Abstract: The present invention discloses a bandpass amplifier having gain and bandpass performance. The bandpass amplifier includes an input match unit for matching the gain of the amplifier and having a first filter response; a first bias unit electrically connected to the input match unit for driving the first terminal of the amplifier and having a first high pass filter response; a gain stage electrically connected to the first bias unit for providing the flat gain of the amplifier; a second bias unit electrically connected to the gain stage for driving the second terminal of the amplifier and having a second high pass filter response; and an output match unit electrically connected to the second bias unit for matching the gain of the amplifier and having a second filter response.

Abstract: A dual-band bandpass filter with stepped-impedance resonators uses only one circuit to generate dual-band effect. It adopts the principle of stepped-impedance resonator, which contains a connecting section and two coupling sections. The impedance and electrical length of the connecting section and coupling sections conforms to a selected condition to generate two passbands at desired frequencies. A multi-layer broadside-coupled parallel lines structure may be applied to increase coupling-amount between the parallel lines so that the dual-band bandpass filters have broader bandwidth and less loss.