05-12-2012 01:59 AM
How can I use NI ELVIS IMPEDANCE ANALYZER to measure input and output impedance of a BJT circuit.
My circuit to be analyzed is as shown in my attachment.
05-12-2012 09:39 AM
Posting the same question multiple times and minutes apart is not the best method to get your question answered. It is more likely that you will just irritate people.
05-12-2012 04:21 PM
I do not have any idea about the capabilities of ELVIS.
1. How would you measure the input and output impedances of this circuit if you used physical laboratory equipment? Do something similar.
2. The impedances of the circuit you have drawn are strongly dependent on the amplitude of the signal from the function generator. How do you plan to report or specify the operating regions?
3. What have you tried? What worked or did not work? Did you get any errors?
4. If this is a school assignment, do not expect someone on the Forum to do your work for you. It would be unethical and you would not learn anything.
Lynn
05-13-2012 01:24 AM
I started with measuring the impedance of LCR circuit and actually am able to analyze it My problem is on how I can use the impedance analyzer to determine input and output impedance of a circuit.
I have tried several times to connect the DUT+ to the input of my BJT circuit and the DUT- to emitter terminal, the results obtained were in terms of MegaOhms while in reality should be in KiloOhms.
05-13-2012 11:47 AM
As I mentioned earlier, the input impedance of the circuit depends on the input voltage. For instantaneous voltages less than about 0.6 V the base-emitter junction does not conduct and the effective input impedance will be high. At higher voltages the circuit will draw base current and the input impedance will be somewhat larger than the base resistor. Similarly the toutput impedance will vary with the operating point.
To effectively measure the input and output impedances of a circuit like this, you need be able to separate the operating point bias currents and voltages from the small signal, time varying portions.
Lynn