Panasonic holds 26 Japanese patents and 19 overseas patents (including pending) related to this technology.
Development of this technology was supported in part by the "Research and Development for Expansion of Radio Spectrum (News - Alert) Resources" program of The Ministry of Internal Affairs and Communications, Japan. A field test starts today at The ICT Incubation Laboratory in Research Center for Advanced Science and Technology, the University of Tokyo.
More on the Technology
1. Multi-mode technology that reduces both power consumption and memory capacity requirement based on frequency detection by hardware and unified control by common software for multiple wireless operation modes.
In wireless sensor networks, FSK modulation is normally used. Conventional FSK demodulators, such as Arctan demodulators, detect the operation frequency by monitoring received signals in time domain and then demodulate based on the detected frequency. In order to receive multi-mode signals of different frequencies or based on different standards, a receiver needs to eliminate noise in accordance with bandwidth of each mode, thus a dedicated wireless LSI is required for each wireless mode.
Panasonic developed technologies to detect all frequency components simultaneously within multiple modes by employing Short-time DFT, which can also determine the data rate with respect to each mode by hardware and then demodulate by achieving an optimum control to the data rate. In addition, instead of switching among multiple software control modules each corresponding to one transfer rate, a unified software module for all modes is newly implemented. These technologies enable a single LSI to support multiple wireless modes.
2. Receiver power reducing technology that enables 20-year battery operation while supporting multiple wireless modes, which is achieved by intelligently controlling voltage supplies to minimize circuit current, and by generating high rate internal clocks from low rate clocks.
In conventional wireless receivers, a constant voltage is used for every circuit to guarantee a whole stable operation regardless of operation frequencies or temperatures. However, to maintain such a constant voltage a strong enough supply voltage has to be supplied all the time. This causes waste when a lower power supply is sufficient.
Panasonic developed an intelligent power supply technology which controls a voltage dynamically for a circuit according to its frequency, temperature and process variations. The dynamic control minimizes current consumption of a circuit. As an example, for the high frequency oscillator circuit which consumes the most of current, it reduces by 70% compared to our previous design.
Also a high SNR is required for an analog-to-digital converter (ADC (News - Alert)) to process received signals. Conventionally this is realized by a high rate sampling circuit which picks out pulses from a 100MHz clock. But such a circuit consumes much power.
Panasonic developed a technology to generate high rate sampling pulses from a low rate clock by using its rising edge effectively. Furthermore, Panasonic developed a SAR-ADC which can realize a high SNR equivalent to that generated by a conventional ?S ADC, but with lower power consumption. Compared to our previous design it has been reduced by 60%.
3. Wireless LSI miniaturizing technology which reduces the size of coils in oscillator circuits and eliminates filters used in analog-to-digital converters.
Conventional oscillator circuits require large coils to minimize the increase of circuit current due to transistor performance variations. The newly developed intelligent power supply control technology compensates for the transistor variations and enables use of twice the oscillation frequency. This makes a small-sized oscillator circuit to be realized, which has a smaller coil and a divide-by-two circuit both with low current consumption. In addition, instead of conventional analog-to-digital converters of the ?S ADC that have been necessary to achieve required performance, a SAR-ADC is adopted in the new technology which makes a compact filter-less analog-to-digital converter possible.
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