An Ultra-Compact Bidirectional <inline-formula> <tex-math notation="LaTeX">$Ka$</tex-math> </inline-formula>-Band Front-End Module With 3.8-dB NF and 13.5-dBm OP<inline-formula> <tex-math notation="LaTeX">$_{1\,\text{dB}}$</tex-math> </inline-formula>

This letter presents an ultra-compact bi-directional <inline-formula> <tex-math notation="LaTeX">$Ka$</tex-math> </inline-formula>-band front-end module (FEM) in 65-nm CMOS technology. In this design, the receiver (RX) path is stacked into the transmitter (TX) path by using a magnetic self-canceling technique, improving area efficiency greatly with negligible performance penalty. Furthermore, a three-inductor coupled resonator is elaborately designed to realize the functions of the balun and input&#x2013;output matching network (MN) of the RX/TX simultaneously. The measurement results demonstrate that the proposed FEM achieves 18.2-dB peak gain with a 3.8-dB minimum noise figure (NF) in RX mode, and 26-dB peak gain with 13.5-dBm 1-dB compression output power (OP<inline-formula> <tex-math notation="LaTeX">$_{1\,\text{dB}}$</tex-math> </inline-formula>) in TX mode. The core size of this proposed design is only 0.06 mm<inline-formula> <tex-math notation="LaTeX">$^2$</tex-math> </inline-formula> which is only 20<inline-formula> <tex-math notation="LaTeX">$\%$</tex-math> </inline-formula>&#x2013;50<inline-formula> <tex-math notation="LaTeX">$\%$</tex-math> </inline-formula> of the size occupied in prior works.