Doubly-Tuned Transformer-Based Class-E Power Amplifiers in 130 nm BiCMOS for mmWave Radar Sensors

This paper presents high-efficiency V-band and E-band power amplifiers (PAs) for mmWave radar sensors. High-efficiency mmWave operation is enabled by a doubly-tuned transformer-based Class-E output network which allows increasing PA device size beyond the limit imposed by traditional Class-E principles, while preserving the Class-E voltage and current waveforms. Two primary prototypes (a 79-GHz centered two-stage PA and a 63-GHz centered single-stage PA) along with a 79 GHz single-stage test chip have been designed and fabricated in a production 130 nm BiCMOS process. The two-stage PA also employs a Class-E driver stage with a split-and-combine 45-degree transformer to ease driving the large switching PA devices. The measurements results yield a peak PAE of 30.5/34.7% with an output power of 17/18.1 dBm for the 79 GHz two-stage and single-stage 63 GHz PAs, respectively (along with a peak PAE of 32.6% at 17 dBm for the 79 GHz single-stage test-chip). These are the best-in-class PAE numbers reported for V-Band and E-Band PAs in any silicon process, demonstrating the efficacy of the proposed doubly-tuned transformer-based Class-E network.