Nordic Semiconductor today announces the launch of the nRF21540™ Development Bundle (DB) – design tools for verification and testing of applications that require the range extension or link budget improvements provided by the nRF21540 RF Front-End Module (FEM). The nRF21540 DB comprises the nRF21540 Development Kit (DK) and the nRF21540 Evaluation Kit (EK). 

The previously released nRF21540 RF FEM is a power amplifier/low noise amplifier (PA/LNA) product. The RF FEM perfectly complements Nordic’s nRF52 and nRF53 Series multiprotocol Systems-on-Chip (SoCs). The product is targeted at applications that benefit from increased range when employing 2.4 GHz technology. Examples include industrial automation, lighting mesh networks and other home automation, asset tracking and wireless audio. In addition to increasing the range of the wireless transmission, the nRF21540 RF FEM enhances the robustness of the wireless link – reducing radio packet losses and in turn the requirement for retransmissions. Fewer lost packets result in lower link latency, and fewer retransmissions boosts the wireless link’s throughput and reduces power consumption. The RF FEM also supports antenna diversity which brings further improvements to link robustness for static installations. 

Enhanced connection link budget

The nRF21540 RF FEM’s PA offers a highly adjustable TX power boost up to +21 dBm, enabling a single product to meet the different maximum transmission power regulations across all regions of the globe. The IC’s LNA provides +13 dB RX gain. The LNA’s low noise figure (NF) of only 2.7 dB also ensures increased RX sensitivity for Nordic’s SoCs. When combined with an nRF52840 SoC running Bluetooth® Low Energy (Bluetooth LE) at 1 Mbps, for example, the nRF21540 improves the SoC’s RX sensitivity by 5 dBm to -100 dBm. Coupled with the increased output power, the connection link budget is raised by 18 dBm. For other devices with less than +8 dBm TX power on-chip, the improvements are even larger. The resulting increase in connection link budget offers range increases of between 6 to 10x compared with similar applications without the RF FEM.

The nRF21540 DK is the ideal tool for application performance testing of designs taking advantage of the extended range offered by the nRF21540 RF FEM. Based on Nordic’s nRF52840 DK (a mature DK for development work with the nRF52840 advanced multiprotocol SoC), the nRF21540 DK incorporates the nRF21540 RF FEM and has two chip antennas and ports for antenna diversity and additional SWF connectors for making direct RF measurements. The DK’s RF FEM is connected to and controlled by the onboard nRF52840 SoC. (The SoC supports all Bluetooth 5.3 features, as well as Bluetooth mesh, Thread, Zigbee, and 2.4 GHz proprietary protocols.) The nRF21540 DK includes an onboard Segger J-LINK debugger accessible through USB, four user-programmable LEDs and four buttons, an NFC-A tag antenna connector, and current measurement pins.

Simplified radio testing

The nRF21540 EK is a shield incorporating the nRF21540 RF FEM and can be used for easy radio testing and development. The EK can be connected directly to an nRF52 or nRF53 Series SoC antenna output or to any of the Nordic SoC DKs via their Arduino Uno Rev 3 header pins. The EK’s nRF21540’s gain control, antenna switching, and operational modes are controlled via GPIO or SPI or a combination of both, accessible through the Arduino Uno Rev3 compatible headers. The EK features an SMA connector for connecting a radio or lab equipment and two additional SMA connectors attached to RF FEM’s dual antenna ports for the connection of lab equipment. 

The nRF Connect SDK (Software Development Kit) is recommended for use with the nRF21540 RF FEM. The SDK includes support for the nRF21540 DK and EK via the nrfxlib Multi-Protocol Service Layer (MPSL) library. The library provides support for the GPIO switching mode. While the nRF21540 RF FEM can be used with other devices, its ease-of-use with Nordic SoCs is enhanced with this driver support.

“While the nRF21540 RF FEM will almost certainly extend the range and increase the link budget of any compatible 2.4 GHz radios such as Nordic’s nRF52 and nRF53 Series SoCs, it can be difficult for a developer to work out how to ensure their design gains maximum benefit from the product,” says Paal Kastnes, Technical Marketing Manager with Nordic Semiconductor. “The nRF21540 DB now makes it very easy for developers to experiment with the FEM such that they can become familiar with the capabilities and configuration of the product and use it to its best advantage in their end-product.”