Design of a Wideband Differential Phase Shifter with the Application of Genetic Algorithm

In this paper, a wideband differential phase shifter has been analyzed and designed using Genetic Algorithm (GA). The differential phase shifter consists of two fixed main lines of length lambda/2, and parallel open and short stubs of length lambda/8, which are shunted at the edge points of the main lines, respectively. With the application of GA, an impedance match and minimum phase deviation for the desired phase shift over a wide frequency band are obtained. In order to verify the optimum results, simulation experiments are made and a 45 phase shifter is fabricated and measured. The phase shifter exhibits an impedance bandwidth (vertical bar S-11 vertical bar < -10 dB) and a consistent 45 degrees (+/- 2 degrees) phase difference bandwidth around 66%.