Cascode amplifier

FvM said:

1. I don't recognize a cascode amplifier.
2. Infinite voltage causes gate oxide and embedding air breakdown. Ask meaningful questions is you want useful answers.

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BradtheRad said:

High side P type conducts less as you raise its bias voltage. (It shuts off when bias approaches supply voltage.)

High side N type conducts more as you raise its bias voltage.

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BradtheRad said:

With a bjt there are two internal diodes which the bias can go through. Normally it only goes through the emitter diode.

However your experiment applies bias voltage which overcomes the supply voltage at the collector. Current travels up in reverse direction to the power supply. It's an abnormal method of using a bjt therefore the output is abnormal.

As for mosfets... They do not act exactly the same way as a bjt. They might have different threshold bias voltages which must be reached before they start to turn on. They have a body diode which we must take into account.

If the mosfet is healthy mosfet then it responds to bias voltage but its insulated gate does not pass current. However if the gate has been perforated then the device acts abnormally. Mosfets are sensitive to being ruined by static charge, and even 40 or 50 volts could be sufficient to alter its operating characteristics permanently.

You didn't make it clear whether your circuit is hardware or simulated. It might help if you run tests on your transistors individually, in the most basic circuits which demonstrate how it performs over a normal range of bias and supply voltages.

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