Mixed $H_2/H_{\infty}$ Output Feedback Controller Design for PLL Loop Filter with Uncertainties and Time-delay

시간지연과 불확실성을 가지는 위상동기루프의 루프필터에 대한 혼합 $H_2/H_{\infty}$ 출력궤환 제어기 설계

In this paper, a robust mixed H$_2$/H$\_$$\infty$/ output feedback control method is applied to the design of loop filter for PLL carrier phase tracking. The proposed method successfully copes with large S-curve slope uncertainty and a significant decision delay in the closed-loop that may exist In modern receivers due to a convolutional decoder or an equalizer. The objective is to design an output feedback controller which minimizes the H$_2$performance while satisfying the H$\_$$\infty$/ performance to guarantee the gain margin and phase margin for linear time invariant(LTI) polytopic uncertain systems. LMIs based approach is given to solve this problem. We can verify the H$\_$$\infty$/ performance satisfaction and minimize the phase detector error through the simulation result.