A Method to Shorten the Size of Amplifiers Using Vertically Periodic Defected Ground Structure

This paper presents a method to reduce the size of amplifiers using a vertically periodic defected ground structure (VPDGS). The microstrip line combined by VPDGS provides 3 times higher slow-wave factor than standard microstrip line. Due to the increased slow-wave effect, the electrical length of the microstrip line with VPDGS is longer than that of the standard microstrip line for the same physical length. Using this property, the physical lengths of microstrip lines in the matching networks of an amplifier are reduced by inserting VPDGS in order to preserve the same electrical length, matching, and, ultimately, performances. The resultant lengths of the microstrip lines with VPDGS in input and output matching networks are only 38.5% and 44.4% of the original microstrip lines, respectively. It is shown that the measured performances of the reduced amplifier are maintained even after the lengths of microstrip lines in matching networks have been shortened by VPDGS.