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Sensors/MEMS??

Fujitsu-Imec partnership yields wireless transceiver tech

Posted: 18 Feb 2014 ?? ?Print Version ?Bookmark and Share

Keywords:wireless transceiver? Fujitsu? imec? BAN?

The 4.5Mbit/s high-speed mode optimises the frequency characteristics of the low-pass filter and AD converter through digital circuits. In the 11.7kbit/s low-speed, low-power mode, the low-noise amplifier operates at lower power, which degrades its sensitivity, but digital processes compensate for this.

The companies used a transmitting mixer in the transmitter to make it easier to implement high-speed mode, but mixers and their driver circuitry are known to greatly increase power demands. So a combination of the following techniques was employed:

  • Rather than using a transmitting mixer, the circuitry was given a digital three-point modulation scheme in which a PLL that generates the wireless signal from the digital circuit takes high-frequency and low-frequency signals as input, and, similarly, the amplified transmit signal is input to the power amplifier.
  • To implement the high-speed mode using digital three-point modulation, a dual-varactor circuit technology was developed, increasing the variation in the varactor's capacitance at the VCO, which takes the high-frequency modulated signal as input.
  • For low-speed/low-power mode, a low-power technology was developed to reduce the VCO modulation circuit's baseline current by 90 per cent while still allowing modulation.
  • This transceiver circuit for healthcare applications has potential applications beyond patient monitoring, and could be used as a sensing front-end interface for medical-device management. In both applications, the lifespan of the batteries used in the sensor nodes will be greatly extended, relieving the burden on patients and making operations more efficient for medical practitioners.

    Fujitsu Laboratories plans to extend its application beyond medicine and healthcare, applying it as a fundamental network front-end technology for use in such areas as agriculture and livestock management, monitoring of societal infrastructure and structures, factory monitoring, and environmental monitoring.


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