A Current-Shared Cascade Structure With an Auxiliary Power Regulator for Switching Mode RF Power Amplifiers

In this study, we propose an auxiliary power regulator (APR) for the current-shared cascade (CSC) structure of the driver stages of RF CMOS power. Although the CSC structure provides a method to reduce the power consumption at the driver stages of a differential power amplifier (PA), it is difficult to obtain optimum levels of effective supply voltage for the first and second driver stages. Additionally, the transistor sizes of the first and second driver stages of the CSC structure must be identical to ensure the proper operation of the PA. Thus, in this work, we propose an APR structure that ensures the proper operation of a PA with different transistor sizes in its first and second driver stages. To prove the feasibility of the proposed technique, we designed the PA with a CSC structure using an APR. From the measured results, we successfully verify the feasibility of the proposed structure. Additionally, we provide experimental results for a typical CMOS PA to determine the optimum supply voltage for the second driver stage.