Nine RF integrated passive devices (RF IPDs) from STMicroelectronics combine antenna impedance-matching, balun, and harmonic filter circuity optimised for STM32WL wireless microcontrollers.
The STM32WL MCUs combine application-level processing and wireless communication for smart, connected devices. They integrate an Arm Cortex-M4 microcontroller with a sub-GHz long range radio managed by a Cortex-M0+ core. The radio is LPWAN-compliant, supports multiple modulation schemes, and comes with LoRaWAN and Sigfox stacks included in the STM32CubeWL microcontroller software package.
The RF IPDs are in tiny chip scale packages. They connect the STM32WL microcontroller to its antenna and help maximise the RF performance. By integrating all the components on one die, STMicro said performance is consistent and avoids the process variations that affect conventional matching networks built with discrete components. They also simplify circuit design, save on bill of materials, and permit a smaller form factor, added ST.
The nine RF IPD variants let designers choose the optimum parameters according to the RF frequency range and power, microcontroller package type, and two- or four-layer PCB.
The series comprises the BALFHB-WL-01D3 through BALFHB-WL-06D3 for applications at 868MHz and 915MHz. The BALFLB-WL-07D3, BALFLB-WL-08D3, and BALFLB-WL-09D3 are optimised for 490MHz. Each integrates the complete receive and transmit signal paths between the microcontroller and antenna. The integrated filter provides high attenuation of unwanted transmitter harmonics, for designers to satisfy the regulations set by radio licensing authorities worldwide.
All devices are in production now. They are offered in a 2.13 x 1.83mm eight-bump wafer-level chip-scale package with a profile below 630 micron after reflow.
