Improving Transmitter Signal Quality by Mitigating Nonlinearities in Power Amplifiers and I/Q Modulators Using UKF

Abstract

A key challenge in deploying high-speed wireless systems is the presence of hardware-induced impairments that degrade performance. These impairments can introduce both in-band and out-of-band interference, severely affecting system reliability. This study focuses on the nonlinear distortions introduced by transmitter components in full-duplex communication systems, specifically the power amplifier (PA) and the in-phase/quadrature (I/Q) modulator. The nonlinear behavior of these elements is recognized as a major source of signal degradation, leading to increased distortion and reduced efficiency. Through comprehensive simulations, the effects of these impairments are evaluated using critical metrics such as Peak-to-Average Power Ratio (PAPR) and Error Vector Magnitude (EVM). To address these issues, the Unscented Kalman Filter (UKF)—a robust algorithm tailored for nonlinear dynamic systems—is employed to estimate and compensate for these distortions. The results demonstrate that the UKF significantly reduces the adverse impact of PA and I/Q modulator nonlinearities, thereby enhancing transmitter performance and overall signal integrity.