300MHz手持示波表隔离通道设计

发布时间：2018-07-01 15:32

本文选题：手持隔离示波表 + 模拟信号隔离　；参考：《电子科技大学》2016年硕士论文

【摘要】：手持隔离示波表采用独立的电气绝缘信号通道,能够对多个没有公共参考地的混合电路同时进行浮地测量,避免偶然接地短路所造成的危险。随着复杂电子信号的隔离测试需求不断增长,对隔离示波表的输入带宽提出新要求的同时,对仪器的安全规范要求也越来越高。模拟通道是手持隔离示波表的关键模块之一,本课题围绕通道隔离电路以及通讯接口隔离方式进行了研究。设计并实现了300MHz隔离通道,以及安全隔离通讯接口功能。主要包括以下三个方面的内容:一、设计了模拟信号隔离电路。输入的模拟信号隔离电路采用分路径电路的传输方式,即基于宽带隔离变压器的高频隔离传输路径和基于线性光耦的低频隔离传输路径,然后叠加组合。通过反复设计和验证,实现了DC至300MHz的模拟信号隔离电路。二、设计了电源隔离电路和数字控制信号隔离电路。根据通道隔离电路的设计要求,电源隔离电路采用了高效率的隔离电源和低纹波的低压差线性稳压器,并设计了可软件控制的电源控制电路,能够根据示波表的工作模式,实现动态电源管理,在一定程度上降低示波表的功耗。采用了低功耗数字信号隔离芯片,设计了通道控制电路,实现了对模拟通道工作状态控制。三、为了进一步保证示波表的使用安全,本文对示波表的对外接口也做了相应的电气隔离设计,包括USB通信接口隔离、外触发输入信号隔离和方波校正输出信号隔离,实现了示波表内部工作电路对外界完全电气隔离,提高了安全性能。最后分别对设计的电路进行性能指标测试,结果表明设计的模拟信号隔离电路带宽达到了300MHz,满足了设计指标要求,而且方波校正输出隔离信号和USB隔离接口等也满足设计功能要求,并已运用于某型号数字示波表。
[Abstract]:The hand-held isolated oscillometer uses an independent electrical insulated signal channel, which can be used to measure several mixed circuits without common reference at the same time, so as to avoid the danger caused by accidental grounding short circuit. With the increasing demand for isolation and testing of complex electronic signals, new requirements for the input bandwidth of isolated oscillograph are put forward, and the requirements for the safety specifications of instruments are becoming more and more high. Analog channel is one of the key modules of handheld isolation oscillometer. Designed and implemented the 300 MHz isolation channel, as well as the security isolation communication interface function. It mainly includes the following three aspects: first, the analog signal isolation circuit is designed. The input analog signal isolation circuit adopts the transmission mode of split-path circuit, that is, the high-frequency isolated transmission path based on wideband isolation transformer and the low-frequency isolation transmission path based on linear optocoupler, and then superposition the combination. Through repeated design and verification, the analog signal isolation circuit from DC to 300 MHz is realized. Secondly, power isolation circuit and digital control signal isolation circuit are designed. According to the design requirements of the channel isolation circuit, the power isolation circuit adopts the high efficiency isolating power supply and the low ripple low voltage differential linear voltage regulator, and designs the software controlled power supply control circuit, which can work according to the mode of the oscillograph. Dynamic power management is realized to reduce the power consumption of oscillograph to a certain extent. The low power digital signal isolation chip is used to design the channel control circuit to control the working state of the analog channel. Third, in order to ensure the safety of the oscillometer, the external interface of the oscilloscope is also designed for electrical isolation, including USB communication interface isolation, external trigger input signal isolation and square wave correction output signal isolation. The internal working circuit of the oscilloscope is completely isolated from the outside, and the safety performance is improved. Finally, the performance indexes of the designed circuits are tested, and the results show that the bandwidth of the designed analog signal isolation circuit reaches 300 MHz, which meets the requirements of the design index. The square wave correction output isolation signal and USB isolation interface also meet the design requirements and have been applied to a certain type of digital oscilloscope.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM935

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