A method to design planar and low insertion loss phase shifter with broadband characteristic of 90o difference is presented by utilizing the nonlinear phase characteristic of the simplified composite right-/left-handed transmission line. The measured results show that the proposed phase shifter achieves 2.9~8.4 GHz (97.3%) bandwidth with return loss ≤-10 dB, insertion loss ≤0.7 dB and phase instability ≤±5°. Whereas, the relative bandwidth of the conventional difference phase shifter is only 11% when it simultaneously satisfying the above indexes. The proposed structure is simple in design and is easy to be fabricated.