“World’s Smallest” BLE Module Emerges from Toshiba and Nordic Semi Team-upMay 13, 2021 by Adrian Gibbons
Capitalizing on a 14.1% market growth in the 2020 wearable IoT market, Toshiba and Nordic Semiconductor partner to bring the world’s smallest BLE module.
Toshiba's new Bluetooth module integrates Nordic Semiconductor's nRF52811 SoC. Image used courtesy of Nordic Semiconductor
With team-ups happening all over the electronics industry, it is always interesting to find out why, what, and how each company is trying to accomplish or solve a problem. With this most recent announcement, what can be learned from Nordic Semiconductor and Toshiba teaming up to create this Bluetooth module?
Nordic Semiconductor’s nRF52811 System-on-Chip
The nRF52811 is the 4th member added to Nordic Semiconductor's nRF52 family of system-on-chip (SoC). This SoC is a 64 MHz Arm Cortex M4 based SoC, with numerous digital interfaces including PDM, PWM, UART, SPI, TWI, and a 12-bit ADC interface.
With the nRF52811, Nordic has added direction-finding via Bluetooth. It is the newest feature incorporated into Nordic's low-power SoC devices. Using a 4.6 mA peak in TX (0 dBm), the device is said to use 80% less power than the nRF51 series chips.
New hardware, combined with Nordic Semiconductor's highly configurable S112 SoftDevice Bluetooth stack, means developers can get started on applications quickly.
Toshiba & Nordic Partnering for BLE Wearable Dominance
Nordic Semiconductor is a leader in the field of system-on-chip Bluetooth devices. Nordic, combining expertise in both hardware and software development, offers several families of SoCs with embedded Bluetooth protocols.
The nRF52811 WLCSP package SoC. Image used courtesy of Nordic Semiconductor
Toshiba's new slot antenna on a shielded package (SASP) is only 4 mm (W) x 10 mm (L) x 1 mm (H). This SASP offers a very competitively sized package to house the nRF52811 (a 2.5 mm x 2.5 mm wafer level chip scale package (WLCSP) SoC and associated passives.
A high-level graphic of the applications that require ultra-small connected IoT devices. Image used courtesy of Toshiba
With all of these potential applications, especially those that demand smaller and smaller tech, it is no wonder that Toshiba has been working on what it claims is the smallest Bluetooth Low Energy (BLE) module in the world which uses SASP.
What is a Slot Antenna on Shielded Package?
SASP is a trademark pending technology term used by Toshiba for its new Bluetooth module antenna. Although the information on the proprietary SASP technology is scarce (at the moment), the latest Bluetooth module with SASP appears to be a variety of substrate integrated waveguides.
Exploded view of a folded SIW antenna. Image used courtesy of Tomassoni et al and the University of Perugia
Substrate integrated waveguides (SIW) are a newer transmission line (~20 years old) that appear to have been attributed to researcher Ke Wu. The SIWs are based on rectangular microwave waveguide technology. Waveguides contain electromagnetic energy inside a metallic transmission path and only allow propagation at the excitation point (i.e., the slots).
As mentioned, the new Bluetooth module is 4 mm (W) x 10 mm (L) x 1 mm (H) mm in dimension. For comparison, the research from the University of Perugia (above) is a 4.5 GHz SIW measuring ~4.5 mm in length (W undefined).
The fact that wavelength is related linearly to antenna size potentially indicates that the new SASP technology could be a 2.45 GHz SIW antenna.
Overcoming “Keep-out” Zones in Antenna Design
Chip antennas, one of the possible choices for small IoT devices, are subject to relatively large keep-out zones where the designer must avoid specific components and copper.
This limitation forces a minimum size on the associated PCB, which traditional ceramic chip antennas cannot overcome.
According to the Toshiba release on SASP in early January 2021, the SASP technology requires little to no keep-out zone. Further, it says that the slot antenna is formed on the "external shield," which protects it, leading this author to believe that the technology is based on substrate integrated waveguides.
Final Thoughts on the New Toshiba BLE
With mass production of this device coming sometime in 2022, it will be interesting to see how quickly the market could absorb it. At 0.09 g, the new module will be nearly unnoticeable to the user were it added into an article of clothing (a possibility with other built-in sensor technology). Designers interested in medical monitoring and remote connectivity will be sure to check out such a lightweight design option.
Interested in Bluetooth Low Energy? Catch up on some of the other innovations happening with BLE technology down below.