Modelling and analysis of a high-performance Class D audio amplifier using unipolar pulse-width-modulation

A "battery connect" compatible class D (switching) amplifier which is fully integrated in a 90-nm digital CMOS process is presented. The integration of the amplifier requires no additional masks, processing, or cost. This paper includes a brief description of the circuit techniques that enable direct battery (2.7-5.4 V) connection and allow support >6.7 V/sub P2P/ (700 mW into 8 /spl Omega/) output swing from a 4.2-V supply using devices that operate solely with low gate voltages. The achieved S...

Voltage feedback is frequently used in class-D switching audio power amplifiers. This paper discusses the design and implementation of a low-cost filterless class-D, unipolar pulse-width modulation switching audio amplifier having a multi-loop voltage feedback scheme. Classical frequency-compensation techniques are used to design and stabilize the three voltage feedback loops implemented in this application. This design method proves to be a cost-effective solution for designing high-fidelity (h...

An enhanced sampling process which can be used to reduce spectral distortion in the output of digital pulse width modulated class D amplifiers is presented. This process arises from a generalisation of the concepts of natural and uniform sampling and can be adjusted such that the spectra produced by the process can take a number of forms for the same signal. Analytical expressions for the spectra produced by the sampling process are derived for both single and double sided modulation. The perfor...

High-efficiency speakers significantly improve electrical to sound power conversion efficiency by reducing the power dissipation over the speaker coil. However, they require some equalization of the input signal. In this paper, a new driving technique based on a pulsewidth-modulation switching amplifier is presented. This exploits a double voltage/current feedback to obtain automatic equalization. Furthermore, the double feedback allows the output resonant filter to be included in the feedback p...

This paper presents a single chip class D amplifier with 2.5 W output power and 86% efficiency with an 8 ohm load. This chip uses a pulsed width modulation scheme that eliminates the output filter. It operates with a 2.5 V to 6.5 V supply voltage in a 7 V, 1.2 /spl mu/m, double-poly, triple-metal BiCMOS process. It has an area of 1.5 /spl times/ 1.5 mm/sup 2/ and it achieves a THD as low as 0.04%, with a flatband response between 20 Hz and 20kHz.

A fully integrated overcurrent protection system is presented suitable for application in integrated class-D audio power amplifiers. Accurate overcurrent detection is used based on parallel measurement of the voltage drop across the DMOS power transistors. A logic circuit enables continuous current limiting during overload situations. Actual short circuits can be distinguished from load impedance minima using a simple short-circuit discrimination method.

Linear and switching techniques are currently adopted to implement current-mode power stages. Pulsewidth modulation (PWM) is usually employed with the switching technique for both industrial and audio applications. In this paper, the Sigma-Delta modulation is considered as an alternative to the PWM in devising a switching current-mode power stage suitable for audio amplification. The proposed modulator is analyzed and simulated. The whole system was realized on an experimental breadboard. The re...

In this paper, we investigate two important and practical design parameters for the design of low-voltage low-power class D amplifiers that may affect the Total Harmonic Distortion (THD): the linearity of the carrier waveform and the impedance of the output stage. By means of a novel mathematical analysis method to model the carrier non-linearity, we show that this non-linearity should be mitigated to achieve low THD. Our mathematical analysis also provides an insight to the degree of non-linear...

Class D amplifiers are becoming the most feasible solution for embedded audio application. However, distortions due to the non-linear nature of switching stage are the main drawback for this amplifier topology. This paper discusses the design and implementation of high fidelity audio class D using sliding mode control scheme. This design method proves to be a cost effective solution for industrial circuit. Experimental IC results, using commercial 0.13 mum CMOS technology, verified the theoretic...