RTL Design of Joint CFO and IQ-Imbalance Compensator for Narrow-Band Wireless System

摘要

In direct conversion receiver, I/Q imbalance is caused by non orthogonality between in-phase component and quadrature-phase component caused by imperfections of quadrature demodulator. In addition, carrier frequency offset (CFO) occurs as well. In this paper, we present a register transfer level (RTL) design of joint CFO and I/Q imbalance compensator. First, we verify the efficiency of compensation algorithm with computer simulation, and then we show a bit error rate (BER) characteristic. After that, we made an RTL design to compensate CFO and I/Q imbalance. We also measure the efficiency of system in this step by looking at constellation of received signal. Finally, we implement the RTL design of compensation system in a field programmable gate array (FPGA). We show the effect of compensation system by simulation on RTL and verification on FPGA.%ダイレクトコンバージョン受信器では，直交復調器の不完全性によって生じる同相成分と直交成分の非直交性により起因するI／Qインバランスが生じる．またキャリア周波数誤差も同様に発生する．本報告では，狭帯域無線通信システムにおけるCFO及びIQ－Imbalance補正システムのRTL設計を行う．まず，計算機シミュレーションにより本稿で使用する補正アルゴリズムの有用性を示す．その後補正システムのRTLデザインを行い受信信号の信号点配置を確認し，補正効果を示す．最後に，補正システムをFPGAに実装し検証結果を示す．