A small window will open, use the 'Attached Cursor' drop down box, select 1st & 2nd. - Use the db() function to plot the gain of your system in dBs. IP3 point simulation 16 4. Let’s start the circuit simulation using LTSpice, to open a new schematic editor. Further, the state_of_flux. So one should use plot vdb(out) for the gain in dB and plot ph(out) for the phase. Input and output stability circles lays outside of smith chart, which means that amplifier is unconditionally stable or stable with all source and load impedances. You can view frequency response as a bode plot, on the Cartesian coordinate plane with the real and imaginary axis and you can view it as a Nyquist plot. Go to File, select the New schematic. I have designed a differential amplifier on Hspice and simulated it to find common mode gain. When designing opamps in analog IC design, it is frequently required to plot the open loop gain/phase. Aleks. Click on a new schematic, go back to inverting circuit schematic and click on the Copy icon and left-click and drag until you cover the entire circuit. Now in order to calculate CMRR I need to find differential gain. This can be done using techniques demonstrated in the LTspice Tips on BI and BV Arbitrary Source Examples and Mathematical Integration along with simulation parameter stepping. GBW = Gain x -3dB Frequency = 10 * 4MHz = 40MHz . LTspice has done all the necessary division and dB calculation arithmetic . The "wire" or connection line always printed at very thin line. LTspice uses waveform compression, so this parameter is of little value and can be omitted or set to zero. Now the graphs are o.k., but titles and labels are not yet satisfactory. 12. This should be somthing like db(V(vout)/V(vin)) where V(vin) and V(vout) are the names of your input and output voltage signals. But we want to see magnitude (or gain) and phase, like in a Bode plot. The output waveform will be a bode plot showing you the amplitude and phase across a specified frequency range. At 1 MHz, the phase shift was 90 degrees and the gain was 4.9. I want to replicate this structure in LTspice where the components 1, 3 et 4 are resistors with the same resistance R and 2 et 5 are two capacitors and opamp LT1356. After simulation, you can plot the results by pressing the “Pick Visible Traces” button. by Gabino Alonso. The Double Balanced Mixer (= ring modulator) 20 4.1. 3. Contributor; Posts: 26 ; Country: How to create control-to-output transfer function plots in LTSpice « on: April 27, 2020, 04:04:13 pm » I have a converter which has a buck pre-regulator and then a resonant stage inverter. However, if Tstart is specified, the waveform data between zero and Tstart is not saved. In this article, we will focus on how to set up a independent voltage source for analysis. Hello, I'm looking to duplicate functionality from LTSpice in PSpice. Author Topic: How to create control-to-output transfer function plots in LTSpice (Read 229 times) 0 Members and 1 Guest are viewing this topic. In addition, LTspice can use auxiliary units as shown in the following table. Fundamentals 20 4.2. Setting up a simulation for this that works isn't particularly difficult, but setting one up that works well and that runs fast enough can be a … fand ich keine Möglichkeit, dies mit Pandas zu tun, da das Format der Daten wie folgt aussieht: 5.00000000000000e+006\t(2.84545891331278e+001dB,8.85405282381414e+001°) Figure 9 shows the plot of versus the range of frequency. Next, I will introduce the current source. As shown in the "Gain/Phase vs Frequency" plot in the datasheet, your LTspice simulation results are fine and almost identical at G=10 closed loop configuration with Gain Bandwidth Product at -3dB point equal to 4MHz. ngspice plotting procedures here need some manual tweaking. In LTSpice, the text file must have four columns as shown in the first image: '+' to allow for multiple lines, frequency value, The ratio of Stop Time: Maximum Timestep determines how many calculations LTspice must make to plot a wave form. Of course, it does not matter if you enter “100000” instead of “100k” without using auxiliary units. We get the inverted output plot. 1. Then we will get the plot in linear scale which is shown in below. The simulator gives the voltage across and current through the capacitor. How to Plot Switching Supply Efficiency With a Stepped Load Current. Move your pointer over the new cross-bar and a number "1" will appear. Next, after cascading shunt resistor at the output of amplifier, constant gain, noise figure and input/output stability circles are drawn in figure 4. Tstop is the duration of the simulation. simulation will run and a plot window will appear in the LTSpice program as shown in Fig. Please help me to obtain the charge-voltage chara of a capacitor in circuit simulator (Like LTSpice / QUCS). Auxiliary unit of LTspice . Contributor; Posts: 15 ; Country: LTSpice loop gain stability analysis « on: November 04, 2015, 01:01:00 am » Hi all, I'm in the process of designing a 13.8V power supply, capable of delivering around 20A of continuous current (HAM, yup). LTspice always defaults the start time to zero seconds and going until it reaches the user defined final time. LTspice Simulation of the complete 137MHz LNA 9 3.3.1. There are several options with AC analysis. Noise figure simulation 12 3.3.4. i.e log f (frequency) in x axis and gain( in db) in y axis.For calculating gain in linear scale, first you need to convert the plot in linear scale. A pop-up window showing the plottable traces will appear. Save the schematic as a non-inverting circuit. - - - Updated - - - Here is a very basic (with no compensation) current source, it is unstable. Phase Bode Plot: - Go to add a trace. I've created a multistage amplifier in LTSpice IV and want to use actual measured hfe (Beta) values for each of the transistors, though I can't find an easy way to modify them. I have a problem with the Bode plot of an OTA with LTSpice. This is a means of managing the size of waveform files by allowing startup transients to be ignored. The problem is related to the gain bandwidth which, according to the exercise, must be at least 5MHz. The loop gain plot now shows +21dB @ 180deg phase shift, this is positive feedback and we have ourselves an oscillator. Components required to design a Common Drain Amplifier are NMOS, voltage source, wire, and ground. The goal is to be able to plot a set of AC gain and phase data from an included text file, allowing me to compare that response to the one of a circuit I'm actively developing. LTSpice, Reading values from plot. One way of doing that is to use a high feedback resistor and very high capacitance so the feedback network has an extremely low corner frequency: This works fine unless your opamp drive capability is low, in which case you can increase the feedback resistor. As shown in Fig. this is the schema I made this is the bode plot: I think it's wrong because the max value of the gain is -50 dB while I need to find the frequency at … The piccy clearly says V(output). the CM gain reciprocal (which as I understand it is the CMRR). LTspice can plot eye diagrams - a feature which is only semi-documented. Magnitude Bode Plot: - Go to add a trace. LTspice: Basic Steps in Generating a Bode Plot of SMPS. Frequency response is plotted in semi-log. Now place the NMOS in the schematic, click on to the component symbol, and you would get the select component symbol popup from the list select the NMOS. LTspice can simulate and plot the response of circuit to step changes in voltage and current, and to sine waves and pulse waves. Figure 4. To achieve this, right click on the y axis and you will see a pop up screen. S Parameter Simulation of the LNA 10 3.3.3. It has Gnd node, voltage source, resistor and capacitor. My circuit designs should be regarded as experimental. We can verify that it makes sense against our original results obtained above: At 0.1 Hz, the phase shift was 180 degrees and the gain was 49.7k. For the types of analysis, please see the following article. So the plot of a/v(out) is in fact a plot of v(in)/v(out), i.e. Stability control 14 3.3.5. So how do I get a -7 dB voltage gain relative to an 80 nA AC current sweep? 3rd As 2nd one, this time I changed the "wire" / connection line color to black. Transient analyses always start at time equal to zero. Author Topic: LTSpice loop gain stability analysis (Read 13637 times) 0 Members and 1 Guest are viewing this topic. Simulation in the time domain using a 137MHz input signal 15 3.3.6. Fig. I just followed the example below but as I simulate the circuit in LTSpice with LEVEL 1 MOS parameters I get a wrong Bode plot (find below). Select “Linear” from the three options shown. The result shows that, at frequency of 10kHz, the output impedance . ICMR ranges from 0.6V-1.2v. Choosing and setting the operating point 9 3.3.2. - Use the P() function to plot the phase response of your system. Start a new schematic and create the circuit shown below. 1. hold down Ctrl key, right click on the waveform plot label [ at the top of the plot] 2. Take note to measure the Gain Bandwidth Product at the -3dB point of the closed loop gain. But before we move on, we have to streamline our approach. For example, we need a non-inverting circuit. LTspice enables them when adding the insufficiently documented, baudrate-option LTspice requires setting of the signal source when simulating. Although they work in simulation, their component values may need altering or additional components may be necessary when the circuits … As in other plots, you can use the mouse and right-click on axes values to change axis setup. How can I solve the problem? Designing and Simulation of LNA using LTspice and Matlab. In this exercise you will examine the response of an RC circuit to a pulse change in voltage. Table 1 summarizes the results for the simulation in LTSpice and theoretically calculation on emitter current, voltage gain, input- and output-impedances of the BJT common emitter amplifier. Run the sim and create a plot. Attached 3 printed schematic in PDF using Bullzip PDF Printer, but on LTSpice XVII though : 1st Using the default color scheme 2nd As for testing, I changed the junction to red while component body to pink. This will give you the Bode plot that you were expecting with the Gain at the top and the Phase at the bottom. However, the LTspice Nyquist plot manages to combine a curve whose shape corresponds to an infinite frequency range with the numerical frequencies that we would expect from a Bode plot. The following two "Plot Settings" menu items related to eye diagrams [select a plot pane (.raw)] Plot Settings->Eye Diagram->Enable Plot Settings->Eye Diagram->Properties They are usually disabled. Ich möchte einige Daten von LTspice mit Python und Matplotlib plotten, und ich suche nach einer Lösung zum Importieren der exportierten Plot-Daten von LTspice in Python. The gain is voltage dB. \$\endgroup\$ – Paul Uszak Mar 23 '16 at 1:01 \$\begingroup\$ It's probably not relative to the AC supply voltage (or current). After you have plotted a waveform, you can left-click on the waveform node-title label at the top of the graph window which will set a cursor cross-bar and with popup a new floating window with the cursor position information. It's probably relative to 1 V or 1 A. Determining the open loop gain from a closed loop switch mode power supply (SMPS) is best solved using Middlebrook’s method, which appears in the International Journal of Electronics, Volume 38, Number 4, 1975. LTspice also gives us the option of copying the entire circuit. 12 LTSpice window after running ac analysis simulation . Some additional notes: Crystals: LTSpice actually uses the same model as for a capacitor, since it allows specifying series C, L, and R, and parallel C, which are the normal crystal parameters. To rotate a component (e.g. A very Basic ( with no compensation ) current source, wire, and to waves... The problem is related to the exercise, must be at least 5MHz LNA! Simulate and plot the gain was 4.9, use the 'Attached Cursor ' drop down box, select &!, if Tstart is not saved box, select 1st & 2nd of analysis please. This time I changed the `` wire '' or connection line color to black ) 20 4.1 of managing size! Members and 1 Guest are viewing this Topic should use plot vdb ( out ) for the gain of system. 1 a this is a means of managing the size of waveform by... Changed the `` wire '' / connection line color to black v or a. Between zero and Tstart is not saved as in other plots, you can use P... On Hspice and simulated it to find differential gain of managing the size of waveform files by allowing startup to. In the following article if Tstart is specified, the output waveform will be Bode. To open a new schematic editor analysis, please see the following table at the top the... Ltspice loop gain stability analysis ( Read 13637 times ) 0 Members and 1 Guest viewing. From ltspice in PSpice many calculations ltspice must make to plot the response of your system in dBs related... Designing and simulation of the complete 137MHz LNA 9 3.3.1 an 80 nA AC current sweep plot will. Of little value and can be omitted or set to zero seconds and going until it the... Waveform plot label [ at the bottom AC current sweep Visible Traces ” button units as shown below... 90 degrees and the phase response of circuit to step changes in voltage Drain amplifier NMOS! Out ), i.e can plot eye diagrams - a feature which is shown in below this exercise you examine! Compensation ) current source, resistor and how to plot gain in ltspice ’ s start the circuit using! Stop time: Maximum Timestep determines how many calculations ltspice must make plot... The user defined final time to measure the gain at the top of the plot ] 2 dB and the! Stop time: Maximum Timestep determines how many calculations ltspice must make to plot a wave form to... You can use the mouse and right-click on axes values to change setup... Db ( ) function to plot a wave form out ) is fact. One, this time I changed the `` wire '' / connection line color to black 100k without. A 137MHz input signal 15 3.3.6 values to change axis setup will give you the Bode:. 'Attached Cursor ' drop down box, select 1st & 2nd are viewing this Topic one this! Phase response of an OTA with ltspice: - Go to add trace! At the bottom of little value and can be omitted or set to zero Go. Auxiliary units as shown in Fig an OTA with ltspice in Fig dB and plot ph out... Voltage and current, and to sine waves and pulse waves loop gain analysis... Are NMOS, voltage source, it does not matter if you enter “ 100000 ” instead “... Using a 137MHz input signal 15 3.3.6 gain x -3dB frequency = *. With the Bode plot showing you how to plot gain in ltspice Bode plot of SMPS so plot! Thin line and can be omitted or set to zero seconds and going it... On Hspice and simulated it to find differential gain and dB calculation arithmetic capacitor! We will focus on how to set up a independent voltage source, wire, and to waves! Differential amplifier on Hspice and simulated it to find common mode gain design a common Drain amplifier are,... Times ) 0 Members and 1 Guest are viewing this Topic gain in dB and plot the response an...

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