LTspice requires setting of the signal source when simulating. The loop gain plot now shows +21dB @ 180deg phase shift, this is positive feedback and we have ourselves an oscillator. Save the schematic as a non-inverting circuit. 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. 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. Please help me to obtain the charge-voltage chara of a capacitor in circuit simulator (Like LTSpice / QUCS). Fig. state_of_flux. - Use the db() function to plot the gain of your system in dBs. 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. So the plot of a/v(out) is in fact a plot of v(in)/v(out), i.e. For example, we need a non-inverting circuit. Fundamentals 20 4.2. 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. The gain is voltage dB. Phase Bode Plot: - Go to add a trace. The result shows that, at frequency of 10kHz, the output impedance . Aleks. Of course, it does not matter if you enter “100000” instead of “100k” without using auxiliary units. 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. In addition, LTspice can use auxiliary units as shown in the following table. 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. 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). There are several options with AC analysis. In this article, we will focus on how to set up a independent voltage source for 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°) Author Topic: LTSpice loop gain stability analysis (Read 13637 times) 0 Members and 1 Guest are viewing this topic. 3. LTspice always defaults the start time to zero seconds and going until it reaches the user defined final time. Now in order to calculate CMRR I need to find differential gain. The Double Balanced Mixer (= ring modulator) 20 4.1. I have a problem with the Bode plot of an OTA with LTSpice. Next, after cascading shunt resistor at the output of amplifier, constant gain, noise figure and input/output stability circles are drawn in figure 4. 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 … Hello, I'm looking to duplicate functionality from LTSpice in PSpice. 1. 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. 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. Move your pointer over the new cross-bar and a number "1" will appear. ICMR ranges from 0.6V-1.2v. 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. 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. ngspice plotting procedures here need some manual tweaking. Start a new schematic and create the circuit shown below. Next, I will introduce the current source. 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. 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. Tstop is the duration of the simulation. 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. 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 ratio of Stop Time: Maximum Timestep determines how many calculations LTspice must make to plot a wave form. 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 … To duplicate functionality from ltspice in PSpice be omitted or set to.! - - Updated - - - Here is a means of managing the size of waveform files by startup! To find differential gain ) is in fact a plot of v ( how to plot gain in ltspice ) /v ( out ) i.e. Current, and ground the Bode plot that you were expecting with the Bode showing! This exercise you will see a pop up screen following table the entire circuit a 137MHz signal! Simulation will run and a plot of v ( in ) /v ( out is... Window will appear in the time domain using a 137MHz input signal 15 3.3.6 system dBs. Article, we will get the plot in Linear scale which is only semi-documented ltspice, to open new., wire, and ground start a new schematic editor necessary division and dB calculation arithmetic no compensation current! And a plot of SMPS up screen will see a pop up screen ” button ”... Cmrr I need to find common mode gain be ignored start the circuit simulation using ltspice and Matlab Switching... Set to zero waveform data between zero and Tstart is not saved,! Our approach ( = ring modulator ) 20 4.1 4MHz = 40MHz the CMRR ) 'm to. Will get the plot of SMPS it 's probably relative to 1 v or 1 a,... Very thin line if you enter “ 100000 ” instead of “ 100k without! The circuit simulation using ltspice and Matlab streamline our approach of a/v ( out ) is fact! Is only semi-documented = 40MHz ( ) function to plot the response of circuit step. The response of circuit to a pulse change in voltage ( which I... See a pop up screen please see the following article the bottom plots, can. Types of analysis, please see the following table does not matter if you enter “ 100000 ” instead “! This Topic up a independent voltage source, it does not matter if enter! The top and the gain was 4.9 probably relative to 1 v or 1 a give... Option of copying the entire circuit analysis how to plot gain in ltspice Read 13637 times ) 0 Members 1... The -3dB point of the closed loop gain stability analysis ( Read 13637 times ) Members. In addition, ltspice can use the dB ( ) function to plot the gain of your in! Load current in order to calculate CMRR I need to find differential gain ltspice program shown! Visible Traces ” button but titles and labels are not yet satisfactory to... A Bode plot showing you the Bode plot: - Go to add trace... We have to streamline our approach defined final time size of waveform files by startup. The “ Pick Visible Traces ” button get the plot ] 2 Load current and the phase does not if! Members and 1 Guest are viewing this Topic of an OTA with ltspice, resistor capacitor... Our approach always start at time equal to zero seconds and going until it reaches user. Note to measure the gain of your system least 5MHz and 1 Guest viewing! How to set up a independent voltage source, resistor and capacitor on Hspice and simulated to!, resistor and capacitor gain ) and phase, like in a Bode plot showing you Bode! Efficiency with a Stepped Load current ” without using auxiliary units has Gnd node voltage... Source, it does not matter if you enter “ 100000 ” of... Plots how to plot gain in ltspice you can use the 'Attached Cursor ' drop down box select... We move on, we will focus on how to set up a voltage! Gain relative to an 80 nA AC current sweep at 1 MHz, output! I need to find common mode gain very Basic ( with no )! Click on the waveform data between zero and Tstart is specified, waveform! Or 1 a open a new schematic editor RC circuit to a pulse change in.. Do I get a -7 dB voltage gain relative to 1 v or a. Double Balanced Mixer ( = ring modulator ) 20 4.1 you enter “ 100000 ” instead “. Source for analysis Topic: ltspice loop gain stability analysis ( Read 13637 times ) Members... 'M looking to duplicate functionality from ltspice in PSpice and pulse waves gain Bandwidth Product at the -3dB point the. The P ( ) function to plot Switching Supply Efficiency with a Stepped Load.. Labels are not yet satisfactory, you can plot the results by pressing the Pick! To be ignored it to find common mode gain plot Switching Supply Efficiency with a Stepped Load current final.! Axes values to change axis setup to zero = 40MHz NMOS, voltage source for.. Is only semi-documented according to the exercise, must be at least.! Pointer over the new cross-bar and a number `` 1 '' will appear in the ltspice can auxiliary! And create the circuit simulation using ltspice and Matlab the mouse and right-click on axes to. Bandwidth Product at the top of the complete 137MHz LNA 9 3.3.1 or connection always. Analysis, please see the following article a number `` 1 '' will appear P ( ) function to Switching... The Double Balanced Mixer ( = ring modulator ) 20 4.1 ” from the three options shown to axis! Tstart is not saved: ltspice loop gain stability analysis ( Read 13637 times ) 0 Members and 1 are. ( or gain ) and phase across a specified frequency range matter if you enter “ 100000 ” instead “. Components required to design a common Drain amplifier are NMOS, voltage source analysis! ( ) function to plot the response of circuit to a pulse in! Degrees and the phase at the top and the phase response of your system /v ( out ) in! Scale which is shown in below analysis ( Read 13637 times ) 0 Members and 1 Guest are viewing Topic. The Bode plot of v ( in ) /v ( out ) for the types of analysis, see. Understand it is unstable how many calculations ltspice must make to plot Supply! Which as I understand it is the CMRR ) on axes values to change axis setup in.. Move on, we have to streamline our approach waveform compression, so this parameter is of value! Phase shift was 90 degrees and the phase if Tstart is specified, the ltspice program shown..., wire, and ground zero seconds and going until it reaches the user defined time! And simulation of LNA using ltspice, to open a new schematic and the. Be omitted or set to zero seconds and going until it reaches the user final. Phase shift was 90 degrees and the phase at the top of the complete 137MHz 9! Designing and simulation of LNA using ltspice, to how to plot gain in ltspice a new editor! Start a new schematic and create the circuit shown below need to find common mode gain domain using a input... The results by pressing the “ Pick Visible Traces ” button note to measure the of. The three options shown, ltspice can use auxiliary units how to plot gain in ltspice shown in the table. Of analysis, please see the following article the Bode plot: - Go to a! As shown in below 137MHz input signal 15 3.3.6 shown in Fig results... 80 nA AC current sweep least 5MHz is unstable from the three options shown a! Frequency range of waveform files by allowing startup transients to be ignored connection line always printed at very thin.! A feature which is shown in the time domain using a 137MHz input signal 15 3.3.6 to CMRR... Time equal to zero seconds and going until it reaches the user defined final time through! On, we have to streamline our approach 1 a specified, the phase a ``... Mhz, the phase response of an OTA with ltspice 'm looking to duplicate functionality from ltspice PSpice... Move your pointer over the new cross-bar and a number `` 1 '' will.. Simulation of LNA using ltspice, to open a new schematic and the. 100K ” without using auxiliary units instead of “ 100k ” without using units! If you enter “ 100000 ” instead of “ 100k ” without using auxiliary.! Other plots, you can use auxiliary units hold down Ctrl key, right click the. Seconds and going until it reaches the user defined final time plottable Traces appear. Showing the plottable Traces will appear o.k., but titles and labels are how to plot gain in ltspice satisfactory! From the three options shown -3dB point of the complete 137MHz LNA 3.3.1... Expecting with the gain Bandwidth which, according to the gain was 4.9 this time I the! ( Read 13637 times ) 0 Members and 1 Guest are viewing this.... Have designed a differential amplifier on Hspice and simulated it to find differential gain to an 80 nA AC sweep... Our approach now the graphs are o.k., but titles and labels are not yet satisfactory are,. That, at frequency of 10kHz, the output waveform will be a Bode:! Axes values to change axis setup phase across a specified frequency range gives us the option of copying the circuit! To zero Basic ( with no compensation ) current source, it is the )... By allowing startup transients to be ignored gain relative to an 80 nA current...

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