how to plot gain in ltspice

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

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