Bluetooth Low-Energy transceiver slashes consumption by over half

Bluetooth Low-Energy transceiver slashes consumption by over half

Technology News |
By Christoph Hammerschmidt

The breakthrough set to accelerate widespread adoption of Internet of Things (IoT) applications was developed by a group of researchers led by Kenichi Okada of Tokyo Institute of Technology, Japan.

When transmitting, the transceiver consumes 2.9 milliwatts (mW) and when receiving, it consumes just 2.3 mW. Given that minimizing power consumption is a requirement for the oncoming IoT era, these figures are remarkable, as they represent less than half the power consumed by previous transceivers (see the table below).


  Tokyo Tech
ISSCC 2018
ISSCC 2015
ISSCC 2015
Texas Instruments
Transmitter 2.9 7.7 10.1 63 32
Receiver 2.3 6.3 11.2 58 39

Table: A performance comparison of BLE transceivers. Tokyo Tech’s BLE transceiver achieves a dramatic reduction in power consumption – down to less than half of those previously reported. All figures are in milliwatts (mW).


The BLE transceiver has excellent receiver sensitivity – in their study the reseachers achieved an impressive -94 decibels relative to 1 milliwatt (dBm). Thje receiver also exhibits high interference tolerance, while also realizing the lowest power consumption.

The transmitter employs an all-digital phase-locked loop (ADPLL), an attractive building block for BLE, as it is less susceptible to noise compared to its analog counterpart. The transceiver was designed in a 65-nanometer CMOS process.

In another study focusing on ADPLL, the researchers achieved a figure of merit4 (FoM) of -246 dB, one of the best obtained so far. The FoM is an important metric for evaluating the trade-off between performance and power consumption. The FoM evaluates the trade-off between jitter (related to noise in wireless communication) and power consumption. Reducing jitter is desirable for improving the quality of communication, but this requires more energy, so there is a trade-off between performance and power consumption. In general, the lower the FoM, the better.

The above results arose from a project supported by Japan’s New Energy and Industrial Technology Development Organization (NEDO).

Already embedded in millions of Apple and Android devices, BLE is the most used short-range wireless technology aimed at low-power and low-cost connectivity.

Low-energy solutions are in demand not only for smartphones and watches, but also for emerging applications in the medical and healthcare fields, factories and public infrastructure such as roads, bridges and tunnels. However, to make the IoT work practically, pwer consumnption is a huge constraint.

“Our research grew out of this need for connectivity,” explains Okada. “In an IoT world, trillions of devices will be used. To extend battery life and aim for maintenance-free operations, reducing power consumption is vital.”

In future, Okada says: “The PLL could operate on just 0.65 mW, and studies are underway to reduce our transceiver’s power consumption even further.”

The team is presenting their findings at the 2018 International Solid-State Circuits Conference (ISSCC) with two papers.



Title: A 0.98mW Fractional-N ADPLL Using 10b Isolated Constant-Slope DTC with FOM of -246dB for IoT Applications in 65nm CMOS
Authors: Hanli Liu, Dexian Tang, Zheng Sun, Wei Deng, Huy Cu Ngo, Kenichi Okada, Akira Matsuzawa
Affiliation: Tokyo Institute of Technology, Tokyo, Japan

Title: An ADPLL-Centric Bluetooth Low-Energy Transceiver with 2.3mW Interference-Tolerant Hybrid-Loop Receiver and 2.9mW Single-Point Polar Transmitter in 65nm CMOS
Authors: Hanli Liu, Zheng Sun, Dexian Tang, Hongye Huang, Tohru Kaneko, Wei Deng, Rui Wu, Kenichi Okada, Akira Matsuzawa
Affiliation: Tokyo Institute of Technology, Tokyo, Japan

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