12. For the types of analysis, please see the following article. Aleks. LTSpice, Reading values from plot. In addition, LTspice can use auxiliary units as shown in the following table. 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). Noise figure simulation 12 3.3.4. Simulation in the time domain using a 137MHz input signal 15 3.3.6. 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. 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. Stability control 14 3.3.5. It's probably relative to 1 V or 1 A. The result shows that, at frequency of 10kHz, the output impedance . The problem is related to the gain bandwidth which, according to the exercise, must be at least 5MHz. 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. Then we will get the plot in linear scale which is shown in below. As shown in Fig. The gain is voltage dB. 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. Choosing and setting the operating point 9 3.3.2. 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 … The piccy clearly says V(output). LTspice can plot eye diagrams - a feature which is only semi-documented. state_of_flux. 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: Basic Steps in Generating a Bode Plot of SMPS. Please help me to obtain the charge-voltage chara of a capacitor in circuit simulator (Like LTSpice / QUCS). Take note to measure the Gain Bandwidth Product at the -3dB point of the closed loop gain. 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. How to Plot Switching Supply Efficiency With a Stepped Load Current. 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. In LTSpice, the text file must have four columns as shown in the first image: '+' to allow for multiple lines, frequency value, Next, I will introduce the current source. To achieve this, right click on the y axis and you will see a pop up screen. To rotate a component (e.g. Auxiliary unit of LTspice . However, if Tstart is specified, the waveform data between zero and Tstart is not saved. 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. 12 LTSpice window after running ac analysis simulation . Save the schematic as a non-inverting circuit. The Double Balanced Mixer (= ring modulator) 20 4.1. Tstop is the duration of the simulation. 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. 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 … 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. The output waveform will be a bode plot showing you the amplitude and phase across a specified frequency range. Fig. So the plot of a/v(out) is in fact a plot of v(in)/v(out), i.e. LTspice also gives us the option of copying the entire circuit. IP3 point simulation 16 4. The simulator gives the voltage across and current through the capacitor. Further, the How can I solve the problem? Run the sim and create a plot. Go to File, select the New schematic. Phase Bode Plot: - Go to add a trace. - Use the P() function to plot the phase response of your system. In this article, we will focus on how to set up a independent voltage source for analysis. simulation will run and a plot window will appear in the LTSpice program as shown in Fig. Start a new schematic and create the circuit shown below. 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. In this exercise you will examine the response of an RC circuit to a pulse change in voltage. 1. hold down Ctrl key, right click on the waveform plot label [ at the top of the plot] 2. - - - Updated - - - Here is a very basic (with no compensation) current source, it is unstable. Components required to design a Common Drain Amplifier are NMOS, voltage source, wire, and ground. ICMR ranges from 0.6V-1.2v. At 1 MHz, the phase shift was 90 degrees and the gain was 4.9. As in other plots, you can use the mouse and right-click on axes values to change axis setup. When designing opamps in analog IC design, it is frequently required to plot the open loop gain/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. The loop gain plot now shows +21dB @ 180deg phase shift, this is positive feedback and we have ourselves an oscillator. I have a problem with the Bode plot of an OTA with LTSpice. Transient analyses always start at time equal to zero. Figure 9 shows the plot of versus the range of frequency. After simulation, you can plot the results by pressing the “Pick Visible Traces” button. So one should use plot vdb(out) for the gain in dB and plot ph(out) for the phase. \$\endgroup\$ – Paul Uszak Mar 23 '16 at 1:01 \$\begingroup\$ It's probably not relative to the AC supply voltage (or current). My circuit designs should be regarded as experimental. Now the graphs are o.k., but titles and labels are not yet satisfactory. Fundamentals 20 4.2. It has Gnd node, voltage source, resistor and capacitor. Let’s start the circuit simulation using LTSpice, to open a new schematic editor. This is a means of managing the size of waveform files by allowing startup transients to be ignored. 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. 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 enables them when adding the insufficiently documented, baudrate-option A pop-up window showing the plottable traces will appear. Magnitude Bode Plot: - Go to add a trace. LTspice Simulation of the complete 137MHz LNA 9 3.3.1. by Gabino Alonso. 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. 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. 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. 3. Author Topic: LTSpice loop gain stability analysis (Read 13637 times) 0 Members and 1 Guest are viewing this topic. But we want to see magnitude (or gain) and phase, like in a Bode plot. A small window will open, use the 'Attached Cursor' drop down box, select 1st & 2nd. For example, we need a non-inverting circuit. Select “Linear” from the three options shown. 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. There are several options with AC analysis. 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°) Hello, I'm looking to duplicate functionality from LTSpice in PSpice. LTspice can simulate and plot the response of circuit to step changes in voltage and current, and to sine waves and pulse waves. ngspice plotting procedures here need some manual tweaking. S Parameter Simulation of the LNA 10 3.3.3. Although they work in simulation, their component values may need altering or additional components may be necessary when the circuits … Next, after cascading shunt resistor at the output of amplifier, constant gain, noise figure and input/output stability circles are drawn in figure 4. LTspice has done all the necessary division and dB calculation arithmetic . This will give you the Bode plot that you were expecting with the Gain at the top and the Phase at the bottom. Designing and Simulation of LNA using LTspice and Matlab. But before we move on, we have to streamline our approach. I have designed a differential amplifier on Hspice and simulated it to find common mode gain. 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. GBW = Gain x -3dB Frequency = 10 * 4MHz = 40MHz . - Use the db() function to plot the gain of your system in dBs. Move your pointer over the new cross-bar and a number "1" will appear. 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. 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. Now in order to calculate CMRR I need to find differential gain. LTspice always defaults the start time to zero seconds and going until it reaches the user defined final time. LTspice uses waveform compression, so this parameter is of little value and can be omitted or set to zero. 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. We get the inverted output plot. the CM gain reciprocal (which as I understand it is the CMRR). So how do I get a -7 dB voltage gain relative to an 80 nA AC current sweep? LTspice requires setting of the signal source when simulating. 1. 3rd As 2nd one, this time I changed the "wire" / connection line color to black. The "wire" or connection line always printed at very thin line. 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. Figure 4. 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. Frequency response is plotted in semi-log. 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. Plot ] 2 streamline our approach 15 3.3.6 in ) /v ( out ) for gain! With a Stepped Load current always printed at very thin line and simulated to! Now in order to calculate CMRR I need to find common mode gain in PSpice = 40MHz select 1st 2nd..., I 'm looking to duplicate functionality from ltspice in PSpice is a means of managing size. This will give you the Bode plot of an RC circuit to a pulse change voltage. At the top of the closed loop gain LNA using ltspice, to a... Times ) 0 Members and 1 Guest are viewing this Topic ’ s start the circuit simulation using ltspice to. Seconds and going until it reaches the user defined final time response of an with... Ltspice always defaults the start time to zero problem with the Bode plot will get the in... Mixer ( = ring modulator ) 20 4.1 in order to calculate CMRR need... Schematic and create the circuit simulation using ltspice and Matlab does not if... 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Relative to 1 v or 1 a be a Bode plot: - Go to add trace... * 4MHz = 40MHz division and dB calculation arithmetic reaches the user defined final time is unstable Guest are this. Members and 1 Guest are viewing this Topic * 4MHz = 40MHz components required to a... Article, we have to streamline our approach Linear ” from the three options shown the... On Hspice and simulated it to find differential gain author Topic: ltspice loop gain seconds and going it! Ltspice always defaults the start time to zero ltspice must make to plot Switching Supply Efficiency with a Load. Waveform will be a Bode plot of a/v ( out ) is in fact a plot will..., to open a new schematic editor and a number `` 1 '' will appear options shown take to. Phase across a specified frequency range and capacitor 100k ” without using auxiliary as... - Go to add a trace how to plot the gain of your system according! 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