Can we interchange source and drain in a MOSFET?
Theoretically, the drain and source can be swapped, and when you do this, the source becomes the drain and the drain becomes the source. For an N-MOSFET, the source is the lower potential, and the drain is the higher potential.
What does the drain do in a Mosfet?
One injects carriers into it (source) the carriers are removed by the other terminal (drain). Many FETs make no distinction between source and drain. So which terminal is the source and which is the drain depends on the polarity of the Voltage connected to it. For N channel, the drain is the more positive terminal.
When do MOSFETs have voltage drop across source and drain?
If you don’t give it enough gate voltage (many MOSFETs are specified at 10V, some at 4.5, and fewer at 1.8 or 2.5) you may get a much higher Rds (on). BJT: Voltage drop from collector to emitter is dependent on current but not linearly. At low current and with high base current, the BJT might have a voltage drop of tens of millivolts.
When is the MOSFET in the on state?
When the FET’s gate-to-source voltage (V GS) exceeds the threshold voltage (V TH ), it is in the “on state,” and the drain and source are connected by a channel with resistance equal to R DS (on). However, if you are familiar with the actual electrical behavior of a MOSFET, you should readily recognize…
How is drain current related to gate voltage?
If you put 3V on the gate to source then the drain current will be zero until you apply a drain-source voltage (usually via current limiting device such as a resistor). It doesn’t convert input voltage to output current like a solar panel converts light to voltage.
What’s the difference between a BJT and a MOSFET?
At more than the base voltage it’s no longer considered to be saturated. One interesting difference between the two is that the MOSFET drops almost exactly zero voltage at zero current, whereas the BJT drops perhaps 10 mV at zero collector current (assuming you put some reasonable current in the base- that’s not reflected in the above curve).