nRF21540RF FEM

RF front-end module (FEM) for Bluetooth® Low Energy, Bluetooth® mesh, Thread and Zigbee and 2.4 GHz proprietary range extension

The nRF21540 is a ‘plug and play’ range extender offering enhanced link robustness with an integrated power amplifier (PA) and low noise amplifier (LNA) for use in our low power short-range wireless solutions. It is a complementary device optimized to boost the link budget of the nRF52 and nRF53 Series advanced multiprotocol wireless SoCs. When combined with an nRF52 or nRF53 Series SoC, the nRF21540 RF FEM’s +20 dBm TX output power and 13 dB RX gain ensure a superior link budget for between 16 and 20 dB improvement. This equates to a 6.3 to 10 times theoretical range improvement.

The nRF21540’s TX power is dynamically adjustable and output power can be set up to +21 dBm in small increments. This ensures that designs can run with output power within 1 dBm of the allowable range across all regions and operating conditions. The LNA has a low noise figure of 2.7 dB that ensures improved RX sensitivity.

The nRF21540 complementary device connects to an SoC’s antenna output. It includes two additional antenna ports for antenna diversity support. The TX output power, TX gain control and antenna switching can be controlled via SPI, GPIO pins or a combination of both.

The nRF21540 offers competitive numbers of 110 mA at +20 dBm TX output power, 38 mA at +10 dBm TX output power, 2.9 mA in RX and 45 nA in power down mode. The extended operating temperature range is qualified from -40 °C to 105 °C, making it an ideal choice for professional lighting along with an nRF52820, nRF52833 or nRF5340 SoCs.

Some of the main applications tailored to the nRF21540 include smart home, asset tracking, audio, as well as industrial applications.

The chip is supplied in a 4x4 QFN16 package and complementing the release of the nRF21540 RF FEM, Nordic offers development boards that enable evaluation of the RF FEM performance using lab equipment, as well as real application performance combined with an nRF52 or nRF53 Series SoC.

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Key features

Supports Bluetooth® Low Energy, Bluetooth® mesh, Thread and Zigbee (802.15.4) and 2.4 GHz proprietary protocols

Tunable output power in small increments up to +21 dBm

13 dB RX gain with 2.7 dB noise figure

Two antenna ports for antenna diversity

TX gain control via I/Os, SPI, or a combination

-40 °C to 105 °C extended operating temperature range

1.7 to 3.6 V supply range

4x4 mm QFN16 package

110 mA at +20 dBm TX output power

38 mA at +10 dBm TX output power

2.9 mA in RX

45 nA in power down mode

Between 6.3 and 10x range extension when combined with an nRF52 or nRF53 Series SoC


nRF21540 development kit

The nRF21540 development kit (DK) contains the nRF21540 RF FEM and has two antennas with SWF ports for direct RF measurements. The dual antennas can be used in an antenna diversity scenario with for instance Thread or Zigbee (802.15.4) protocols to reduce multipath fading effects. The RF FEM is connected to and controlled by the nRF52840, an advanced multiprotocol Bluetooth® 5.2 SoC that supports Bluetooth® LE, mesh networking protocols such as Bluetooth® mesh, Thread and Zigbee, as well as 2.4 GHz proprietary protocols.

Sharing many similarities with the nRF52840 DK, the nRF21540 DK contains an onboard Segger J-LINK debugger accessible through USB, user-programmable LEDs and buttons, an NFC antenna connector and current measurement pins. It is the perfect tool to enable real application performance testing with the extended range offered by the nRF21540 RF FEM.

nRF21540 evaluation kit

On the nRF21540 evaluation kit (EK) the nRF21540 RF FEM connects to lab equipment or radio via an SMA connector. The nRF21540's gain control, antenna switching, and modes are controlled via GPIO or SPI or a combination of both, accessible through the Arduino Uno Rev3 compatible headers. The nRF21540 EK also features two additional SMA connectors hooked to the dual antenna ports, to monitor the performance of the RF FEM using any equipment desired.

nRF21540 compatible SoCs