various application domains. However, the deployment of massive numbers of interconnected sensors requires ultralow power solutions enabling multi-year battery life. To increase the autonomy of sensors, imec develops ultra-low power wireless technology for IoT applications, such as next-generation Bluetooth low energy and IEEE 802.15.4.

imec’s novel receiver concept features sub-1-nJ/bit energy efficiency and low supply voltage operation at 0.85 V while maintaining similar receiver sensitivity as best-in-class products. The receiver employs digital phase-tracking to directly translate the RF input to demodulated digital data. A digitally-controlled oscillator (DCO) is used instead of a power-hungry phase locked loop (PLL). The receiver, implemented in 40-nm CMOS, is only 0.3 mm², which is at least 3x smaller compared with the state-of-the-art. Due to this small size it can be manufactured at strongly reduced cost.

Especially in wearable or implantable devices, the antenna impedance can dynamically change due to variations in a device’s position or surroundings. This can deteriorate the radio’s performance and degrade battery lifetime. imec demonstrated a fully integrated, sub-mW impedance-detection technique for ultralow-power radios, enabling tunable matching between the antenna and the radio front-end. This technique can be implemented in an adaptive radio front-end to further improve receiver sensitivity and transmitter efficiency in the presence of antenna impedance variations.

“This innovative receiver concept will not only serve the new Bluetooth 5 devices, but provides our industrial partners a long-term competitive advantage for multiple new generations of Bluetooth and 802.15.4 radios, still to come.”, said Kathleen Philips, program director, Perceptive Systems at imec/Holst Centre. “This great achievement is a confirmation of our continuous efforts to push the technology limits toward ever higher performance, lower power consumption, and smaller form factor, which are essential features for internet-of-things radio solutions.”

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