C-D is the variable resistance area, the corresponding Vgs voltage corresponds to a certain Vds voltage Vgs voltage reaches the maximum value, and Vds voltage reaches the minimum value. Since the Id current is ID constant, the Vds voltage is the difference between ID and the on-resistance of the MOSFET. product
Based on the drain conduction characteristic curve of the MOSFET, it can be intuitively understood that when the MOSFET is turned on, the Miller plateau in the process of crossing the turn-off region, the constant current region and the variable resistance region is the constant current region. The MOSFET works in the amplified state, and the Id current is Vgs voltage and transconductance product.