how to plot gain in ltspice

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

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