GaInP/GaAs HBT sub-harmonic Gilbert mixers using stacked-LO and leveled-LO topologies

Abstract—This paper discusses and demonstrates the most popular sub-harmonic Gilbert mixers in 2- m GaInP/GaAs HBT technology. High two local oscillators (2LO)-to-RF isolation is important to alleviate the self-mixing problem of the sub-har-monic mixer. The demonstrated GaInP/GaAs HBT stacked-local oscillator (LO) mixer topology has achieved the best 2LO-to-RF isolation when compared with the previous literature. On the other hand, the leveled-LO sub-harmonic mixers have advantages in terms of the high speed and low dc supply voltage at the cost of much larger LO pumping power. Among all the structures, the bottom-LO sub-harmonic mixer has the lowest current con-sumption and the simplest circuit structure at the expense of the 2LO-to-RF isolation. Index Terms—DC offset, GaInP/GaAs HBT, Gilbert mixer, self-mixing, sub-harmonic mixer, two local oscillators (2LO)-to-RF iso-lation. I