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Does MOSFET increase voltage?
The maximum input voltage and charging current can be raised with the addition of more P-MOSFETs in series. The downside is the voltage drop across each P-MOSFET of about 5V. Larger C1 capacitances than 100µF would linearize the charging curve at even higher voltages, or, of course, a DC input could be used.
Do MOSFETs amplify?
If we provide a small signal (time-varying) and apply the DC bias at gate or input, then under the right situation the MOSFET provides linear amplification.
What happens when the voltage of a FET goes low?
It won’t like that. Most FETs have a max G-S rating of 15-20 V. Your circuit also lacks a pulldown, so the output voltage is undefined when the 12 V line goes low. This circuit will invert, but since its output is going into a microcontroller that shouldn’t matter.
When to turn on a 12V transistor?
The transistor will turn on when the “12V” line gets to around 6 V. However, with the 91 kΩ resistor in series with the “12V” line, high voltages on that line won’t bother anything. A spike will just cause a little more base current, which won’t matter since the transistor is already saturated with 12 V on the line anyway.
What happens to the drain voltage of m2?
Therefore a big change of the Out voltage causes a very small change of the drain voltage of M2 (voltage is stabalized here). Therefore the current changes not much and the output resistance of the cascode is very high. To answer this question, I will try to build the above circuit which you have step by step and explain intuitively at each step.
Why is output resistance less at drain terminal?
The output resistance seen at the drain terminal of M2 is Rds of the transistor M2. So, applying the same analogy that we discussed in the widlar current source, the fluctuation at the output terminal is less at the drain terminal of M2 due to the transistor M1.