Reduction in spectral peaks of DC-DC converters using chaos-modulated clock

Electronic power converters are notorious sources of electromagnetic interference, and suppression of EMI is a major issue in switched-mode power converter design. A substantial part of the manufacturing cost of power converters for critical applications involves designing filters to conform to the varying EMI norms for the various domains, such as defence, aerospace etc. We propose a method of EMI reduction using spectral modification through chaotic modulation. The converter is operated in a regular periodic regime, and then the timing signal (the clock or the ramp waveform) is modulated with a chaotic signal. We have designed and fabricated a chaos-modulated clock circuit that can be easily implemented in CMOS. We have shown, by both simulation and experiment, that this results in a reduction of spectral peaks and a consequent spreading of the spectrum - which can be precisely controlled by adjusting the gain of the chaotic waveform. This scheme can thus eliminate filters and screens, or can at least reduce their size significantly

Development of novel low noise switch-mode power supply designs for high fidelity audio power amplifiers.

Today, linear power supplies are widely used to provide the supply voltage rail to an audio amplifier and are considered bulky, inefficient and expensive due to the presence of various components. In particular, the typical requirements of linear designs call for physically large mains transformers, energy storage/filtering inductors and capacitors. This imposes a practical limit to the reduction of weight in audio power systems. In order to overcome these problems, Switch-mode Power Supplies (SMPS) incorporate high speed switching transistors that allow for much smaller power conversion and energy storage components to be employed. In addition the low power dissipation of the transistors in the saturated and off states results in higher efficiency, improved voltage regulation and excellent power factor ratings. The primary aim of this research was to develop and characterize a novel low noise switch mode power supply for an audio power amplifier. In this thesis, I proposed a novel balancing technique to optimize the design of SMPS that elevate the performance of converter and help to enhance the efficiency of power supply through high speed switching transistors. In fact, the proposed scheme mitigates the noise considerably in various converter topologies through different mechanisms. To validate the proposed idea, the technique is applied to different converters e.g; PFC boost converter, flyback converter and full-bridge converter. The performance of audio amplifier is evaluated using designed SMPS to compare with existing linear power supply. On the basis of experimental results, the decision has been made that the proposed balanced SMPS solution is as good as linear solution. Due to novelty and universality of balancing technique, it can provide a new path for researchers in this field to utilize the SMPS in all other audio devices by further enhancing its efficiency and reducing system noise