Envelope Tracking Linearizability of Power Amplifier

Envelope tracking (ET) linearizability of a power amplifier (PA) is studied in this paper. ET linearization can be explained as the cancellation between two intermodulation distortion (IMD) components [1,2]. The phase difference θ
₀
between the two IMD components is identified as the criterion of ET linearizability. The IMD improvement by incorporating ET module with PA can be analytically calculated in terms of θ
₀
. Excellent agreement between the prediction and measurement is achieved. Determination of θ
₀
using three-tone measurement is proposed and demonstrated. ET linearizability is an inherent feature of a standalone PA itself, and can be quantitatively predicted before incorporating an ET module.