Analysis of a Three-Way Voltage-Mode Digital Doherty Power Amplifier for Bluetooth Applications

This paper investigates a multi-class, Three-Way digital Doherty power amplifier (DDPA) for Bluetooth applications, that achieves a peak output power of 20 dBm, using a 0.7 V supply voltage. The proposed Three-Way DDPA is made of three Switched-Capacitor Power Amplifiers (SCPAs), power combined with an on-chip Series Combining Transformer (SCT). The Three-Way DDPA is implemented in a 22 nm bulk CMOS technology, with the main goal of supporting all the BT/BLE power classes, efficiently. The technique of the Dual Line Up (DLU) is leveraged to achieve good efficiencies both at low and high power. Simulation results show that the proposed power amplifier features three efficiency peaks at $\mathbf{0}, \mathbf{1 0}$ and $\mathbf{1 9. 3 ~ d B}$ Power-Back Off (PBO) with drain efficiencies of $\mathbf{4 7 \%, 4 7 \%}$, and $\mathbf{4 0 \%}$, respectively.