Designing at Millimeter-Wave
This paper presents a triple coil variable transformer that can be used to design RF blocks for millimeterwave 5G transceivers. By employing a third coil with a varying capacitive load in a two coil transformer, simultaneous dual band or a wide-band response can be achieved ranging from 20 GHz to 50 GHz. The idea is validated using simulations and fabricated using 45 nm CMOS SOI technology. In addition, reasons for mismatch between the simulated and measured results are studied. Furthermore, a modified switching configuration is proposed to alleviate the problems with the original design.