This letter presents an ultra-compact bi-directional $Ka$ -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–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 $_{1\,{\mathrm {dB}}}$ ) in TX mode. The core size of this proposed design is only 0.06 mm2 which is only 20%–50% of the size occupied in prior works.

This paper presents an octave tuning-range LC VCO which can be used in the phase-locked loop to synthesis all frequencies up to the highest oscillation frequency. The proposed VCO employs the E-M mixed-coupling technique which compromises four LC tanks coupled either through magnetic or electric coupling, thereby generating four distinct resonances. Switched tail resistors are added to suppress FoM variation over the tuning range. To further enhance the phase noise performance, customized transistor designs are utilized instead of the PDK provided alternatives for a more compact layout to minimize wiring length from tank to active core. The proposed VCO, fabricated in 65nm CMOS process, demonstrates a 75.7% tuning range from 5 GHz to 11.1 GHz with an optimal -145.8 dBc/Hz phase noise at 10-MHz offset, corresponding to a figure-of-merit-tuning (FoM T ) of 205 dBc/Hz. Notably, the FoM T variation remains considerably small, at less than 2.5dB, over the entire tuning range.