LAUSR

A background calibration technique for time-interleaved analogue-to-digital converter (TIADC) over Sub-Nyquist frequency timing mismatch is proposed. When the input signal only satisfies the Nyquist sampling theorem of the overall TIADC rather than sub-ADC, both directions of estimation based on correlation and compensation based on differentiator may be opposite to the actual value, which results in a failure calibration. In this Letter, the authors propose a calibration direction correction algorithm which can detect and correct the calibration direction and assure an effective calibration in the whole Nyquist frequency of TIADC. Simulation results show that, for a four-channel 12-bit 1 GS/s TIADC, with f in / f s = 0.45 , signal to noise and distortion ratio (SNDR) is improved from 30.1 to 73.2 dB.