Dual-Mode RF Mixer for Low-Power Direct-Conversion Receiver

In this work, a dual-mode (DM) radio frequency (RF) mixer is studied and validated over the$K$-band to meet the ultralow-power requirement of direct-conversion receiver architectures. The proposed RF mixer combines two operation modes, namely, RF energy harvesting mode and RF mixing mode, which are implemented within a single passive multiport interferometric circuit. This approach aims at harvesting part of the RF energy for powering specific low-power active devices toward the energy autonomy of RF receiver systems. For this proof-of-concept study, a circuit is prototyped and tested. The experimental results show promising performance. Inter-port isolation better than 20 dB is achieved over a frequency range of 22–26 GHz, together with good RF-to-dc conversion efficiency (up to 45% with RF input power of 40 mW), and appreciable RF mixer conversion loss over a wideband (average 12.8 dB).