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This paper proposes a fully digital calibration of timing mismatch for undersampling Time Interleaved Analog-to-Digital Converter (TI-ADC) employed in Software Defined Radio (SDR) receivers. The proposed calibration scheme employs an ideal differentiator filter, a Hilbert transform filter and a scaling factor to compute the derivative of the input in any Nyquist Band (NB). The efficiency of the proposed technique is shown using a four-channel undersampling 60 dB SNR TI-ADC clocked at 2.7 GHz. Monte Carlo simulations show SNDR and SFDR improvements of respectively, 18 dB and 21 dB over the first three NBs.

This paper proposes a new all-digital calibration technique suppressing the timing mismatch effect in Time-Interleaved Analog-to-digital Converters (TIADCs) for input at any Nyquist Band (NBs) using the equivalent polyphase structure of the TIADC. The correction technique is simple and does not require the adaptive digital synthesis filters. The timing mismatch is estimated based on an adaptive stochastic gradient descent technique, which is a promising solution for TIADCs operating at very fast sampling rate. The digital circuit of the proposed calibration algorithm is designed and synthesized using 28nm FD-SOI CMOS technology for the 11-bit, 60dB SNR TIADC clocked at 2.7GHz with the input in the first four NBs. The designed circuit occupies the area of 0.05mm 2 and dissipates the total power of 41mW.

This paper presents a practical implementation of all digital calibration algorithm for the gain and timing mismatches in undersampling Time-Interleaved Analog-to-Digital Converter (TI-ADC). A new Least Mean Square (LMS) based detection scheme is proposed to increase convergence speed as well as to enhance the estimate accuracy. Monte Carlo simulations for a four-channel undersampling 60 dB SNR TI-ADC clocked at 2.7 GHz show that SFDR can achieve approximately 90 dB SFDR within the stable point of the channel mismatch coefficients over the first three Nyquist Bands. The proposed architecture is implemented and validated on the Altera FPGA DE4 board. The synthesized design consumes a few percentages of the hardware resources of the FPGA chip and work properly on a Hardware-In-the-Loop emulation framework.978-1-4799-8391-9/15/$31.00 ©2015 IEEE