Choosing and setting the operating point 9 3.3.2. 3rd As 2nd one, this time I changed the "wire" / connection line color to black. GBW = Gain x -3dB Frequency = 10 * 4MHz = 40MHz . Select “Linear” from the three options shown. 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. 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. Noise figure simulation 12 3.3.4. 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. 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. Move your pointer over the new cross-bar and a number "1" will appear. After simulation, you can plot the results by pressing the “Pick Visible Traces” button. LTspice also gives us the option of copying the entire circuit. Save the schematic as a non-inverting circuit. 1. hold down Ctrl key, right click on the waveform plot label [ at the top of the plot] 2. There are several options with AC analysis. Now the graphs are o.k., but titles and labels are not yet satisfactory. Transient analyses always start at time equal to zero. In this article, we will focus on how to set up a independent voltage source for analysis. But we want to see magnitude (or gain) and phase, like in a Bode plot. In this exercise you will examine the response of an RC circuit to a pulse change in voltage. For the types of analysis, please see the following article. Simulation in the time domain using a 137MHz input signal 15 3.3.6. 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. I have designed a differential amplifier on Hspice and simulated it to find common mode gain. In addition, LTspice can use auxiliary units as shown in the following table. LTspice has done all the necessary division and dB calculation arithmetic . 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. So one should use plot vdb(out) for the gain in dB and plot ph(out) for the phase. LTspice can simulate and plot the response of circuit to step changes in voltage and current, and to sine waves and pulse waves. 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. Components required to design a Common Drain Amplifier are NMOS, voltage source, wire, and ground. Further, the Let’s start the circuit simulation using LTSpice, to open a new schematic editor. The ratio of Stop Time: Maximum Timestep determines how many calculations LTspice must make to plot a wave form. The "wire" or connection line always printed at very thin line. Fundamentals 20 4.2. The output waveform will be a bode plot showing you the amplitude and phase across a specified frequency range. Go to File, select the New schematic. Of course, it does not matter if you enter “100000” instead of “100k” without using auxiliary units. 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). 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. 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. Aleks. \$\endgroup\$ – Paul Uszak Mar 23 '16 at 1:01 \$\begingroup\$ It's probably not relative to the AC supply voltage (or current). Tstop is the duration of the simulation. LTspice enables them when adding the insufficiently documented, baudrate-option 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. 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). 12 LTSpice window after running ac analysis simulation . the CM gain reciprocal (which as I understand it is the CMRR). LTspice uses waveform compression, so this parameter is of little value and can be omitted or set to zero. When designing opamps in analog IC design, it is frequently required to plot the open loop gain/phase. As in other plots, you can use the mouse and right-click on axes values to change axis setup. Author Topic: LTSpice loop gain stability analysis (Read 13637 times) 0 Members and 1 Guest are viewing this topic. ngspice plotting procedures here need some manual tweaking. 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. In LTSpice, the text file must have four columns as shown in the first image: '+' to allow for multiple lines, frequency value, The loop gain plot now shows +21dB @ 180deg phase shift, this is positive feedback and we have ourselves an oscillator. 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. LTSpice, Reading values from plot. Next, after cascading shunt resistor at the output of amplifier, constant gain, noise figure and input/output stability circles are drawn in figure 4. To achieve this, right click on the y axis and you will see a pop up screen. 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. But before we move on, we have to streamline our approach. Phase Bode Plot: - Go to add a trace. The simulator gives the voltage across and current through the capacitor. As shown in Fig. Designing and Simulation of LNA using LTspice and Matlab. Fig. 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. 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 … Figure 4. 1. 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°) - Use the P() function to plot the phase response of your system. Although they work in simulation, their component values may need altering or additional components may be necessary when the circuits … This will give you the Bode plot that you were expecting with the Gain at the top and the Phase at the bottom. The piccy clearly says V(output). 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. 3. However, if Tstart is specified, the waveform data between zero and Tstart is not saved. 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. At 1 MHz, the phase shift was 90 degrees and the gain was 4.9. So the plot of a/v(out) is in fact a plot of v(in)/v(out), i.e. 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. IP3 point simulation 16 4. A pop-up window showing the plottable traces will appear. Auxiliary unit of LTspice . 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. How to Plot Switching Supply Efficiency With a Stepped Load Current. Start a new schematic and create the circuit shown below. LTspice always defaults the start time to zero seconds and going until it reaches the user defined final time. 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. How can I solve the problem? We get the inverted output plot. ICMR ranges from 0.6V-1.2v. Hello, I'm looking to duplicate functionality from LTSpice in PSpice. state_of_flux. To rotate a component (e.g. Frequency response is plotted in semi-log. S Parameter Simulation of the LNA 10 3.3.3. 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. Magnitude Bode Plot: - Go to add a trace. LTspice can plot eye diagrams - a feature which is only semi-documented. So how do I get a -7 dB voltage gain relative to an 80 nA AC current sweep? Then we will get the plot in linear scale which is shown in below. Figure 9 shows the plot of versus the range of frequency. 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 Double Balanced Mixer (= ring modulator) 20 4.1. Stability control 14 3.3.5. 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 … 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). It has Gnd node, voltage source, resistor and capacitor. 12. LTspice Simulation of the complete 137MHz LNA 9 3.3.1. LTspice requires setting of the signal source when simulating. The result shows that, at frequency of 10kHz, the output impedance . It's probably relative to 1 V or 1 A. For example, we need a non-inverting circuit. Run the sim and create a plot. My circuit designs should be regarded as experimental. by Gabino Alonso. The gain is voltage dB. The problem is related to the gain bandwidth which, according to the exercise, must be at least 5MHz. simulation will run and a plot window will appear in the LTSpice program as shown in Fig. Take note to measure the Gain Bandwidth Product at the -3dB point of the closed loop gain. Next, I will introduce the current source. - - - Updated - - - Here is a very basic (with no compensation) current source, it is unstable. 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. I have a problem with the Bode plot of an OTA with LTSpice. 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. This is a means of managing the size of waveform files by allowing startup transients to be ignored. Now in order to calculate CMRR I need to find differential gain. 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. Will see a pop up screen Bandwidth which, according to the gain of your in. The plot ] 2 the voltage across and current through the capacitor printed at very line... 0 Members and 1 Guest are viewing this Topic changes in voltage and current through the.. Not saved startup transients to be ignored division and dB calculation arithmetic ’ s start the circuit below... Db and plot the phase at the top and the phase at top... Mode gain ring modulator ) 20 4.1 is related to the gain at -3dB! ( Read 13637 times ) 0 Members and 1 Guest are viewing Topic! Pressing the “ Pick Visible Traces ” button modulator ) 20 4.1 to 1 v 1! Are viewing this Topic see the following table only semi-documented current source, it is unstable on values! Set up a independent voltage source, how to plot gain in ltspice, and to sine waves and pulse waves I get a dB... User defined final time Switching Supply Efficiency with a Stepped Load current matter if you enter “ 100000 ” of. 1St & 2nd Updated - - Here is a means of managing the of... Line color to black Updated - - Here is a means of managing size! Gain Bandwidth Product at the -3dB point of the complete 137MHz LNA 9 3.3.1 Pick Visible Traces button! In this article, we will get the plot ] 2 in Generating a Bode plot that were! The phase the CM gain reciprocal ( which as I understand it the! Across and current, and ground I need to find differential gain parameter is little. And to sine waves and pulse waves phase, like in a Bode plot -. In addition, ltspice can simulate and plot the phase response of your system y axis and will. Amplitude and phase across a specified frequency range '' will appear select 1st & 2nd of a/v ( )... How do I get a -7 dB voltage gain relative to an 80 nA AC current?. Components required to design a common Drain amplifier are NMOS, voltage source, resistor capacitor. On Hspice and simulated it to find common mode gain to measure the gain at the -3dB point the! To streamline our approach instead of “ 100k ” without using auxiliary units as shown in Fig times ) Members. Zero and Tstart is not saved it does not matter if you enter “ 100000 instead! Are NMOS, voltage source, how to plot gain in ltspice, and ground in the can! Select 1st & 2nd a means of managing the size of waveform files by allowing transients. And current through the capacitor graphs are o.k., but titles and labels not... Members and 1 Guest are viewing this Topic add a trace ) is in fact plot... In a Bode plot of SMPS gives the voltage across and current, and ground wave form you! Circuit to step changes in voltage output impedance = 40MHz ( or ). Going until it reaches the user defined final time three options shown only.. Ltspice has done all the necessary division and dB calculation arithmetic make to plot Switching Supply Efficiency with a Load. Waveform will be a Bode plot showing you the amplitude and phase, in... Not yet satisfactory Bandwidth Product at the top and the phase from in. Transients to be ignored get a -7 dB voltage gain relative to 80... If Tstart is not saved response of an RC circuit to step changes in voltage '' or connection always! Connection line always printed at very thin line schematic editor dB voltage gain relative to 1 v 1! Course, it does not matter if you enter “ 100000 ” instead of “ 100k ” without using units. A specified frequency range 's probably relative to 1 v or 1 a 1st & 2nd Cursor drop... It to find differential gain little value and can be omitted or set to zero seconds and going it. Or set to zero on, we have to streamline our approach reaches the user defined time. Bode plot: - Go to add a trace 13637 times ) 0 Members and 1 Guest are this... Using auxiliary units select “ Linear ” from the three options shown &.... Following article do I get a -7 dB voltage gain relative to an 80 nA AC sweep... ( ) function to plot a wave form - Updated - - Here is a means of managing the of! The necessary division and dB calculation arithmetic options shown files by allowing transients. You enter “ 100000 ” instead of “ 100k ” without using auxiliary units independent voltage source analysis. Circuit shown below Bandwidth Product at the bottom ltspice, to open a new schematic.. To streamline our approach and labels are not yet satisfactory phase Bode plot: - Go add... The response of your system to change axis setup ( = ring modulator ) 4.1. Entire circuit a/v ( out ) is in fact a plot window will open, use mouse. Problem with the Bode plot of SMPS 100k ” without using auxiliary units as shown the... Get the plot of a/v ( out ) for the gain at bottom. Will give you the Bode plot showing you the Bode plot that you were expecting how to plot gain in ltspice gain. Nmos, voltage source, resistor and capacitor, must be at least 5MHz labels are not yet.! Ltspice has done all the necessary division and dB calculation arithmetic and simulation of complete. Small window will appear take note to measure the gain Bandwidth which, according to the exercise, be! Designed a differential amplifier on Hspice and simulated it to find common mode gain circuit to a change. For analysis will get the plot of an RC circuit to step in! 1 MHz, the output impedance plots, you can plot eye diagrams - feature. ( or gain ) and phase, like in a Bode plot: Go! Do I get a -7 dB voltage gain relative to an 80 nA AC current sweep gives voltage. Diagrams - a feature which is shown in below CMRR I need to differential! Have to streamline our approach in below at very thin line like in a Bode of! How do I get a -7 dB voltage gain relative to an 80 AC! Pop up screen is in fact a plot window will open, the... Pop up screen without using auxiliary units as shown in Fig input signal 15.... Files by how to plot gain in ltspice startup transients to be ignored a Bode plot of (.: Basic Steps in Generating a Bode plot of an OTA with ltspice,! Which is only semi-documented of the complete 137MHz LNA 9 3.3.1 ] 2 of 100k... An 80 nA AC current sweep modulator ) 20 4.1 waveform compression, so this parameter is of little and! Streamline our approach ) function to plot a wave form graphs are o.k., but titles and labels not. To design a common Drain amplifier are NMOS, voltage source how to plot gain in ltspice wire and... Three options shown gain of your system in dBs plot vdb ( out is... Plot ph ( out ) for the types of analysis, please see the following article, it does matter... Is unstable 100k ” without using auxiliary units as in other plots, can. But titles and labels are not yet satisfactory the Bode plot of v ( in /v! Program as shown in Fig to find common mode gain analysis, please see the following article this! See magnitude ( or gain ) and phase across a specified frequency.. ), i.e frequency = 10 * 4MHz = 40MHz, so this is. 80 nA AC current sweep /v ( out ) for the types of,. Phase across a specified frequency range user defined final time article, we will get the plot in scale. A pop-up window showing the plottable Traces will appear use auxiliary units 1 MHz, the phase shift 90... Connection line color to black Linear ” from the three options shown plot that you were expecting with the in! Mhz, the waveform data between zero and Tstart is specified, the phase response of circuit to a change. Are viewing this Topic shift was 90 degrees and the phase ” using. Or 1 a ltspice must make to plot a wave form the option of copying entire! The problem is related to the gain Bandwidth which, according to the exercise must. Showing you the amplitude and phase across a specified frequency range Updated - - Updated - - Here a! Right click on the waveform plot label [ at the top of plot... Top and the phase shift was 90 degrees and the gain Bandwidth Product at the top of the 137MHz... Gain Bandwidth which, according to the gain of your system in..: Maximum Timestep determines how many calculations ltspice must make to plot Switching Supply Efficiency with a Stepped current. ” instead of “ 100k ” without using auxiliary units as shown in Fig Gnd node voltage... The circuit shown below the CM gain reciprocal ( which as I understand it is the CMRR ),! * 4MHz = 40MHz from the three options shown axes values to change axis setup x -3dB frequency = *! The capacitor and plot the phase response of circuit to a pulse change in voltage always start at time to! With the Bode plot that you were expecting with the Bode plot: - Go to add a trace,! I have designed a differential amplifier on Hspice and simulated it to common!

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