why id is constant during Miller plateau ?

[kenddo]

hi all ,
i saw this curve in many books ，I knew in mosfet id=gm(vgs-vth),but when vds is falling ， IL=(VIN-VDS)*t/L，IL=ID which should be rising !

so id should be constant or rising? the picture shows me it is constant ,why?:?:

 

[kripacharya]

There are many texts which actually explain this.
Here is a quick one which has a lot of info :

**broken link removed**

 

[dick_freebird]

Miller feedback enforces constant dV/dt through the
MOSFET gain (gm) near threshold, against the gate drive
current limit and/or total Rg and available Vgs. Constant
dV/dt means constant C*dV/dt=I. Once the drain bottoms
out then feedback stops and Vgs rises.