Broadband digital phase shifter based on composite right/left-handed transmission line

The broadband digital phase shifters are valuable for the modern phase array antennas. Under balanced condition, composite right/left-handed transmission line (CRLH TL) is broadband because of its unique hyperbolic-linear dispersion relations. A broadband 4-bit digital phase shifter based on the broadband proper v of CRLH TL is designed. When the absolute error is less than +/-5 degrees, for the 180 degrees stage of the phase shifter. the relative bandwidth achieves 31.3%, while the conventional 180 degrees switched line phase shifter only achieves 8.9%. And the unique hyperbolic-linear dispersion relations are also able to minimize the area of the phase shifter. A simple circuit to test the right-handed (RH) effect of the left-handed (LH) TL is fabricated and used successfully, in the design process of the 4-bit digital phase shifter. The simulation and experiment results show that the design method of the phase shifter is feasible. (C) 2008 Wiley Periodicals, Inc.