40-GHz CMOS subharmonic Gilbert mixer with quadrature injection-locked frequency divider

Recently, an advanced complementary-metal-oxide-semiconductor (CMOS) technology is favorable for circuit design at high frequencies, and it is also demonstrated in the microwave and millimeter-wave regimes. Mixers are one of key parts in a transceiver. A double balanced Gilbert cell mixer has advantages in terms of a conversion gain, isolation, and compact size. A subharmonic mixer is still a popular choice because a local oscillator (LO) frequency is only half of an RF frequency. It overcomes conventional difficulties in generating high-frequency LO signals for a fundamental mixer. Further, a quadrature LO input is needed for the subharmonic Gilbert mixer. The quadrature generator can be implemented by RC-CR polyphase filters or divide-by-2 frequency dividers. Although a polyphase filter is a passive component without dc power consumption, power loss and phase noise are introduced. Furthermore, in a CMOS process, RC-CR polyphase filters have larger parasitic effects and larger process variations at high frequencies. The polyphase filters based on CMOS technology are not suitable for a quadrature generator at high frequencies. Otherwise, the most precise quadrature signal generation is offered by using divide-by-2 frequency dividers. The little LO pumping power and the broadband quadrature-output signal are benefits in the differential-input divide-by-2 frequency dividers. In this paper, using the standard 0.13-mum CMOS technology, we propose the 40-GHz leveled-LO subharmonic Gilbert down-converter with the quadrature LO input generated by two injection-locked frequency dividers (ILFDs).