60 GHz Reflection Type Phase Shifter based on liquid crystal

For the first time, a compact 60 GHz band phase shifter incorporating liquid crystal (LC) is presented. Based on the Reflection Type Phase Shifter (RTPS) structure, it comprises a 3-dB coupler and tunable reflective loads formed on a nematic LC substrate. The LC used to form the substrate is known as E7. Biasing of the LC is achieved using an external electric field, allowing for the control of the reactance of the reflective loads. To facilitate on-wafer measurements and the application of the electric field to the LC, a transition from the microstrip line to the CPW is used. Preliminary measurement results for this RTPS show a differential phase shift of over 130 degrees, a figure of merit of 11.4°/dB and return losses better than -10dB at 61 GHz. © 2010 IEEE.