slow start circuits for switching mode power supply

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Hi,All, circuits is here. I want to let the high side voltage slowly
grow on both ends of load resistor "R". which is better? I tried the
circuits on the right corner but there was 2.5 Volt acrossing drain
and source, why? when I increase the load current, the mosfet got hot,
was it fully on with very little power consumption? The lower left
circuits worked but I still saw a +5V pulse across my load resistor.
It looks the upper left is best suit for my circuits?

http://farm4.static.flickr.com/3112/2620434318_70a5a08dd5.jpg?v=0

Thanks for watching.