I am facing the problem that the miller effect of the large power transistor will diode connect the transistor, which in the end makes the transistor a resistor. Really want to know if there is any other good design technique to reduce the miller effect in addition to cascode structure ?
if your circuit is a differential one, you could try the so called "neutralization" technique. If not, other than minimizing the gate to drain cap or using a low impedance in the drain node, I have no ideas myself.