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

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