运放带宽实验
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●你好，欢迎来到TI Precision Labs（德州仪器高精度实验室）的运放带宽实验环节。
●这个实验会包括计算，SPICE仿真和实际测试。
这些环节会帮助大家对视频中的概念加深理解。
●Hello,and welcome to the TI Precision Lab supplement for op amp bandwidth.●This lab will walk through detailed calculations,SPICE simulations,and real-worldmeasurements that greatly help to reinforce the concepts established in the op amp bandwidth video series.●本实验的计算过程是手工计算的，但也可以使用Mathcad或者Excel等工具。
●因为实验中的SPICE模型是德州仪器提供的通用的运放SPICE模型，所以仿真环节可以使用任何SPICE仿真器。
用TINA-TI实施这些仿真是最方便的。
TINA是免费的SPICE仿真器，可以从TI的网站上下载。
TINA仿真原理图会附在PPT中。
●最后，真实的测试会使用TI提供的印刷电路板。
如果你有标准的实验设备，可以用示波器，波形发生器，波特仪和±15V电源来进行测试。
我们推荐使用国家仪器的虚拟仪器。
这套虚拟仪器是一套多功能集成设备，可以通过USB或者WIFI与电脑连接。
这台仪器提供电源，信号发生器，示波器和5位半的数字万用表，方便进行精确测试。
本章实验中使用的是这套仪器。
●The detailed calculation portion of this lab can be done by hand,but calculation toolssuch as MathCAD or Excel can help greatly.●The simulation exercises can be performed in any SPICE simulator,since TexasInstruments provides generic SPICE models of the op amps used in this lab.However,the simulations are most conveniently done in TINA-TI,which is a free SPICE simulator available from the Texas Instruments website.TINA simulation schematics are embedded in the presentation.●Finally,the real-world measurements are made using a printed circuit board,orPCB,provided by Texas Instruments.If you have access to standard lab equipment, you can make the necessary measurements with any oscilloscope,functiongenerator,Bode plotter,and±15V power supply.However,we highly recommend the VirtualBench from National Instruments.The VirtualBench is an all-in-one test equipment solution which connects to a computer over USB or Wi-Fi and provides power supply rails,analog signal generator and oscilloscope channels,and a5½digit multimeter for convenient and accurate measurements.This lab is optimized for use with the VirtualBench.●首先，根据带宽课程中所学，计算这里所展示电路的闭环带宽和直流增益。
运放的参数在下一页中给出。
●First,calculate the closed loop bandwidth and DC signal gain for the circuit shownhere,using the techniques and equations given in the bandwidth e the data sheet parameters given on the next slide.●该电路选用OPA171。
为了完成计算，你要了解运放的增益带宽积和压摆率。
表中给出了这些参数。
●将答案填到中间的表格中，并仿真出电路的交流传递函数。
●我们在这里给出了答案，方便你验证结果。
●This circuit uses the OPA171.In order to perform the calculations,you need to knowthe gain bandwidth product and slew rate for that device.That value is given here.●Enter your answers in the table in the middle of the slide.The solutions are alreadyprovided to allow you to check your work.●Also complete the AC transfer function for this circuit.Again,the solution is alreadyprovided.●接下来，进行AC传递函数的SPICE仿真分析。
这可以让我们观察运放的闭环带宽和直流增益。
●所需的TINA-TI仿真软件已经嵌入在ppt中。
点击click Analysis AC Analysis ACTransfer Characteristic进行仿真。
仿真频率从10kHz到10MHz●The next step is to run a SPICE simulation analysis for the AC transfercharacteristic.This will allow us to see the op amp’s closed loop bandwidth and DC gain in this configuration.●The necessary TINA-TI simulation schematic is embedded in this slide set–simplydouble-click the icon to open it.To run the analysis,click Analysis AC Analysis AC Transfer Characteristic.Run the analysis from10Hz to10MHz.●你可以看到一个类似这样的仿真结果。
打开光标，测量直流增益或者是最小频率的增益。
结果是26dB，即20V/V。
接着查找-3dB频率点，即增益为23dB的频率点159kHz。
●You should see a result similar to this.Enable the cursor,then check the DC gain,orgain at minimum frequency.The result will be26dB,or20V/V.Next,find the-3dB point,or the frequency where gain drops to23dB.This occurs at159kHz.●在设置PCB前，请确保关闭直流电源。
在软件中，点击直流电源区的电源键来关闭电源。
可以通过观察前面板的LED来确认电源是否关闭。
另外请确保函数发生器也是关闭的。
●Make sure to disable the DC power supply before setting up the test PCB!In theVirtualBench software,click the power button in the DC Power Supply area to turn off the power.Check the front panel of the VirtualBench unit to make sure the LEDs are OFF!Also make sure that the Function Generator is OFF.●为了准备测试用的测试板，按图所示安装电路2的跳针和器件。
●装上JMP6,JMP7,JMP8并在U2上装上OPA171●To prepare the test board for the measurement,install the jumpers and devices oncircuit2as shown here.●Install JMP6,JMP7,and JMP8,as well as the OPA171in socket U2.●现在我们开始通过实际测试来验证我们的计算和仿真。
这一页展示的是TI PrecisionLabs test board（德州仪器高精度实验室测试板）上电路2的原理图。
你可以使用这个电路来测试OPA171的带宽。
●It’s now time to verify our calculations and simulations with real-worldmeasurements.This slide shows the schematic for Circuit2on the TI PrecisionLabs test board.You will use this circuit to measure the bandwidth of the OPA171.●为了让测试板正常工作，你只可以安装电路2的跳针和器件。
不能安装PCB上其他电路里面的跳针和元件。
去掉不相关电路上的跳针和器件，并把放在板子底部的存放区。
