Highest Flexibility for Transmitters and Receivers

Digitally Tunable RF Bandpass Filters

The communication industry is faced with a challenge concerning future wireless communication systems. Since the demand on frequency spectrum resources is increasing, wireless communication systems have to deal with coexistence and interference problems. Ever-evolving communication standards and the need for multi-standard communication devices to keep pace with these developments make digitally tunable bandpass filters essential.

The tunable bandpass filters developed by Fraunhofer IIS enhance the capabilities of transceiver units in terms of frequency selectivity, flexibility, and agility. The modules reliably select the required frequency spectrum while rejecting out-of-band signals. They are digitally tunable and can be reconfigured even during operation, which decreases latency and allows for dynamic spectrum access. The reconfigurable bandpass filters are designed to replace conventional filter banks within RF front ends.

We develop tunable bandpass filters for a wide range of applications in the fields of mobile communication, public safety, the Internet of Things (IoT) and satellite communication.

Size comparison between 1 cent euro coin and banpass filter
© Photo Fraunhofer IIS

Miniaturized design – digitally tunable RF bandpass filters

Solderable SMD module (back side)
© Photo Fraunhofer IIS

Solderable SMD module (back side)

SMD module on evaluation board
© Photo Fraunhofer IIS

SMD module on evaluation board

Directly available RF bandpass filters

In the frequency range between 220 and 1400 MHz there are three different bandpass filters obtainable as solderable SMD modules. Corresponding evaluation boards and S-parameters (S2P data files) are available on request.

tBPF-220-425

tunable Bandpass Filter for frequencies from 220 to 425 MHz

tBPF-430-890

tunable Bandpass Filter for frequencies from 430 to 890 MHz

tBPF-630-1400

tunable Bandpass Filter for frequencies from 630 to 1400 MHz

The RF preselection filters enable frequency hopping in 32 steps within a switching period of 12 μs. The adjustable filters cover the frequency range from 220 to 425 MHz, from 430 to 890 MHz, and from 630 to 1400 MHz.

This includes the following selectable RF bands:

  • TV white spaces
  • LTE 800 and GSM 900
  • 433 MHz and 902 MHz ISM band (license-free)
  • 868 MHz short-range device band (license-free)
  • DVB-T/DVB-T2

Custom tunable filters for various frequencies

Customization of directly available bandpass filters

In the range from 220 to 1400 MHz customer-specific adjustments to the RF bandpass filters are possible on request.

Beyond that we provide the following services for various frequencies in the microwave range:

Consulting and evaluation

We carry out requirement analyses and technical feasibility studies in order to find the solution that fits your needs. As part of this process, we provide evaluation boards for performance testing.

Development

We offer customization and further development of prototypes according to your individual requirements.

The benefits at a glance

Increased flexibility of RF front ends

Frequency-agile filters enhance the flexibility of RF front ends, which can be easily adapted to new communication standards and country- or application-specific frequency ranges even during run-time.

Flexible interference management

Based on their high switching speed and reliability, the digitally tunable filters help to avoid interference between wireless systems and enable flexible coexistence solutions like cognitive radio.

Simple implementation and operation

Replacing filter banks with digitally tunable filter modules reduces the size of RF front ends. The filters can be easily adjusted by a 3-wire SPI control signal and operate at a constant supply voltage of up to 3.5 volts.

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Digitally tunable RF filters