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所在平台: Udemy |
课程主页: https://www.udemy.com/course/vsd-intern-analog-comparator-design-using-sky130/
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课程名称：VSD Intern - 使用Sky130进行模拟比较器设计 课程概述：模拟比较器是一种设备，用于比较两个模拟输入并输出一个数字信号，指示哪一个输入较大。该设备具有两个模拟输入端和一个二进制数字输出。当两个模拟输入信号之间的差异接近零时，输入信号上的噪声会导致数字输出的虚假切换。通过引入滞后效应可以防止由于噪声导致的输出快速变化。滞后效应指的是在不同的输入信号水平下切换输出，即为上升沿和下降沿分别设置两个切换点。高电平触发值（VH）与低电平触发值（VL）之间的差异即为滞后电压（HYST）。 比较器可分为三部分：前端差分放大器、放大阶段和输出阶段。该比较器包括前端差分放大器、对前端差分阶段输出进行放大的放大器、作为缓冲的NAND门以及在输出前起到最终缓冲作用的反相器。NAND门和反相器提高了响应速度并提供了一定的增益。此外，还采用了正反馈差分配置。 比较器的规格包括：传播延迟（输入信号跨越参考电压与输出逻辑状态变化之间的时间差）、输入偏移（输出电压等于零伏特时的输入电压差异）、增益（理想比较器具有无限增益，输出在特定输入电压差下从低变高），此外，还有输出摆幅、输出类型、输入和输出电流及阻抗等多个参数，但本课程主要关注上述内容及滞后效应。 本次网络研讨会将使用ngspice、Xschem和Magic讨论设计、布局和规格细节。
A comparator is a device that compares two analog inputs and outputs a digital signal indicating which input is larger. So it has two analog input terminals and one binary digital output. When the difference between two analog input signals approach zero, noise on the inputs will cause spurious switching of digital output. This rapid change in output due to noise can be prevented by hysteresis. Hysteresis is switching the output high or low at different input signal levels. In place of one switching point, hysteresis introduces two: one for rising edge, and one for falling edge of voltage or current. The difference between the higher-level trip value (VH) and the lower-level trip value (VL) equals the hysteresis voltage (HYST).A comparator can be divided into three distinctive pieces - a front-end differential amplifier, amplifier stage and output stage.This comparator consists ofFront-end differential amplifierAmplifier of the output from front-end differential sageNAND gate to act as buffer as well as incorporate the enable pinInverter to act as final buffer before output. The NAND and Inverter improves the slew and provides a little gain.Positive feedback differential set-up.Various Comparator specifications are listed below:Propagation Delay -The time difference between the input crossing the reference voltage and the output changing the logic state. Generally, comparators are fast Input Offset -The difference between the input voltages at the instance where output voltage equals zero voltsGain-Ideal Comparator has infinite gain and output jumps from low to high at a specific difference in input voltage. Ideal comparators will have a linear transfer curve. There are multiple other parameters like output swing, Output type, input and output current and impedance but we will focus on above including hysteresis.This webinar will discuss all design, layout and specification details using ngspice, Xschem and Magic
