Planar Chain Power Combining Amplifier

The distance between signal paths is limited in the power combining amplifiers using parallel multi-port microstrip lines as the output ports. There is no enough room for the unit amplifiers and their biasing elements. With the problem, a planar chain power divider/combiner is presented in this paper. A four-path planar divider/combiner is designed and fabricated. Its measured results are given: the return loss is less than -13 dB on the wide bandwidth of 2.0～4.5 GHz. The insertion loss is less than 0.8 dB. Additionally, a four-element power combining amplifier is also designed and fabricated. Its small signal gain on the bandwidth of 2.0～4.5 GHz is 13～19 dB, the saturated output power at 3.2 GHz is 26.4 dBm, and the power-combining efficiency is up to 85%.