Semiconductor on insulator (SOI) switching circuit

A wireless communications device comprising a power amplifier and an antenna, said wireless communications device further comprising:

• a switching circuit controlled by a switch control signal and interposed between said power amplifier and said antenna, said switching circuit including:
• a plurality of cascaded transistors fabricated in a device layer situated over a buried oxide layer and a bulk semiconductor layer, each of said plurality of cascaded transistors having a source/drain junction that does not contact said buried oxide layer, thereby forming a source/drain junction capacitance;
• at least one trench extending through said device layer and contacting a top surface of said buried oxide layer, thereby electrically isolating at least one of said plurality of cascaded transistors in said switching circuit so as to reduce voltage and current fluctuations in said device layer.

A wireless communications device comprising an antenna and a low noise amplifier, said wireless communications device further comprising:

• a switching circuit controlled by a switch control signal and interposed between said antenna and said low noise amplifier, said switching circuit including:
• a plurality of cascaded transistors fabricated in a device layer situated over a buried oxide layer and a bulk semiconductor layer, each of said plurality of cascaded transistors having a source/drain junction that does not contact said buried oxide layer, thereby forming a source/drain junction capacitance;
• at least one trench extending through said device layer and contacting a top surface of said buried oxide layer, thereby electrically isolating at least one of said plurality of cascaded transistors in said switching circuit so as to reduce voltage and current fluctuations in said device layer.