1.7 GHz/2.1 GHz dual-band feed-forward amplifier

This paper proposes a new feed-forward amplifier configuration that simultaneously compensates for the intermodulation distortion components in each band, when signals of different frequency bands are input. The signal cancellation loop and distortion cancellation loop in the proposed feed-forward configuration have a filter and vector regulator for each band. The filter only selects the desired frequency band component from the input signals. Employing the filters means that the whole bandwidth of the input signals is converted to an operable bandwidth for the vector regulators. Therefore, the vector regulator can sufficiently adjust the amplitude and phase of the selected frequency band component. The proposed configuration achieves sufficient intermodulation distortion compensation for each band. A 1.7 GHz/2.1 GHz dual-band, 1-W class feed-forward amplifier is investigated. The third-order intermodulation distortion is less than -70 dBc when the output power is 22 dBm for each band. The saturation output power at 1.7 GHz and 2.1 GHz is 28 dBm and 30 dBm, respectively. These experimental results confirm the validity of the proposed feed-forward amplifier configuration.