The Circuit Design Blog

Adding a capacitor in parallel with the feedback resistor of an op amp is an easy way of accomplishing low-pass filtering.

This technique works quite well in an inverting amplifier but not necessarily in a non-inverting amplifier.

If the non-inverting amplifier has high gain, the filtering is not bad, but inferior to the inverting case.                                                    

We will illustrate the above by creating and analyzing both circuits. We will use the Spice model of the OPA132 Operational Amplifier.

1. Creating the non-inverting circuit

First we will create the non-inverting circuit. As the components are inserted using their default values, next we will show how to enter the required component values.

2. Creating the inverting circuit

As the two circuits are similar,we will edit and copy the Non-Inverting circuit and then modify where needed.

3. Testing the circuits

In order to step R2, set Parallel Stepping in the Mode Dialog under the Analysis menu. This will step both R2 resistors parallelly.

Select Mode from the Analysis Menu, then in the Analysis Mode dialog select Parameter Stepping from the list.

Next, select Parallel stepping from the Stepping Mode list.

We will test first the Non-Inverting circuit.

Click the output voltage pin of the Non-Inverting circuit and Set the Display signal to „Yes” mode, or check if it is already set so.

Next click at the output voltage pin of the Inverting circuit and set the Display signal to No.

From the Analysis menu select AC Analysis, then AC Transfer Characteristic.

For the lowest curve with a gain of 6db the stopband attenuation is 6dB only.

Now test the Inverting circuit.

To learn more watch our tutorial video.

You can learn more about TINA here: www.tina.com

You can learn more about TINACloud here: www.tinacloud.com

Adding analysis control links to your circuit

In this video (Adding analysis links to TINACloud) we will demonstrate how to add links to your circuits which allow you to carry out most TINACloud analyses simply by clicking the links without using TINAclouds’s menus.

First log-in to TINACloud, then open a circuit by using the File/Open menu. Next, click the T (Insert Text…) icon.

In the dialog box click the “Running man shaped” Action button and select Analysis/Transient.

Now, you can insert the appropriate text, in our case: “Click here to run Transient Analysis”, finally click OK to close the Dialog box. The link will be attached to your cursor and you can place it anywhere on the workplace.

Example:

Analyze the following Opamp827 circuit using  the TINACloud online circuit simulator software  by clicking the link or the image below:

a) Click the following link to analyse the circuit:

Opamp827 circuit

b) Embedded OPAMP simulation: Click the links on the picture to proceed with various analyses.

If you click the “Click here to run AC transient analysis” link, the Transient analysis will automatically run and You can now run cursor on the diagram or close the diagram and make further analyses.

Watch our tutorial video to learn more.

You can learn more about TINA here: www.tina.com

You can learn more about TINACloud here: www.tinacloud.com

In TINACloud you can create your own components from any Spice subcircuit that you have made or downloaded from the Internet. Some device models are stored in Spice .MODEL format. We use the model of the BC846 NPN Bipolar transistor.

This video is an updated version with Integrated circuit editor.

First we will download the BC846.cir file from the internet, than we will upload the model to TINACloud Macro Library.

Next, we will present how to insert the new model to TINACloud.

Finally, we will create the following test circuit to test the new model.

Watch our tutorial video to learn more.

You can learn more about TINA here: www.tina.com

You can learn more about TINACloud here: www.tinacloud.com

In TINACloud you can create your own components from any Spice subcircuit that you have made or downloaded from the Internet. This video is an updated version with Integrated circuit editor.

In this tutorial we will present how you can create a TINA macro component using a THS4121 Spice Subcircuit downloaded previously from the web.

We will present in details how you can specify the names shown as labels of the macro pins. Also, if you wish, you can place them anywhere around the box.

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You can also check the content of the newly created macro by double-clicking on it.

Next, we will demonstrate how you can create an application circuit by adding other components.

Finally we will test the circuit in DC interactive mode. As we will see the model works as expected.

Watch our tutorial video to learn more.

You can learn more about TINA here: www.tina.com

You can learn more about TINACloud here: www.tinacloud.com

In this tutorial video we will show you how you can create a macro from a Verilog (.v) code and use in TINACloud.

You can create macros from VHDL, Verilog-A and Verilog-AMS files in a similar way.

The essential Verilog code of the half adder is 2 lines long only. The Verilog code is much simpler than the equivalent VHDL code. This is one of the great advantages of Verilog.

Similarly to our previous video “Creating Macros from VHDL” we will represent how you can turn the uploaded Verilog file into a Verilog macro. and we demonstrate how to Edit the Macro Input and Output pin names.

If you wish you can move the pin names to the top or to the bottom fields of the editor you can create pins at the top or at the bottom of the macro box.

Of course you can also change the names, for example A to Inp A, B to Inp B and so on.

Finally we will test our newly created macro in TINACloud’s Digital interactive mode along with the previously created VHDL macro and compare the results with the Truth Table of the Half Adder.

Watch our tutorial video to learn more.

You can learn more about TINA here: www.tina.com

You can learn more about TINACloud here: www.tinacloud.com