Adaptive LDMOS Power Amplifier with Constant Efficiency

Achieving constant high efficiency is important in adaptive power amplifier design. This paper highlights the achievement of constant efficiency across wide power levels for power amplifiers with tuned drain supply while having a fixed load impedance network. Due to the non-linear behavior of the trans-conductance at lower drain voltage, class AB bias scheme is implemented. Constant efficiency of 43% across a wide range of power levels (1.2 to 5.3 Watt) is demonstrated experimentally.