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RF front-end filters address a variety of functions such as band-pass, low-pass, and high-pass filters. RF filters can be easily integrated into front-end modules using ST's thin-film RF IPD process. This process integrates high-quality passive RF components into a single glass or high-resistance silicon substrate.

What are RF filters used for?

RF filters enable or inhibit selected signals or frequencies to eliminate interference or the transmission of unwanted signals.

Types of RF filters

There are four basic types of RF filters: high-pass, low-pass, band-pass, and band-reject filters.

  • Low-pass filters:

    There are various types of low-pass filters. The main use of this filter is to suppress the harmonics of the RF amplifier. This characteristic helps avoid unwanted interference in different transmission bands. High frequency filtering give signals a sharper and clearer quality.

  • High-pass filters:

    In contrast to low-pass filters, high-pass filters attenuate frequencies below a certain threshold so only high-frequency signals can pass. The high-pass filter can be used in combination with a low-pass filter to form a band-pass filter.

  • Band-pass filters:

    Band-pass filters are circuits that pass signals of two different frequencies and attenuate signals outside a given range. ST RF IPD band-pass filters do not use an external power source and integrate passive components like inductors and capacitors. Active band-pass filters instead need external power and active components like integrated circuits and transistors.

    Band-pass filters are commonly used in wireless receivers and transmitters. Band-pass filters minimize the bandwidth of output signals to allow transmitters to send data at desired speeds and formats.

    Band-pass filters in receivers only allow desired frequencies to be decoded, while blocking the inclusion of other signals from unwanted frequencies.

    Overall, a well-designed bandpass filter can easily maximize signal quality while minimizing conflicts and interference between signals.

  • Band-reject filters:

    A band-reject or notch filter allows most signal frequencies to pass, but attenuates specific frequency ranges to very low levels. It is the opposite of the band-pass filter.

Which RF filter do i need?

Our RF filters address a wide range of applications such as mobile and connected devices, cellular base-stations, and consumer applications.

For Bluetooth applications, the MLPF-WB-01E3 is an impedance matched harmonics filter optimized for our dual-core, multiprotocol wireless STM32WB55 microcontrollers. It requires seven times less PCB space than the equivalent L-C discrete solution.

The new MLPF-WB55-02E3 is tailored to match the output impedance of the STM32WBVxxx series. The new MLPF-WB-01E3 is a matched filter companion chip for all STM32WB55Cx, STM32WB55Rx, STM32WB35xxx, STM32WB50xxx, and STM32WB30xxx.

Associated RF Microcontroller Matched Low Pass Filter
Companion Chip
Frequency (MHz) Integrated filter Size Package
STM32WB55Cx/Rx, STM32WB50Cx, STM32WB35Cx,
STM32WB30Cx BLE 5.0
MLPF-WB-01E3 2400-2500 Yes 1.5 mm x 1.0 mm Bumpless CSP
(LTCC assy-like)
STM32WB55Vx BLE 5.0 MLPF-WB55-02E3 2400-2500 Yes 1.5 mm x 1.0 mm Bumpless CSP
(LTCC assy-like)

What are the main benefits of using ST's RF filters?

ST's RF filters ensure design simplification and performance optimization. Our technology of passive integration on high resistivity substrate provides higher system integration, especially for RF module integration. It also significantly improves reliability and can significantly reduce the bill-of-materials with respect to alternative discrete solutions.

Benefits of ST's RF IPD technology