C.-H. ChangJ.-F. KiangJEAN-FU KIANG2018-09-102018-09-102009-06http://scholars.lib.ntu.edu.tw/handle/123456789/352409Fig. 4 show the performance of circulator. Both the insertion losses S 21 and S 32 are ?3 dB at 24 GHz. The isolation all are lower than ?20 dB at 24GHz. The return losses S 11 and S 33 are lower than ?10 dB at 24 GHz. The active balun in cascade with the in-phase combiner as shown in Fig.2 successfully isolate the signal from port 1 to port3. The buffers effectively decrease the insertion loss and increase the isolation. Fig. 5 show the performance of VCO, which has about 4 GHz wide of tuning range, and the phase noise is lower than ?100 dBc/Hz at 1 MHz offset over all the operation frequency band. Since the cross-coupled complementary circuit has lower parasitic capacitance and the varactor size is large, the tuning range can be significantly increased and only 2.9 mW is consumed by the VCO.[SDGs]SDG7conference paper10.1109/aps.2009.51718502-s2.0-71049183010