A power harvesting circuit includes a new transmitter topology that ensures that no junction of thin oxide transistors forming the power harvesting circuit will experience a voltage across junctions of the transistors that is more than a maximum tolerable junction voltage. A supplemental power feed circuit operates to provide a supplemental feed current to components in a transmitter circuit when power harvested from a receiver circuit is insufficient to adequately power these components of the transmitter circuit, which may occur during high frequency operation of communications channels coupling the transmitter and receiver circuits. The supplemental power feed circuit also operates to sink a shunt current when power harvested from the receiver circuit is more than is needed to power the components in the transmitter circuit.