Low-power wireless solutions such as Bluetooth 5
Improved reception sensitivity and increased connection link budget
Reduced the number of retransmissions due to error packages


On the 19th, Nordic Semiconductor released the nRF21540, the first RF Front End Module (FEM) with a built-in Power Amplifier (PA) and Low Noise Amplifier (LNA).

The nRF21540 FEM was developed to complement Nordic’s nRF52 and nRF53 series multiprotocol SoCs. The PA provides adjustable TX power up to +21dBm, and the LNA supports +13dB RX gain.

The LNA has a low noise figure of only 2.5dB, which increases the reception sensitivity of Nordic’s Bluetooth 5, Bluetooth LE (Low Energy), Thread, Zigbee, and 2.4GHz RF low-power wireless solutions.

When the nRF21540 FEM is used with the nRF52840 SoC running Bluetooth LE at 1 Mbps, the reception sensitivity can be increased by up to 5 dBm. As the output power increases, the connection link budget increases by up to 18 dBm. For other devices with built-in TX power of less than +8dBm, performance can be improved even more significantly.

Increasing the connection link budget significantly improves reach and reduces the number of retransmissions caused by error packets. Therefore, using the nRF21540 can provide useful additional features for any application requiring enhanced reach or robust coverage. It is particularly suitable for asset tracking, audio, smart home, and industrial applications.

The nRF21540 FEM is a plug-and-play complementary device for use with Nordic's short-range wireless SoCs. The nRF21540 connects to the antenna outputs of Nordic SoCs and features two additional antenna ports to enable antenna diversity. The device's gain control, antenna switching, and power modes can be controlled using GPIO, SPI, or both ports.

The TX power of the nRF21540 is highly adjustable, and the output power can be set in small increments up to 21 dBm. This allows the output power to be designed within an acceptable range of 1 dBm for all regions and operating conditions.

Power settings can be dynamically controlled by the SoC by considering current connection requirements even during use. For example, power requirements for a specific connection can be determined by monitoring RSSI (Received Signal Strength Indication) and other parameters, and power consumption can be managed by raising or lowering the TX power. It can respond to all temperature-related changes, allowing output power to be stabilized at the desired level.

The nRF21540 operates in a supply voltage range of 1.7 to 3.6 V and provides power performance of 115 mA in TX, 4.1 mA in RX mode, and 30 nA in power off mode when tuned to +20 dBm. This device has obtained operating temperature certification in the range of –40° to 105°C and can complement Nordic’s high-temperature supporting nRF52833 and nRF5340 in applications such as professional lighting.

This chip is supplied in a 4x4mm QFN16 package. To complement the launch of the nRF21540 IC, Nordic provides a development board that allows evaluating the performance of RF front-end modules using laboratory equipment or evaluating real-world application performance based on nRF52 series devices.

Kjetil Holstad, Director of Product Management at Nordic Semiconductor, stated, “For many applications, external RF FEMs are used to improve range,” but added, “FEMs must not compromise other wireless performance functions or significantly impact battery life.”