A 25–31-GHz Compact True Power Detector With >33-dB Dynamic Range and Intrinsic Phase Offset Compensation in 40-nm Bulk CMOS

This article presents a compact mixer-based true power detector integrated within a Ka-band power amplifier (PA). By performing capacitive voltage sensing and inductive current sensing at the primary coil, the compact power detector eliminates the need for additional area-consuming passive components while still allowing the PA to maintain a single-ended antenna output. The control of magnetic coupling with the secondary coil is achieved by exploiting magnetic flux cancellation rather than increasing the physical distance between coils. The active mixer multiplying the voltage and current uses current bleeding technique that simultaneously suppresses the flicker noise and enhances linearity, leading to a state-of-art dynamic range. Without phase shifters or resistor termination, the overall power detector achieves intrinsic phase compensation by matching the delays between the voltage and current sensing paths. Fabricated in a 40-nm CMOS process, the power detector occupies a core area of $3520~\mu $ m2 and covers a detectable power range from −18 to +15 dBm across 25–31 GHz with 12.1-mW power consumption.