Nordic Semiconductor samples nRF21540 RF Front End Module

By Tiera Oliver

Associate Editor

Embedded Computing Design

January 28, 2020


Nordic Semiconductor samples nRF21540 RF Front End Module

A 'plug and play' range extender for its short-range wireless portfolio.

Nordic Semiconductor announces the nRF21540 RF Front End Module (FEM), a power amplifier/low noise amplifier (PA/LNA) product. The nRF21540 has been developed to complement Nordic's nRF52 and nRF53 Series multiprotocol Systems-on-Chip (SoCs).

The RF FEM's PA offers an adjustable TX power boost up to +21 dBm, with the LNA providing +13 dB RX gain. The LNA's low noise figure (NF) of 2.5 dB also offers increased RX sensitivity for Nordic's Bluetooth 5/Bluetooth Low Energy (Bluetooth LE), Thread, Zigbee, and 2.4GHz RF low power wireless solutions. When combined with an nRF52840 SoC running Bluetooth LE at 1 Mbps, for example, the nRF21540 improves the RX sensitivity by 5 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 a longer range and helps lower the number of retransmissions due to corrupt packages. The nRF21540 can be used for applications that may require increased range or robust coverage. Some example applications are asset tracking, audio, smart home, or industrial use cases.

The nRF21540 is a 'plug and play' complementary device when used with Nordic's short-range wireless SoCs. The nRF21540 connects to the SoC's antenna output and features two additional antenna ports to enable antenna diversity features. The device's gain control, antenna switching, and power modes are controlled via GPIO or SPI or a combination of both. While the device can be used with other radios, its easy use with Nordic SoCs is further enhanced as driver support will be rolled out as part of future releases of Nordic's nRF5 SDK, nRF5 SDK for Thread and Zigbee, and the nRF Connect SDK.

The nRF21540's TX power is adjustable and output power can be set up to 21 dBm in small increments. This ensures designs can run with output power within 1 dBm of the allowable range across all regions and operating conditions. During use the power setting can be controlled by the SoC to take into account the requirements of the current connection. For example, received signal strength indication (RSSI) and other parameters can be monitored to determine power requirements for a particular connection and TX power raised or lowered to manage power consumption. Any variations due to temperature can be counteracted so the output power is stable at the desired level.

Operating across a 1.7 to 3.6 V supply range, the nRF21540 offers competitive power numbers of 115 mA at TX tuned to +20 dBm, 4.1 mA in RX mode, and 30 nA in power down mode. The device is qualified across a -40 to 105°C range allowing it to complement Nordic's high-temperature rated nRF52833 and nRF5340 in applications such as professional lighting. The chip is supplied in a 4x4 mm QFN16 package, and complementing the release of the nRF21540 IC itself, 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 Series device.

The nRF21540 RF FEM is now sampling to lead customers. For more information, please visit:

Tiera Oliver, Associate Editor for Embedded Computing Design, is responsible for web content edits, product news, and constructing stories. She also assists with newsletter updates as well as contributing and editing content for ECD podcasts and the ECD YouTube channel. Before working at ECD, Tiera graduated from Northern Arizona University where she received her B.S. in journalism and political science and worked as a news reporter for the university’s student led newspaper, The Lumberjack.

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