Design, Implementation and Characterization of a High-Power Class D Audio Amplifier Evaluation Board Based on the IRS2461S Driver

This thesis discusses the design, implementation and experimental validation of the RCF IRS2461S Evaluation Board, a high-voltage, self-oscillating Class D audio amplifier prototype based on the Infineon IRS2461S gate driver. Class D switching amplifiers are widely used in modern high-power audio applications because of their high efficiency and power density. In professional sound-reinforcement systems, where subwoofers and line arrays require very high output power, increasing the supply-rail voltage is an effective way to obtain higher output power on larger load impedances, while also increasing the available voltage headroom. However, this approach introduces several design challenges, including high-voltage switching, MOSFET selection, protection design, thermal management, power-supply generation and PCB layout. The project was developed with reference to the RCF DIGIPRO 5, a two-channel Class D power amplifier module currently used as a benchmark in several RCF systems. The proposed evaluation board shares several architectural concepts with this reference module, but exploits the higher offset-voltage capability of the IRS2461S driver, which allows the implementation of a Class D power stage operating with a total bus voltage up to 400 V. In this work, a single-channel half-bridge prototype supplied by nominal +/- 140 V rails was designed, with the aim of moving the 2 kW output-power class toward a single 4Ω channel. The thesis presents the theoretical background of Class D audio amplification and self-oscillating architectures, followed by the complete design of the evaluation board, including the preamplifier, IRS2461S driver section, integrator, bootstrap network, protection circuitry, power half-bridge, LC output filter, dual pre- and post-filter feedback network, power-supply section and PCB layout. The practical implementation, debugging process and experimental tests are then discussed, with particular attention to the main critical issues encountered during prototyping. Through a detailed analysis of the results of the power and characterization tests on 16 Ω, 8 Ω and 4 Ω, the IRS2461S Evaluation Board was proven as a successful high-voltage Class D platform intended to extend the power capability of RCF amplifier modules. The prototype correctly reached self-oscillation and showed clean switching transitions at the nominal high-voltage rails. The power tests confirmed the effectiveness in terms of output power and efficiency: the amplifier reached 1018 W on 8 Ω and 1894 W on 4 Ω with THD+N=1%, delivered burst powers up to 1870 W on 4 Ω with +/- 140 V rails and 2248 W with +/- 150 V rails, and achieved efficiency values up to approximately 91%. Compared to the DIGIPRO 5, the prototype is not yet competitive in terms of distortion, noise, protection integration and overall product maturity. Nevertheless, it successfully demonstrates the feasibility of the proposed high-voltage self-oscillating Class D platform, showing that the increased voltage headroom enabled by the IRS2461S can extend the power capability of future RCF amplifier modules and provide the basis for a more refined high-power Class D design.