The Kink phenomenon and its effect on broad band matching are introduced and analyzed,and a novel composite HBT basing on the principle of negative feedback is proposed.According to the small signal analysis and the computer software simulation,the output impedance of a composite transistor could be represented by a "shifted" series RC circuit,and keep a constant value.A test die chip using 2 μm InGaP/GaAs HBT technology was fabricated.The measurement shows that the new composite HBT structure is able to eliminate the Kink phenomenon over a very broad band from 0.1 GHz to 20 GHz(nearly reaches this HBT's cutoff frequency).Furthermore,the measurement is quite close to the results from theoretical analysis and the computers simulation.In a word,the composite transistor structure can simplify the design of a broadband amplifier.Besides,the increase of chip area and power consumption is negligible.