Shared Envelope Tracking for Time-Delayed Power Amplifiers in Phased Array Systems

Analysis shows that multiple time-delayed power amplifiers can share a single envelope tracker and provide a significant improvement over statically supplied amplifiers. Phased arrays are a suitable application of this technique. Our analysis shows a 15 point efficiency improvement over a static supply when amplifying a two-tone signal. We claim that sharing an envelope tracker is justified when 1/2 ≫ Δf/f0 sin(θ) (N-1), where Δf/f0 is the fractional bandwidth of the signal, θ is the maximum steering angle, and N is the number of elements sharing an envelope tracker. Closed form analytic solutions of a two-tone signal are presented to verify the concept.