In this paper an integrated stereo single-ended class D amplifier is presented. The amplifier is capable of delivering 2x100W in two 4? loads at a supply voltage of 60V. The amplifier has been realized in an SOI-based BCD technology. A second order feedback loop is used to suppress supply ripple and on-idealities in the output stage. In order to be suited for mass production practical issues such as robustness and EMC have been addressed.
Convention Paper 5502

10:00 h
B2 An Asynchronous Switching High-End Power Amplifier – Paul van der Hulst¹, André Veltman¹, René Groenenberg² - ¹Piak electronic design, Culemborg, Netherlands; ²Mueta, Wijk en Aalburg, Netherlands

Switching power amplifiers need an analogue low-pass filter between the power transistors and the speaker to prevent HF switching noise to enter the speaker. Cancellation of the non-linearities, as well as the (load dependent) frequency transfer of this filter is desired, but traditionally very difficult because of stability problems with filter-output feedback. A switching power amplification topology is presented which offers total control over the output filter dynamics and cancellation of the filter characteristics. The proposed amplifier uses a hysteresis circuit with a high-bandwidth capacitor-current feedback as PWM modulator. The output filter is thus an integral part of the modulator which dramatically improves control of the output. The result is a very high fidelity amplifier which is unconditionally stable, regardless of the load.
Convention Paper 5503

10:30 h
B3 A Comparison of Modular State-of-the-Art Switch Mode and Linear Audio Power Amplifiers – Darren Rose, Genelec OY, Iisalmi, Finland

Modern commercially available, compact, low power audio power amplifiers are mostly designed around one of three main technologies. These are integrated circuit class AB, thick film hybrid class AB, and switch mode power amplifier modules. The decision to use a particular technology is not only based on idealized performance specifications, but also on the performance under realistic operating conditions, and cost-to-performance considerations. In this study, the performance of each amplifier technology is studied in ideal and realistic operating conditions with two amplifier designs for each technology category. Regulated and unregulated power supplies are used, in combination with ideal resistive and real-life complex impedance loudspeaker loads. For a fixed nominal supply voltage, the value of the different technologies with regard to noise, distortion and continuous output power is discussed. This results in an analysis of the cost effectiveness, or value, of currently competing technologies for high quality, low power, compact audio power amplifiers.
Convention Paper 5504