Design, Control and Performance of Tracking Power Supply for a Linear Power Amplifier

Power amplifiers are widely used in consumer and industrial applications and are based on either a linear power amplifier or switch-mode power amplifier design. By combining the linear power amplifier with a switch-mode tracking power supply, a hybrid power amplifier is formed that maintains a high quality output while having a high efficiency. This paper presents a hybrid amplifier that is constructed with a novel boost-type tracking power supply and provides an excellent performance. A design method for the output filter using the power supply ratio rejection (PSRR) of the linear power amplifier is proposed. This method ensures that the amplifier output voltage has minimal switching frequency components as well as being able to quickly track changes in the output voltage. A control system design method is presented that ensures good performance in the control of the constant inductor current of the switch-mode tracking stage and a high rejection of output voltage disturbances. A laboratory prototype experimentally verifies the theoretical analysis