I am trying to size the Q1-Q0 current mirror pair so that the emitter area of Q0 is N time as large as that of Q1. Note: I have also looked into this post but it doesn't solve my problem. Am I missing something? You can probably tell by my comments that it is not clear to me what you are trying to do. But I just noticed that I failed to correctly read something you wrote:. But it is possible to read things differently, looking with fresh eyes at this.
And perhaps Mike directed you correctly in his comment. If you right-click on that symbol, you will see a dialog box that looks like:. You can do this differently for each and every one you put on the schematic, so there is no requirement at all that they be the same.
To begin, you will see something like the following if you do it correctly:. You can also control-right-click on the symbol and you will see, under "Value", a designation there that you can now edit. If you choose this method, the display will look something like:. Either approach works. The main thing is to change this name to something that isn't found anywhere else. Make up a name.
The output is typically measured in a range of milliamps. Also, a contributing factor is the current gain called beta. There is another factor called alpha, but can be calculated from beta by:. Beta values are typically listed in the datasheet of bipolar transistors. The values above are important to circuit designs with transistors involved.
Make sure to rotate the component so that the arrow is facing up, as that is the current direction we want. The values of the resistor on the left of the circuit k and k are for reducing input current to microAmpere levels.
The input current is connected to the base leg of the NPN transistor. This will bring up the list of all the models the program installs with by default quite a bit to use just for transistors. In this case, we are only interested in the beta factor as that is a main key factor in a bipolar transistor.
To obtain the same output characteristic on the virtual O-Scope, a special simulation must be used. The DC Sweep will be used to sweep both of our sources: the input voltage V1 and the input current source I1. The DC voltage is typically swept in a smooth linear fashion while the current source is stepped with significant micro amp stages. To achieve this, click run and swap to the DC Sweep tab and edit the first source as seen here: V1 is the source we sweep, we are using linear interpolation, start at 0V, end at 16V can be any number of preferenceand increment each 0.
This will create a smooth linear input voltage rise. Then click the 2nd Source tab to edit the values for the current source I1: The second source is stepped in significant stages with linear interpolation. Begin with 0A and end with somewhere around uA can be more or less, depends on transistor choice and beta value, that is why experimentation works best with this method. Use an increment value of 10uA steps or anything beneath uA. Smaller steps will take longer for it to simulate but will be more accurate.
Larger steps will take less time, but will not be a good representation of data. Click OK and there are a few places to consider measuring for experimentation. Specifically for getting the same graph as I mentioned before, probe the current on the leg where the 1k ohm line goes into the transistor the collector.
A special symbol will show up if one hovers over the leg. Here is the output I get with a beta factor of 50 on a 2N transistor with the default setup: OutputCharGraphuA. After 10V for the top orange linethe output does gradually increase current, but not significantly.
The measurement from when it levels off around 10V to the full 16 volts is only a This is pretty useful information with certain designs. This is expected because beta is held to be a constant value, so the graph is reasonable for the changing input current versus changing input voltage. All Rights Reserved. Continue Continue Privacy Notice.Remember Me? How to change transistor parameters in PSpice? Last edited by aisd; 15th January at Re: How to change transistor parameters in PSpice? Hi I use Orcad capture but I think this will work on pspice too, Right click on transistor or any other electronic component and choose Edit Pspice model there you can find its Spice model parameters and you can change them.
Originally Posted by hamidmoallemi.
Did you choose "edit instant model"? I never have experienced problems in that case. Originally Posted by LvW. Originally Posted by aisd. How to change hspice parameters to pspice parameters? How can I change the transistor size in Pspice 0. Part and Inventory Search. Welcome to EDABoard. Design Resources. New Posts. PSS does not converg 1. High voltage inverter problem 1. CMFB amplifier with cascoded diode load 1.
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Recently Updated Groups. Top Experience Points. EE World Online. Design Fast. The time now is All rights reserved.Spice is a program developed by the EE Department at the University of California at Berkeley for computer simulation of analog circuits. In its original form you tell Spice what elements are in the circuit resistors, capacitors, etc.
Every node is assigned a number, and there is always a ground node, which is Number 0. Several companies have developed graphical user interfaces for Spice, which make it much easier to use. One of the most popular is PSpice. PSpice provides a free student version of its program which can be downloaded from www. When you start up you will get a screen which looks like this:.
To put in a component, use the Draw drop-down menu, and select Get new part or use the shortcut Ctrl-G. This will bring up a dialog box which will allow you to select pats from libraries.
If the part you want is not on the list, try another library — parts such as transistors will probably be in eval. Select the part you want and place it on the schematic:. Continue placing the components you need. If need a component of the same type as one you have already placed, you can use the Draw — Place Part Ctrl-P shortcut.
SPICE - A Brief Tutorial
You can rotate an object by clicking on it to highlight it, then use Edit — Rotate or Ctrl-R. You can change the value of a component by double-clicking on the component value, and entering a new value. You can connect components together by placing wires — Draw — Wire or Ctrl-W.
Be sure to place an analog ground AGND. When done you will have something which looks like this:. Be sure to save the file, then go to Analysis — Setup. Here you will tell PSpice what you want it to do. Always select Bias Point Detail. In this case we will also select AC Sweep which will give the frequency response of the circuit.
Click on AC Sweep to tell what frequency range you want to use:. Here we will cover the frequencies from Hz to 1 MHz. If you use M, PSpice will interpret this as milli 10 Now choose Analysis — Simulate and PSpice will run, and pop up an analysis window:.The description is far from complete, as SPICE is a powerful circuit simulator with many capabilities.
However, this document will serve as a start for students in introductory classes. For more information, please refer to the SPICE user's manual or books listed at the end of the document. The translated versions: Slovak Language can be found here. Table of Contents A. This is of particular importance for integrated circuits.
A complete manual of the Avant! SPICE can do several types of circuit analyses. Non-linear transient analysis: calculates the voltage and current as a function of time when a large signal is applied. Linear AC Analysis: calculates the output as a function of frequency. A bode plot is generated. Noise analysis Sensitivity analysis Distortion analysis Fourier analysis: calculates and plots the frequency spectrum.
This makes it a useful tool for a wide range of analog and digital applications. All analyses can be done at different temperatures.
The default temperature is K. Data statements : description of the components and the interconnections. Output statements : specifies what outputs are to be printed or plotted. Although these statements may appear in any order, it is recommended that they be given in the above sequence. Two other statements are required: the title statement and the end statement.
The title statement is the first line and can contain any information, while the end statement is always. This statement must be a line be itself, followed by a carriage return! Numbers can be integers, or floating points. Spice uses the node-voltage analysis. It solves for the unknown node voltages and also the unknown currents through independent voltage sources.
This gives us a way to find currents flowing in elements: one has to ask for the current through a voltage source. Some versions of PSpice allow you to ask for a current through a resistor without using a voltage source EX: I R1 gives the current in the resistor R1.
NC1 and NC2 are the positive and negative terminals of the controlling voltage source, respectively. Vcontrol is the zero value voltage source used to measure the controlling current the positive current flows into the positive terminal of the controlling voltage source!
Examples: F1 0 3 Vmeas 0. Resistors Rname N1 N2 Value d. N2 is the negative node. IC is the initial condition DC voltage or current. If not specified, it is assumed to be zero. In case of an inductor, the current flows from N1 to N2. OP DC Statement. DC Transfer Function.
Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It only takes a minute to sign up. I'm having trouble every time I need to find a component with Ltspice. Normally I manage to find what I need but not for the current component.
I need a 2n transistor. I've tried to enter words in the component search toolbar for transistor, nothing. I tried to enter the code, nothing. I wonder what is the best way when you know the component you need to search it, because every time I need a new one, it ends up being troubles.ORCAD - Common Emitter Configuration: Input/Output Characteristics Curve of a Transistor (BJT)
For standard components like transistors, diodes, inductors and capacitors the selectable components are not inside the component placement tool, but in a separate dialog. So you select your standard component npn transistor in this case and place it on your schematic. After that "rightclick" it. A window opens with general information about the part. It also contains a button labelled "Pick new transistor".
Click that button and you end up with this:. The library of parts is only that large - it doesn't contain everything you need because it would have to contain everything, as I need other stuff than you do.
So one skill you'll eventually have to learn is how to include a not supplied model into LT-Spice. When you're in the drawing editor, left click on the "GET" icon on the menu bar it looks like an AND gate and it's right between the diode and the open hand and a dialog will pop up. Mouse over to where you want it to be and left click once again to place it. Now, if you right-click on the NPN, a dialog box will appear. Sign up to join this community. The best answers are voted up and rise to the top.
Home Questions Tags Users Unanswered. Ask Question. Asked 4 years, 5 months ago. Active 4 years, 5 months ago. Viewed 17k times. I tried to enter the code, nothing I wonder what is the best way when you know the component you need to search it, because every time I need a new one, it ends up being troubles. Cher Cher 3 3 gold badges 4 4 silver badges 10 10 bronze badges. Active Oldest Votes. Click that button and you end up with this: You can sort by part number or other parameters.
I have included as much information as possible, so it should just be a matter of pointing out something simple hopefully. I am running a Transient Analysis on the circuit and am receiving the following simulation results attached imageswhich I am having trouble interpreting.
I have also listed my minimum specs for the circuit and my theoretically computed values. As far as I can tell, I am doing everything correctly, although I am not seeing how to choose the Collector Resistance since it does not appear in any of my equations. Ground, or a fixed voltage relative to it.
Larger values will still work, but with reduced output voltage swing. In your circuit the Emitter can only go up to slightly less than 9V, because RC is then dropping 1V so the transistor is saturated approaching zero volts between Collector and Emitter.
Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Asked 5 years, 4 months ago. Active 5 years, 4 months ago. Viewed 4k times. Null 5, 10 10 gold badges 23 23 silver badges 34 34 bronze badges.
But then why include it? Surely it must affect something. But these voltages we desire conflict with my understanding that the voltage across Rc is determine by the voltage bias across R1.
How does this all come together? This may its own question Active Oldest Votes. Bruce Abbott Bruce Abbott I'm not sure if you are familiar with PSPICE, but if you are: can you please point out on my Waveform and Cursor images where the Voltage gain can be observed, and where the Q-point is listed in the simulation Output File? The simulation results seem to indicate the voltages only for DC analysis, with capacitors as open. I have trying running an AC Sweep, but this creates more problems an is not how I am supposed to do this.
Transient analysis shows the instantaneous voltages vs time.
Only AC analysis calculates signal amplitudes.