In accordance with an embodiment, a method for operating a millimeter-wave power amplifier including an input transistor having an output node coupled to a load path of a cascode transistor includes: receiving a millimeter-wave transmit signal at a control node of the input transistor; amplifying the millimeter-wave transmit signal to form an output signal; providing the output signal to a load coupled to an output node of the cascode transistor; and adjusting a first DC bias current of the input transistor to form a substantially constant second DC bias current of the cascode transistor.

Embodiments of a passive buffer circuit and a wideband communication circuit that uses the passive buffer circuit are disclosed. In an embodiment, the passive buffer circuit includes buffer elements connected between input terminals and output terminals that are connected to input terminals of a communication component circuit with a plurality of input transistors. Each of the buffer elements provides a first path with a resistor and a second path with a series-connected capacitor and inductor. The passive buffer circuit further includes current sources connected between the output terminals and at least one fixed voltage and a feedback loop from the input transistors to the current sources to control direct current (DC) voltage at each of the input terminals of the communication component circuit. The feedback loop includes an error amplifier that controls the current sources based on voltages on the input transistors with respect to a reference voltage.