11n, has not submitted a proposal nor thrown its weight behind any of the groups. Given Intel’s market weight as a chipmaker, its ambitions in the CE world, and its power and expertise in working the IEEE processes, its support will be keenly sought by all parties.
One route that Intel is likely to favour in future is convergence between different WPan technologies, particularly a combination of UWB with 60GHz spectrum. However, the giant has been ambivalent about 60GHz, despite doing R&D projects of its own on CMOS implementations. Stephen Wood, head of the WiMedia Alliance and an Intel employee, said last fall: “The regulations for 60GHz radios are not all in place, and the standards aren’t ready yet.” He claims the Alliance had studied 60GHz and concluded it would not be market ready for at least two years. The need for multiple sources of chips and interoperability testing would stretch time to market still further, he said.