A 1.2- to 3-GHz tunable feedforward amplifier using broadband distributed phase shifters

In this article, we demonstrate a broadband tunable feedforward amplifier design.For any frequency between 1.2 and 3 GHz, the third order intermodulation distortion (IMD) is reduced up to 18dB and the circuit maintains the spurious free dynamic range over 60 dBc at the output. This technique utilizes the combination of a broadband distributed-element phase shifter (DPS) and a radio frequency feedforward approach to achieve a wideband linearization. The key element is a low-loss, broadband and 360° changeable DPS. Because of its broadband tunable IMD cancellation capability, the proposed design will be very useful in multimode and multi channel wireless communication systems where the high power output with minimized distortion is needed.