适用于TIADC时间误差校准的斩波调制算法

Calibration technique for time-interleaved ADC using chopping modulation

传统的时间交织模数转换器(TIADC)时间误差斩波调制校准算法无法向多通道推广,改进的时间误差斩波调制校准算法将单通道与相邻通道输出相加后分别斩波再求和来提取出时间误差,使其能适用于任意通道误差的提取,时间误差补偿采用一阶泰勒近似来实现,避免了传统算法中复杂滤波器设计。然而,当输入信号频率超过子通道奈奎斯特频率时,校准算法的校准方向会出错,从而导致校准失败。因此,设计了一种校准方向修正算法,能够满足整个系统奈奎斯特频率范围内的有效校准。仿真结果表明,应用于一个4通道、1 GS/s、12位的TIADC,当输入信号频率为450 MHz时,系统的信号噪声畸变比(SNDR)由28.4提高到73.1 dB,系统的无杂散动态范围(SFDR)由30.7提高到88.9 dB。

The traditional TIADC timing mismatch chopping modulation calibration cannot be extended to multi-channel.The improved timing mismatch chopping modulation calibration algorithm adds the single channel and the adjacent channel output to detect the timing mismatch.It can be applied to the detection of arbitrary channel timing mismatch.Compensation is implemented by first-order Taylor approximation,which avoids the complex filter design in traditional algorithms.However,when the input signal frequency exceeds the Nyquist frequency of sub-channel,the calibration direction of the calibration algorithm will be wrong,resulting in the failure of calibration system.Therefore,this paper proposed a new calibration direction correction algorithm that can meet the effective calibration of the Nyquist frequency range of the whole system.Simulation results show that when applied to a 4-channel,1 GS/s,12-bit TIADC and when the input signal frequency is 450 MHz,the signal-to-noise distortion ratio(SNDR)of the system is increased from 28.4 to 73.1 dB,and the spurious-free dynamic range(SFDR)is increased from 30.7 to 88.9 dB.