Ultra-miniature matched baluns with an integrated harmonic filter for long-range wireless STM32WL microcontrollers


Optimize RF performance and design resources thanks to a unique companion chip solution.

Based on ST's IPD technology on non-conductive glass substrate, our integrated baluns embed impedance matching network and transmit harmonic filters customized to maximize the RF performance of STM32WL sub-GHz wireless microcontrollers.

As no external components are required for matching and for harmonic filtering, the BOM count is reduced by 80%, from 5 components to one single component. In addition, their integrated harmonic filters make it easy to comply with major EMC regulations: CCC, FCC, ETSI, and ARIB.

Designed specifically as a companion chip for sub-GHz STM32WL SoCs, two BALFHB-WL (864 to 928 MHz) and BALFLB-WL (470 to 530 MHz) series are available in order to match the various configurations of power, PCB layers and STM32WL packages. And despite this high flexibility, all our ultra-miniature baluns have the same pin-out and size.

stm32wl baluns
stm32wl baluns 2

Key features

  • Monolithic RF solution with a matching network, balun, and harmonics filter
  • Optimum impedance matched to STM32WL SoCs
  • Low temperature variation compared with discrete solutions
  • Reduced PCB space
  • Low profile
  • Reduced RF BOM component count
  • High filtering performance to pass FCC and ETSI requirements
  • Simplifies matching and filtering network complexity
10 year longevity

Application examples

logistics and asset tracking Logistics and asset tracking
smart agriculture Smart Agriculture
smart meter Industrial IoT
idea bulb Smart cities & buildings
gas sensor Utilities

Recommended resources


STM32WL System-On-Chip integrates both an ultra-low-power, general-purpose microcontroller and a sub-GHz radio on the same chip.

reference design

Available to help application engineers obtain the best RF performance and pass certification tests, these reference designs can be manufactured from downloadable files. A complete application can be prototyped thanks to the access to all GPIOs.

Designed to work with the STM32WL Nucleo-64 development board (NUCLEO-WL55JC), a comprehensive software HAL library and example code is available as well as firmware source code distributed under the 3-Clause BSD License.

Suitable for rapid prototyping of end nodes based on LoRaWAN®, Sigfox™, WM-Bus, and many other proprietary protocols.

pdf baluns

Tuned for high RF integration, ST’s RF IPD baluns provide improved system performances while simplifying RFIC to antenna matching network complexity.

pdf stm32wl

A pioneer in sub-GHz wireless connectivity, the STM32WL series is easy-to-use, reliable and tailored for a wide range of RF applications.

pdf stm32wl portfolio

Discover the advantages and benefits of the only LoRa-enabled SoC in the world and its comprehensive development ecosystem

Anicet GIAIMO, Product Marketing Manager for wireless MCUs at ST, tells you about use cases of the STM32WL, the world's first LoRa-enabled SoC.

Anicet describes how our development ecosystem, including new reference designs, hardware tools and software packages, helps engineers remove roadblocks, simplify design stages, and accelerate their development. A proven solution, the STM32WL lets users create IoT devices that are extremely compact, energy efficient, and reliable, extending the IoT's reach and accelerating digital transformation.

pdf integrated passive devices ipd for rf applications

This presentation highlights the Integrated Passive Devices technology and its benefits for RF Microcontroller companion chips such as baluns and matched filters.