Single ended switching analog audio amplifier with dead zone

An audio amplifier of small size and high efficiency can cater to the needs of a market comprising computer multimedia, portable computers, hearing aid devices, and medical and military applications. With the switching audio amplifier, or Class D amplifier, it is possible to obtain high efficiency and small size, but with serious limitations on the quality of the audio signal. In this work, a full review of the state of the art of the Class D amplifier is presented, including the different attempts to minimize distortion. Special attention is given to the design of the audio amplifier with combined analog and switching amplifier technologies. This hybrid technique retains the high quality generated by analog amplifiers and the large-scale integration achievable with efficient switching techniques (Class AD). The Class AD amplifier is analyzed using nonlinear techniques based on the Hysteresis-Describing Function method. This analysis includes the effect of hysteresis and determines the distortion as a function of the instantaneous amplitude of the audio signal, with respect to the parameters of the system. The set of equations derived is a simple design tool that allows behavior prediction, component sizing, and distortion estimation.; A new topology for a single ended Class D amplifier that provides a dead zone is presented. The proposed inverter topology exhibits an overall increase in the efficiency for a wide range of the input signal. With this new inverter topology, it is possible to obtain zero output voltage without switching, thereby reducing the switching losses and the operating requirements of the analog amplifier that acts as an active filter.; The single ended switching analog audio amplifier with dead zone consists of two buck converters, one operating for the positive part and one for the negative part of the signal. Smooth transition between them is achieved through the analog amplifier. The selection between the two buck converters is performed by additional switches in the respective freewheeling of each buck converter. Since the singled-ended configuration requires only one analog amplifier to compensate for distortion, the system exhibits higher efficiency. In addition, this allows the speaker to be referenced to ground, which mitigates the effects of electromagnetic interference. The proposed system was simulated initially in a coarse and general model using PSPICE®, and later in a detailed and specific model using ICAP®. Simulation results guide the amplifier design. Finally, a laboratory prototype was built and tested. Experimental results have been promising yielding a distortion of 0.55% for a 1 kHz sinusoid and an efficiency of 80% for a 20W output using the designed prototype.