What is the Iout calculation for a BJT circuit with infinite gain?

In summary, the task is to calculate Iout for four BJTs with identical characteristics, β→∞, operating in forward active mode at the same temperature. With β→∞, IB for each BJT is zero, and IC=IE. The BJT exponential transfer characteristic equation, Ic=Is*e^(VBE/Vt), can be used to find Iout, but there is uncertainty on how to apply it. The final formula for Iout is I1*I2/I3, where ic1=I1, Vbe1 can be calculated using ic1 = is exp(Vbe1/VT), and this process can be repeated for each BJT until Vbe4 is found. Finally, using ic
  • #1
etf
179
2
Hi!
Here is my task:
Calculate Iout if all BJT's have identical characteristics with β→∞, work on same temperature in forward active mode. Use BJT exponential transfer characteristic.
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Since β→∞, IB for every BJT should be zero amps and IC=IE. Equation for BJT exponential transfer characteristic is Ic=Is*e^(VBE/Vt) but I don't know how to use it in order to find Iout. Any idea? Iout should be I1*I2/I3.
 
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  • #2
Using ic1 = is exp(Vbe1/VT), compute Vbe1. Note ic1 = I1.
Then using I2, compute Vbe2.
Etc. until you get to Vbe4. Finally, compute ic4 = Iout.
 
  • #3
Done. Thanks a lot!
 

1. What is a BJT circuit infinite gain?

A BJT (Bipolar Junction Transistor) circuit infinite gain refers to the condition where the gain of the BJT is extremely high, approaching infinity. This occurs when the input signal is amplified to the point where the output signal is significantly larger, resulting in an infinite gain.

2. How is the gain of a BJT circuit calculated?

The gain of a BJT circuit is calculated using the formula: gain = output voltage / input voltage. This is also known as the voltage gain. The current gain, or beta (β), is calculated using the formula: β = output current / input current.

3. What is the significance of infinite gain in BJT circuits?

Infinite gain in BJT circuits is significant because it allows for the amplification of weak signals to a level that can be easily detected and processed by other components in the circuit. This makes it a crucial component in many electronic devices and systems.

4. How can the gain of a BJT circuit be controlled?

The gain of a BJT circuit can be controlled by adjusting the biasing of the transistor. This can be done by changing the values of the resistors in the circuit, or by using a feedback circuit to regulate the gain.

5. What are some common applications of BJT circuits with infinite gain?

BJT circuits with infinite gain are commonly used in amplifiers, oscillators, and other electronic devices where weak signals need to be amplified. They are also used in signal processing and communication systems, such as radios and televisions.

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