Influence of Non Quadrature of Phase Shifter to Adaptive Interference Cancellation System

This paper investigates the influence of non quadrature of phase shifter to the convergence characteristic and interference cancellation ratio (ICR) of a single channel analog adaptive interference cancellation system (SAAICS). We established the analysis model and solved the transient and steady-state characteristics of weights. Through the analysis of steady-state error and ICR, we obtained the rule of ICR variation with quadrature offset angle. And that rule with different interference signal phase was gained. The non quadrature of phase shifter decreases the average convergence speed. The more quadrature offset is, the low average convergence speed will be. But the ICR does not decrease absolutely with the increase of quadrature offset. It is related with the interference signal phase. For different interference signal phase, the rules of ICR variation with different quadrature offset angles are nearly consistent. The analyses are in agreement with the computer simulation. For non quadrature of phase shifter, the system is time-variant. When the signal frequency is higher, the influence of the time-variation is smaller.