Error correction techniques for high-performance differential A/Dconverters |
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Authors: | Tan K.-S. Kiriaki S. de Wit M. Fattaruso J.W. Tsay C.-Y. Matthews W.E. Hester R.K. |
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Affiliation: | Texas Instrum. Inc., Dallas, TX; |
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Abstract: | Error correction techniques that overcome several error mechanism that can affect the accuracy of charge-redistribution analog-to-digital converters (ADCs) are described. A correction circuit and a self-calibration algorithm are used to improve the common-mode rejection of the differential ADC. A modified technique is used to self-calibrate the capacitor ratio errors and obtain higher linearity. The residual error of the ADC due to capacitor voltage dependence is minimized using a quadratic voltage coefficient (QVC) self-calibration scheme. A dual-comparator topology with digital error correction circuitry is used to avoid errors due to comparator threshold hysteresis. A fully differential charge-redistribution ADC implemented with these techniques was fabricated in a 5-V 1-μm CMOS process using metal-to-polysilicide capacitors. The successive-approximation converter achieves 16-b accuracy with more than 90 dB of common-mode rejection while converting at a 200-kHz rate |
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