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

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