Nordic Semi nRF21540 RF front end module Extends the Range of nRF52/nRF53 Bluetooth SoC’s

A little while ago, we wrote about RFCat N32 board integrating Meshtek-H52 module with nRF52832 2.4GHz multi-protocol SoC and a Skyworks power amplifier increasing power by up to 30 times to extend the wireless range to up to 200 meters.

It turns out Nordic Semi outed its own range extender module late last year with nRF21540 RF front end module (FEM) that integrates a power amplifier (PA) and low noise amplifier (LNA) optimized to boost the link budget of the nRF52 and nRF53 multi-protocol wireless SoCs.

nRF21540 key features and specifications:

• Supported wireless standards
  • Bluetooth Low Energy (incl. Bluetooth mesh)
  • Thread and Zigbee (802.15.4)
  • Proprietary 2.4 GHz
• Output Power – Adjustable in small increments up to +21 dBm
• Receive Gain – +13 dB with 2.5 dB noise figure
• Antennas – 2x antenna ports for antenna diversity
• Host Interface – I/Os, SPI, or a combination
• Supply Voltage – 1.7 V to 3.6V
• Current consumption
  • Tx tuned to +20 dBm: 115 mA
  • Rx: 4.1 mA
  • Power down mode: 30 nA
• Temperature Range – -40°C to +105°C
• Package – QFN16  4×4 mm

When nRF21540 is combined with an nRF52 or nRF53 SoCs, Bluetooth LE (1Mbps) gets up to 16 times range increase, and -100 dBm RX sensitivity.

Typical applications would include Asset tracking and RTLS (real-time location system), professional lighting, smart Home, toys, audio devices, and industrial equipment.

nRF21540 development kit

The company also provides a full-featured development kit with the following features:

• WiSoC – Nordic Semi nRF52840 Arm Cortex-M4F SoC with Bluetooth LE, 802.15.4, 2.4 GHz protocol support
• Range Extender – nRF21540 RF front end module
• Antennas – 2x 2.4 GHz antennas for antenna diversity, NFC antenna connector
• USB – 1x Micro USB connected to nRF52840 SoC, 1x Micro USB for program/debug and power
• Expansion – Arduino Uno Rev3 compatible headers
• Debugging
  • Segger J-Link OB programming/debugging via Micro USB port
  • 2x SWF RF ports for direct RF measurements
• Misc – 4x user-programmable buttons and LEDs
• Power
  • 5V via Micro USB “programming” port
  • Coin-cell battery holder
  • Pins for current consumption measurements

The board shares many of the same features as the original nRF52840 DK, meaning software support is basically identical.

nRF21540 Evaluation Kit/Shield

The company also provides nRF21540 evaluation kit that is meant to connect the RF FEM to lab equipment or other radios via an SMA connector. The nRF21540’s gain control, antenna switching, and modes are controlled via GPIO or SPI or a combination of both via the Arduino Uno Rev3 compatible headers fitted to the shield. Two extra SMA connectors are hooked to the dual antenna ports from the RF FEM to monitor the performance of the RF FEM using any equipment desired.

Pricing & Availability

The product page on Nordic Semi website has a link to request samples, but no price is specified. The nRF21540 PA/LNA module is however listed on Mouser for $2.26 (sample price) or $1.49 per unit in quantities of 250 or greater. I was unable to find pricing for the development and evaluation kits.

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