Embodiments of RF amplifiers and RF amplifier devices include a transistor, a multiple-section bandpass filter circuit, and a harmonic termination circuit. The bandpass filter circuit includes a first connection node coupled to the amplifier input, a first inductive element coupled between the first connection node and a ground reference node, a first capacitance coupled between the first connection node and a second connection node, a second capacitance coupled between the second connection node and the ground reference node, and a second inductive element coupled between the second connection node and the transistor input. The harmonic termination circuit includes a third inductive element and a third capacitance connected in series between the transistor input and the ground reference node. The harmonic termination circuit resonates at a harmonic frequency of a fundamental frequency of operation of the RF amplifier.