DUAL-FREQUENCY MATCHING TECHNIQUE AND ITS APPLICATION TO AN OCTAVE-BAND (30-60 GHZ) MMIC AMPLIFIER

A single-stage dual-frequency matching network that can simultaneously transform a transistor reflection coefficient to zero at two separate frequencies (a lower frequency f(L) and a higher frequency f(H)) is p roposed. The network is made by adding a shorted stub, the length of w hich is a quarter-wavelength at f(H), to a conventional L-section matc hing network composed of a series transmission line and an open stub. The concept of dual-frequency matching is based on the fact that the s ynthesized shunt admittance of the open and shorted stubs changes from capacitive at f(H) to inductive at f(L). By means of the single-stage matching network, broad-band amplifier performance, the bandwidth of which is given as similar to (f(H)-f(L)), can be easily obtained with almost the same design procedures and circuit area used for convention al narrow-band amplifiers. In this paper, the function of the dual-fre quency matching network is analyzed in detail and an application of th e matching technique to a two-stage amplifier is described. A broad-ba nd performance of \S-21\>7.4 dB at 27.0-62.5 GHz has been achieved wit h a GaAs P-HEMT two-stage MMIC amplifier.