What is the drain-source on-resistance of a MOSFET?

How to measure drain-source on-resistance of a MOSFET

You can trace the drain-source on-resistance of a MOSFET as a function of an applied Vgs by using two Keithley 2400 SourceMeter SMUs . You can also perform an R_DS(on) resistance measurement using a simple oscilloscope. Watch the video for step-by-step instructions on how to measure R_DS(on) of a SiC MOSFET using source measure units and a control software. Also, review our application note on measuring power supply switching loss with an oscilloscope for more information on measuring dynamic on-resistance of MOSFETs.

问题：

What is the drain-source on-resistance of a MOSFET?

答案：

MOSFET switching devices operate in the on and off states. In the “on” state, the impedance of the switch is theoretically zero and no power is dissipated in the switch no matter how much current is flowing through it. In the “off” state, the impedance of the switch is theoretically infinite, therefore no current is flowing and no power is dissipated.

The drain-source on-resistance (R_DS(on)) is the effective resistance between the drain and the source of a MOSFET when it’s in the on state. This occurs when a specific gate-to-source voltage (V_GS) is applied. In general, as the V_GS increases, the on-resistance decreases. The lower the MOSFET on-resistance, the better because a low resistance reduces undesired power dissipation, improving the power efficiency of the device.

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