gaas substrate improves switch isolation gaas whilst offering improved performance compared with si cmos disadvantageously has higher manufacturing costs as such it would be beneficial to enhance the performance of si cmos rf microwave switches referring to fig1 b illustrated is a prior art microwave switch circuit 150 according to bergener et al that attempts to redress the performance issues of si cmos the microwave switch circuit 150 comprises four clusters or u201c groupings u201d of mosfet transistors identified in fig1 b as transistor groupings 133 134 137 and 138 two transistor groupings comprise u201c pass u201d or u201c switching u201d transistor groupings 133 and 134 and two transistor groupings comprise shunting transistor groupings 137 and 138 each transistor grouping comprises three mosfet transistors arranged in a serial configuration for example in the embodiment shown in fig1 b the switching grouping 133 includes three switching transistors m 133 a m 133 b and m 133 c similarly the switching grouping 134 includes three switching transistors m 134 a m 134 b and m 134 c the shunting grouping 137 includes three transistors m 137 a m 137 b and m 137 c similarly the shunting grouping 138 includes three transistors m 138 a m 138 b and m 138 c as shown in fig1 b microwave switch circuit 150 is controlled by two control signals sw and its inverse sw u2212 these control signals.