Basic Components in mm-Wave Design

Abstract

AbstractThe continued scaling of CMOS technology has made active devices fast enough to operate beyond 100 GHz. This scaling, optimized for digital design, is not just a free lunch but comes with extra challenges for the analog designer. Smaller devices lead to lower breakdown voltages and thus reduced voltage handling. This reduces power handling, linearity, and achievable signal-to-noise ratio. Furthermore, with the advent of FinFET, RF performance seems to flatten. The back end of line (BEOL) also changes with decreasing technology nodes. The amount of metal layers increases at the cost of thinner higher resistive connections, closer to the substrate. Although a thick top metal layer is provided for RF circuits despite the technology node, the connection between transistors and down to the transistors deteriorates. The design of passive components for mm-wave circuits differs greatly from analog and RF design, as well as the use case of these components. In this chapter, the active components, their key performance indicators, and how to use FinFET for mm-wave are the focus of Sect. 2.1. The passive devices are discussed in Sect. 2.2. Finally, in Sect. 2.3, the active and passive components are combined to form the basic widely adopted mm-wave amplifier used above 100 GHz and how to perform basic interstage transformer matching.KeywordsTechnology scalingFinFETTransformerInductanceCapacitanceImpedance matchingCMOSCoupled resonatorsCapacitive neutralizationWidebandBandwidthWideband matchingLayout techniquesTechnology comparison40 nm CMOS28 nm CMOSQuality factor