Design of a Load Modulated Balanced Amplifier with a Two-Stage Control Power Amplifier

While an ideal Doherty power amplifier has a linear response, the load modulated balanced (LMBA) compressive response under conditions. This inherent nonlinear characteristic is due to lower contribution of single auxiliary device as transistors approach compression. article presents LMBA with two-stage control signal in place device. The idea preserve high and constant gain across high- low-power regions by tuning match gain. An optimal trajectory can be found for high-efficiency design appropriately terminating second harmonic while ensuring impedance all devices. At same time, setting output from device, sufficient provided linearize main beyond back-off boundary. As proof concept, prototype designed implemented. experimental measurements demonstrate drain efficiency 59%–64% at maximum 46%–52% 7.5 dB over target frequency range 3.3–3.8 GHz.