The front-end track-and-hold (T&H) circuit is one of the most critical components of an analog-to-digital converter (ADC). Considering a pipelined ADC, it is known that the errors of each stage of the pipeline will be attenuated by the interstage amplifiers, however, the errors of the front-end T&H will be directly present in the output codes produced by the ADC. Because of this, the accuracy requirements for the front-end T&H are the most stringent of all sample-and-hold stages in the ADC. Recently, the design of open-loop T&H circuits is getting more and more attention. Advantages of open-loop circuits include low power-consumption, high-speed operation, simple reliable design, and ability to operate at low power-supplies. However, a major disadvantage of open-loop circuits is their relatively poor linearity. Therefore, unless some correction technique is applied, the use of open-loop architectures is limited to converters with a low accuracy (up to 8-bit). Though some digital correction techniques for the improvement of the linearity of open-loop structures have been presented previously , , they are limited to specific implementations or spe- ci¯c types of non-linearity (e.g. third order distortion). In this paper, a general digital post-correction method is presented. This method improves the linearity of the front-end T&H circuit in the digital domain independent on the actual T&H design or the shape of the non-linearity. The method includes both a measurement procedure to determine the actual non-linearity and a correction algorithm. As it is not relying on accurate reference components, it can be integrated easily on-chip. The method was verified by simulations on a T&H circuit designed on transistor-level in a 0:18¹m technology, and shows that its linearity can be improved from 9.5-bit up to 13.5-bit, while operating at a sample frequency of 500MHz.
|Title of host publication||Proceedings of the 17th ProRISC, Annual Workshop on Circuits, Systems and Signal Processing (ProRISC 2006) 23 - 24 November 2006, Veldhoven, the Netherlands|
|Place of Publication||Utrecht, the Netherlands|
|Publication status||Published - 2006|
|Event||2006 Annual Workshop on Circuits, Systems and Signal Processing (ProRISC 2006) - Veldhoven, Netherlands|
Duration: 23 Nov 2006 → 24 Nov 2006
Conference number: 17
|Conference||2006 Annual Workshop on Circuits, Systems and Signal Processing (ProRISC 2006)|
|Abbreviated title||ProRISC 2006|
|Period||23/11/06 → 24/11/06|
Harpe, P. J. A., Zanikopoulos, A., Hegt, J. A., & Roermund, van, A. H. M. (2006). Digital Post-Correction of Open-Loop Track-and-Hold Circuits. In Proceedings of the 17th ProRISC, Annual Workshop on Circuits, Systems and Signal Processing (ProRISC 2006) 23 - 24 November 2006, Veldhoven, the Netherlands (pp. 33-39). Utrecht, the Netherlands: Technology Foundation.