Abstract
This letter presents a fully integrated on-chip digital mismatch compensation system for time-based time-interleaved (TI) data converters. The proposed digital compensation features blind calibration of gain, offset, and timing mismatches. The implemented system uses time-based sampling clock mismatch detection, achieving convergence within 32K samples, which is on par with analog-assisted background methods. A specialized filter structure compensates for timing mismatches of magnitude up to 0.21 of the sampling period, nearly triple the range of other published digital compensation methods, and is effective for input signals up to 0.92 Nyquist bandwidth. The on-chip digital correction achieves suppression of all mismatch tones to levels below −60 dBc while running fully in the background. The operation is demonstrated with an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times $ </tex-math></inline-formula> TI 2-GS/s analog-to-digital converter (ADC) prototype chip implemented in a 28-nm CMOS process.
Highlights
M ODERN wireless communication applications require analog-to-digital converters (ADC) with gigahertz range bandwidth (BW)
This paper presents a fully integrated on-chip digital mismatch compensation solution with a unique background skew correction scheme facilitated by the time-based converter architecture
It employs a least-mean-square (LMS) algorithm for blind gain and offset calibration and a fully digital skew mismatch estimator, achieving convergence within 32K samples, which is comparable to other analog-assisted methods
Summary
M ODERN wireless communication applications require analog-to-digital converters (ADC) with gigahertz range bandwidth (BW). Analog-assisted digital methods can provide fast and accurate calibration for the mismatch errors. They require auxiliary circuits [1], [2] or reference ADCs. Split TI-ADC is proposed for reference-free calibration [3]. This paper presents a fully integrated on-chip digital mismatch compensation solution with a unique background skew correction scheme facilitated by the time-based converter architecture. It employs a least-mean-square (LMS) algorithm for blind gain and offset calibration and a fully digital skew mismatch estimator, achieving convergence within 32K samples, which is comparable to other analog-assisted methods.
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