A Multiphase Multipath Technique With Digital Phase Shifters for Harmonic Distortion Cancellation

Nonlinearities in transmitter circuits, such as power amplifiers, cause degradation in system performance and adjacent-channel spectral growth interference. Polyphase multipath is considered among the techniques that can compensate the nonlinearities, creating a clean output spectrum. However, the polyphase technique requires analog phase shifters that consume considerable power. Aiming at reducing the power consumption, this brief presents a novel multiphase multipath technique with digital phase shifters. The technique is capable of canceling most of the harmonic and intermodulation products produced by a current-output nonlinear circuit to achieve the required linearity. The proposed system has advantages over existing polyphase techniques in power consumption, accuracy, and flexibility. However, it lacks image rejection and local oscillator harmonic cancellation. Detailed analyses and simulations of the new technique are provided to show the effectiveness of the harmonic distortion cancellation.