Systematic Design Methodology for CMOS Millimeter-Wave Power Amplifiers With an $E$ -Band Fully Differential Implementation in 16-nm FinFET

The selection of the appropriate technology is a key problem for millimeter-wave (mmW) circuits, especially for power amplifiers (PAs), due to the stringent power and efficiency requirements, reliability limitations, and cost considerations. This is particularly problematic in the case of complementary metal-oxide-semiconductor (CMOS) processes, which operate close to their limit in this kind of application. Technology choices are typically made based on the radio frequency (RF) figures of merit (FoMs) of the transistors or the quality factor of the inductors, which provide only limited insights into the performance of the target circuit. This article proposes a systematic design methodology based on two circuit-specific metrics, namely the PA FoM from the International Technology Roadmap for Semiconductors (ITRS) for the amplifying stages and the transducer power gain for the matching networks (MNWs). The methodology is demonstrated for a simple circuit architecture based on neutralized differential pairs (NDPs) and transformer-based MNWs. As a proof of concept, a three-stage fully differential $E$ -band PA prototype in a 16-nm FinFET process is designed, fabricated, and characterized. The prototype achieves a saturated output power of 15.2 dBm, small-signal gain of 34.9 dB, and power-added efficiency (PAE) of 30.3% at 70 GHz, which is a competitive performance with previous art in the $E$ -band in FinFET technologies.