基于时间交错采样的低功耗示波器设计

发布时间：2018-02-16 14:27

本文关键词： DSO 时间交错采样 TIADC FPGA 失配误差补偿拉格朗日插值　出处：《西南交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：示波器广泛的用于信号的分析与测量,扮演着不可或缺的重要角色。随着技术快速的发展,数字存储示波器性能进一步加强,逐渐取代了模拟示波器。而便携式示波器作为示波器发展的一个分支,克服了普通数字存储示波器体积庞大,功耗较高,不便于携带等缺点,广泛的应用于一些特殊的应用场合。为满足对复杂带宽信号进行实时捕获与测量要求,提高采样率对示波器来说显得尤为重要。在现有的条件下,时间交错采样技术可以有效的提高系统的采样率,从而突破单片模数转换器芯片转换速率对系统采样率的限制,实现高速采样。虽然TIADC(时间交错采样模数转换器)可以提高系统采样率,但是由于ADC通道之间的不一致性以及采样时间间隔不均匀等因素会引入误差,导致示波器性能下降。因此本课题主要从如下两个方面展开。一方面,本课题将基于FPGA设计一款便携性低功耗数字存储示波器。另一方面,本课题将对TIADC系统中的失配误差进行估计和校准,提高系统的无杂散动态范围。具体内容如下:根据TIADC系统的结构及原理,推导TIADC的系统模型。从实际应用场景分析ADC通道之间失配误差产生原因及来源。并根据得到的数学模型分析TIADC在理想情况下和误差存在的情况下输出的频谱特性。提出了一套完整的TIADC失配误差消除方法。该方法主要分为失调误差估计以及失调误差补偿两部分。该方法在具有很高的失配误差参数估计精度的情况下依然具有较低的计算复杂度。失调和增益失配误差补偿是基于误差参数来实现的,而采样时间失配误差补偿则是采用一种简化拉格朗日插值法来实现。该补偿结构采用单精度浮点设计,并在严重的失配误差条件下(高达5%的失调和增益误差以及10%的超前的或者滞后的采样时间误差)对该结构进行了仿真。该补偿的补偿效果使无杂散动态范围提升达53dB。除此之外,该补偿结构并不受TIADC通道数目的限制。基于单片FPGA成功开发了一款便携式低功耗数字存储示波器。为满足输入信号的宽动态范围要求,设计了增益灵活可调的模拟前端电路。采用双通道模数转换器设计,支持时间交错采样模式,成倍的提升了示波器的采样率。分析了多种内插方式,采用了正弦插值解决了采样点不足时恢复波形的问题。
[Abstract]:Oscilloscopes are widely used in signal analysis and measurement, playing an indispensable role. With the rapid development of technology, the performance of digital storage oscilloscope is further enhanced. The portable oscilloscope, as a branch of the oscilloscope development, overcomes the shortcomings of the ordinary digital storage oscilloscope, such as large volume, high power consumption, and not easy to carry. In order to meet the requirements of real-time acquisition and measurement of complex bandwidth signals, it is particularly important for oscilloscopes to improve the sampling rate. The time-interlaced sampling technique can effectively improve the sampling rate of the system, thus breaking through the limitation of the conversion rate of the single-chip A / D converter chip to the sampling rate of the system. Although TIA DC (time interlaced sampling A / D converter) can improve the sampling rate of the system, because of the inconsistency between the ADC channels and the uneven sampling time interval, the error will be introduced. As a result, the performance of oscilloscope is degraded. Therefore, this subject is mainly developed from the following two aspects. On the one hand, this project will design a portable low-power digital storage oscilloscope based on FPGA. This subject will estimate and calibrate the mismatch error in TIADC system to improve the dynamic range of the system without stray. The specific contents are as follows: according to the structure and principle of TIADC system, The system model of TIADC is derived. The causes and sources of mismatch errors between ADC channels are analyzed from the practical application scene. According to the obtained mathematical model, the spectrum characteristics of TIADC output under ideal conditions and the existence of errors are analyzed. In this paper, a complete method of TIADC mismatch error elimination is proposed. The method is mainly divided into two parts: mismatch error estimation and offset error compensation. This method still has high precision of mismatch error parameter estimation. Offset and gain mismatch error compensation is based on error parameters. The compensation of sampling time mismatch is realized by a simplified Lagrangian interpolation method. The compensation structure is designed with single precision floating-point. The structure is simulated under the condition of serious mismatch error (up to 5% misalignment and gain error and 10% lead or lag sampling time error). The compensation effect of the compensation makes there is no stray dynamic range. Up to 53dB. in addition, The compensation structure is not limited by the number of TIADC channels. A portable low-power digital storage oscilloscope is successfully developed based on monolithic FPGA. An analog front-end circuit with flexible gain and adjustable gain is designed. The dual-channel analog-to-digital converter is designed to support time-staggered sampling mode, which can increase the sampling rate of oscilloscope exponentially. Sinusoidal interpolation is used to solve the problem of waveform recovery when sampling points are insufficient.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM935.3

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