高速OFDM系统中分时ADC失配误差校准技术

Mismatch Correction for Time-Interleaved ADC in High Speed OFDM System

在高速OFDM接收机中利用分时ADC(TIADC)对接收信号进行采样,解决了单片ADC不能满足传输速率高达数Gb/s的通信系统需求的难题。由于TIADC各通道间的不匹配,时钟失配误差和增益失配误差大大影响了系统性能。在传输速率为4Gb/s的OFDM系统中,利用4通道TIADC对接收信号进行采样,对两种失配误差和信道进行联合估计与均衡,并针对64QAM符号调制,对TIADC进行采样精度仿真。仿真结果证明,校准后的9位TIADC可以使系统误码率接近理想值。

Generally a single ADC can not meet the demand of communication system with transmission rate up to several Gb/s. This problem was solved by using the time-interleaved analog-to-digital converter to sample the received signal in the high speed OFDM. However, timing mismatch and gain mismatch greatly degraded the system performance due to the different channel mismatch in TIADC. In the OFDM system with transmission rate up to 4 Gb/s, the received signal was sampled by a 4 channel TIADC. Joint estimation and equalization were carried out to deal with the mismatch error and channel. With regard to the 64QAM symbol modulation, the sampling resolution of TIADC was simulated. Simulation results showed that the 9 bit TIADC calibrated could make the system bit error rate close to the ideal value.