An ultra wideband (UWB) quasi-circulator implemented with distributed amplifiers using the 90 nm complementary metal-oxide-semiconductor (CMOS) technology is presented. The proposed quasi-circulator is composed of two distributed amplifiers and two Lange couplers to attain UWB performance at 14 to 67 GHz. Good insertion gain of 4.3 dB to -3.5 dB, low noise figure of 7.1 to 12.6 dB, and good isolation characteristic of |S31|better than 20 dB can be obtained. Using the distributed amplifier technique, the proposed quasi-circulator offers significant advantages of broad operation bandwidth, high isolation, low noise figure, and good insertion gain.
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