How it works
How do you achieve signal isolation in a tunable duplexer?
In two-way wireless communication, smart devices and base stations transmit and receive signals simultaneously, using different frequencies.
In FDD (frequency division duplexing), these data transfers – referred to as uplink and downlink, occur concurrently at different frequencies.
Each device contains a radio front-end module with a power amplifier in the transmit path (Tx) to amply transmission and a low-noise amplifier in the receive path (Rx) to amplify signals for reception.
The transmit signal is amplified to reach the base station reliably, but its strength, combined with band-edge emissions and intermodulation distortion, can create unwanted interference in the receive band. A filter is used to suppress these spurious components.
On the receive side, the signal is much weaker and a receive filter, such as a SAW filter, can isolate the desired signal and block unwanted transmission interference.
Forefront RF is pioneering a fully tunable filter architecture using inductors and digitally controlled variable capacitors.
This approach provides flexibility but not the same high selectivity as SAW filters, allowing some transmit energy to leak into the receive path and cause self-interference.
This is a challenge the industry has faced for decades, and Forefront RF is the first to solve it with a built-in self-interference canceller operating at the receive frequency to deliver the extra isolation needed between transmit and receive.
The cancellation network generates a phase-inverted copy of the interference and adds it to the receive signal to cancel it out. Intelligent software algorithms control both the tunable filters and the cancellation network, adapting in real-time to changing radio environments.
This breakthrough unlocks a long-missing piece in mobile RF: a truly tunable, reconfigurable duplexer that combines integration, performance, and flexibility in a way fixed-filter systems cannot match.
Forefront RF is ready to help you unlock the full potential of reconfigurable radio front-ends.