An Integrable Analog Domain Linearization Architecture for Power Amplifiers in MIMO Systems Using Spectrum Shaping Circuit with Nonlinear Feedback

This paper proposes an integrable analog domain linearization architecture for power amplifiers (PAs) in multi-input multi-output (MIMO) systems, using a spectrum shaping circuit with nonlinear feedback. This architecture consists of a nonlinear distortion extracting loop and an N-order spectrum shaping circuit. The extracting loop aligns the PA input and output signals in amplitude with a 180-degree phase difference and then adds them together to extract the nonlinear distortion signal. The spectrum shaping circuit reshapes the spectrum of the extracted nonlinear distortion signal using N identical analog chains but with different group delays and attenuation parameters, and finally injects it back to the PA input to suppress the nonlinear distortion of the target frequency. Moreover, the delay in the remaining spectrum shaping channels has multiple relationships to the first channel, which can be easily integrated into the PA design stage with low complexity. Particularly, the center frequency of the nonlinearity suppression can be easily shifted by modifying the attenuation parameters in the N-order spectrum shaping circuit. We designed the proposed architecture using off-the-shelf discrete components and demonstrated its nonlinear distortion suppression performance at different target frequencies for the PA chip CMPA006002F.