No.The gain is highly dependent on the Beta of the transistors.
I might agree with you but I have never tried an unbiased photodiode without a DC load. I think the coupling capacitor will become charged by the tiny "solar cell" and stay charged without passing the signal. It will work if the photodiode has a DC load then the coupling capacitor can charge and discharge and pass an AC signal.I also question your photodiode connection - especially the fact that DC is blocked. Photodiodes are not bidirectional devices. You should DC couple them to the first stage.
No.
The voltage gain of a transistor has nothing to do with its Beta. Beta controls its current gain, not its voltage gain. Voltage gain is simply VRC/VRe where VRe is the transistor's internal emitter resistance.
Nope.Re is highly dependent on Beta; therefore the voltage gain is highly dependent on Beta.
OK, I see now. But while it is technically correct to say that voltage gain does not depend on Beta, I don't think this voltage gain, as such, is the relevant parameter in assessing the performance of the OP's circuit. Here is why. The output voltage of the Q3 stage is directly proportional to collector current. And Beta is collector current divided by base current. So in this circuit, Beta determines output voltage as a function of base current, while voltage gain is output voltage as a function of base voltage. The distinction between voltage gain and Beta is equivalent to the distinction between base voltage and base voltage. So if we changed transistors to get a higher voltage gain, but kept the same Beta, that could only mean that the new transistor draws more base current for the same base voltage. (I am referring to AC voltages and currents throughout.) That is fine if the circuit driving the amplifier is very low impedance. It would be able to supply the same voltage regardless of how much current is drawn. But in the OP's circuit, the Q3 stage is driven by a stage with an output impedance of 2.7 K and the Q2 stage is driven by 47 K. These driving impedances mean that the base voltage is not independent of the voltage gain of the transistor. In fact it could be more like driving with a constant current than a constant voltage. Therefore current gain, and not voltage gain, is what will determine the final output voltage of the whole 3-transistor circuit for a given signal at the photodiode. And I assume that that is what the OP wants to know the voltage gain for. So I still say that using transistors with a higher Beta is the best way to get the highest signal out of this circuit, even if voltage gain on a stage by stage basis is not as high as it could be.Nope.
Here are two of many articles that do not include beta in the voltage gain formula:
No, AudioGuru is right that voltage gain is independent of Beta. But the real simulation to try is with the source impedance in both cases, the only difference being the Beta. My contention is that with a source impedance, Beta will affect the output voltage.
The different currents caused different voltage gains.
If the operating current is not changed then the voltage gain is not affected by different beta.
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