Toshiba’s Advanced Bluetooth^® Low Energy SoC Delivers Long-distance Communication in a Compact Module

TOKYO—The world is leaving wires behind, and Toshiba Group is helping. Bluetooth^® has established itself as the de facto standard for connectivity in applications as diverse as drones, headphones and wireless audio, wearable tech and smart tags in IoT networks. Toshiba Corporation and Toshiba Electronic Devices & Storage Corporation (“Toshiba Electronic Devices & Storage”) have developed a Bluetooth Version 5.0 compliant System-on-Chip that realizes the industry’s most compact and powerful ^[1] module.

The Bluetooth^® Version 5.0 standard delivers double the transmissions speed (2M PHY) and extends the communication range (Coded PHY). Toshiba and Toshiba Electronic Devices & Storage have taken that even further, with an SoC that can communicate over distances as long as 600m.

In Bluetooth^® SoC, communication range is determined by the difference between transmission power and the sensitivity of the receiver, known as the link budget. The new Toshiba SoC has a link budget of 113dB, the largest yet achieved ^[1], and the key to its communication performance. Toshiba has also minimized module size by reducing the off-chip component count to about half ^[2] of other products that realize a similar range.

Further progress in wireless connectivity can only be achieved by longer range communications and smaller modules. Developers of Bluetooth^® SoC have two routes to this: either add power circuits and components to raise power-supply voltage or decrease load impedance ^[3]. But this comes with a trade-off. The former increases module size, the latter limits range.

Toshiba and Toshiba Electronic Devices & Storage have developed an impedance matching technology that minimizes the trade-off.

Current technologies improve receiver sensitivity by reducing impedance in the transmitter at the image noise frequency, causing the image noise flow to the transmitter side. However, the increased output power of the SoC transmitter prevents use of this technique. Toshiba and Toshiba Electronic Devices & Storage mounted noise rejection filters on the receiver side in an impedance circuit built around a transformer.

Usually, the inductor used in a noise rejection filter degrades receiver sensitivity by parasitic resistance. However a transformer can have thicker coils, and requires less winding than an inductor, improving receiver sensitivity. As both an inductor and a transformer must be physically isolated from other circuits, the transformer size is only 26% larger than the inductor, and the overall size of the transceiver and the overall size of the rejection filter with the transformer is only 1% bigger than with an inductor.

This advance realizes long range communication and a compact module at the same time.

Toshiba and Toshiba Electronic Devices & Storage presented the new SoC technology at ESSCIRC2018, the international conference on semiconductor devices held in Dresden, Germany on September 6. This month, Toshiba Electronic Devices & Storage will start mass production of the Bluetooth^® low energy SoCs that also integrates new technologies to suppress harmonic emission and improve power amplifier efficiency.

*Bluetooth^® is a registered trademark of Bluetooth SIG, Inc.  

*Other company names, product names, and service names may be trademarks of their respective companies.