Design of wideband 90° phase shifter using compact CRLH structure

To satisfy several standards of wireless systems, the wideband phase shifters become essential. In this paper, we present the design and testing of a compact wideband 90° phase shifter with small phase error using CRLH transmission line. The wideband phase shifter is obtained by subtracting of two phase shift parts. The properties of the CRLH transmission line are analyzed and the empirical formula is given to determine the phase shift of the transmission line against with the length of the interdigital capacitance. According to the formula, a 90° phase shifter with a phase error of ±3° has been achieved. The implemented phase shifter works from 4.225GHz to 5.709GHz with a small size of less than 35mm×50mm in total. The measured results show good agreement with the simulated results.