Circuit for class D amplifier

Abstract

A class-D switching amplifier is disclosed. The class-D switching amplifier includes two control circuits, a load, and six switching devices. The load is coupled to the six switching devices. The first and the second control circuits provide a first and a second PWM pulse respectively. Each of the first and second switching devices has a first terminal coupled to a first voltage level, a second terminal coupled to the load, and a control terminal coupled to the first control circuit. Each of the third, fourth, fifth, and sixth switching devices has a first terminal coupled to a second voltage level, and a second terminal coupled to the load. The control terminals of the third and fourth switching devices are coupled to the first control circuit. The control terminals of the fifth and sixth switching devices are coupled to the second control circuit.

Description

technical field [0001] The invention relates to a class D amplifier circuit, in particular to a class D amplifier circuit whose internal circuit can modulate circulating current to reduce signal distortion. Background technique [0002] The carrier frequency of the class D amplifier, that is, the duty cycle of the PWM signal generator, is generally between 200 kHz and 2 MHz. At the highest output power, the signal is high for the entire cycle; at 50% of the maximum output power, the signal is high for half a cycle, and the level decreases linearly with the desired audio level. Since the output power is proportional to the output pulse width, the degree of signal distortion is also proportional to the error, which is the error between the effective pulse width and the required pulse width. In the case of a large signal, although the error is small, in the case of a small input signal, the error is large. For the traditional CMOS technology used in class D amplifiers, the mi...

AI Technical Summary

Problems solved by technology

However, as mentioned earlier, the current process capability only provides a minimum pulse width of about 50 nanoseconds, which obviously cannot meet the undistorted standard for human hearing.

In a general Class D amplifier, the uncorrected large signal distortion is between -35dB and -45dB, but the distortion rate also increases rapidly as the signal level decreases

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