Injection lock power amplifier with back-gate bias

A structure, comprising:

• a transformer having a primary side and a secondary side, wherein output from the primary side is coupled to the secondary side, and a first power supply is connected to a center-tap of the primary side of the transformer;
• a pair of switching transistors, each transistor of the pair of switching transistors including a source node, a front-gate node, a back-gate node, and a drain node, wherein the pair of switching transistors are cross-coupled such that the drain node of each one of the switching transistors is connected to the front-gate node of the other switching transistor, and wherein the drain nodes of each of the switching transistors are connected to the primary side of the transformer;
• and
• a pair of injection transistors, each transistor of the pair of injection transistors including a source node, a front-gate node, a back-gate node, and a drain node, wherein the drain node of each one of the injection transistors is connected to the drain node of one of the switching transistors and the source node of each of the injection transistors is connected to the source node of each of the switching transistors,
• wherein an injection signal source is connected to the front-gate node of each transistor of the pair of injection transistors, and a bias voltage source is connected to the back-gate node of each transistor of the pair of switching transistors.

A method, comprising:

• cross coupling a pair of switching transistors, such that a drain node of each one of the switching transistors is connected to a front-gate node of the other switching transistor;
• connecting the drain nodes of each one of the switching transistors to the primary side of a transformer having a primary side and a secondary side;
• providing an injection current to the pair of switching transistors to oscillate the transformer;
• measuring output power from the secondary side of the transformer;
• determining if output power from both the primary side and the secondary side of the transformer are approximately equal;
• and
• responsive to the output power from both the primary side and the secondary side of the transformer not being approximately equal, controlling output power of the switching transistors by adjusting voltage to a back-gate of the switching transistors.