Synthesis method for distributed amplifiers

Abstract

New design method is presented for distributed amplifiers (DA). It is shown that by proper design of the applied transmission lines (TL) between the active devices the image impedance and the cut-off frequency COF of the input or output line of the DA can be independently tuned. As a consequence, the phase mismatch between the lines of the DA can be adjusted independently from the termination conditions and from the capacitances of the applied transistor and thus flat gain characteristic can be achieved. The method is well applicable for nearly unilateral devices like HBTs [1] and yields the highest gain-bandwidth product.