Current-mode active termination

Embodiments of the present invention, as further described below, provide active termination circuits that can be used with power transmitter circuits. Embodiments reduce power loss due to impedance matching and increase power efficiency in power transmitter circuits. In particular, embodiments provide active termination circuits that can be configured to draw minimal amounts of the output current generated by the power transmitter circuits. At the same time, embodiments achieve optimal impedance matching, thus enabling optimal power transfer to the load. Further, embodiments can be controlled adaptively in real time to reduce parasitic effects on power transfer and to optimize impedance matching. Embodiments can be implemented using various transistor technologies (e.g., MOSFET, BJT, etc.), and can be used with a variety of power transmitter circuits, including, for example, power DACs, analog/digital RF transmitters, and analog/digital PAs.