Heavily doped buried layer to reduce mosfet off capacitance

A method of operating a circuit comprising a metal-oxide semiconductor field effect transistor (MOSFET) to reduce off capacitance of the MOSFET, the method comprising:

• obtaining a MOSFET comprising:
• a source region and a drain region of a first conductivity type;
• a body region of a second conductivity type, the body region underlying at least a portion of the source region and the drain region;
• and
• a buried region of the first conductivity type, the buried region disposed between the body region and a substrate, the buried region configured to reduce a capacitance between the source region and the drain region in response to an indicated voltage applied between the body region and the buried region;
• fixedly coupling a first voltage to the buried region;
• and
• reducing the off capacitance of the MOSFET by coupling a second voltage to the body region to reverse bias a junction between the body region and the buried region when the MOSFET is turned off.

A circuit to selectively adjust an off capacitance of a metal-oxide semiconductor field effect transistor (MOSFET), the circuit comprising:

• a MOSFET formed on a substrate, the MOSFET comprising:
• a source region and a drain region of a first conductivity type,
• a body region of a second conductivity type disposed adjacent to the source region and the drain region, and a buried region of the first conductivity type, the buried region underlying at least a part of the body region;
• and
• a sub-circuit configured to:
• provide a reverse biasing voltage between the body region and the buried region when the MOSFET is turned off, and
• provide the body region and the buried region with a same voltage when the MOSFET is turned on.