Digital Tri-State Class-D Amplifier

Abstract

The invention discloses a digital tri-state class-D amplifier, which comprises two signal channels, wherein a channel 1 is used for outputting a pulse width modulating signal; a channel 2 is used for outputting a fundamental frequency square signal; two paths are amplified respectively through a power amplifier, and are synthesized into a tri-state pulse width modulating signal; and the tri-state pulse width modulating signal passes through a band pass circuit to obtain a fundamental frequency sine signal. According to the digital tri-state class-D amplifier, a pulse width modulating way in which less than nine times of harmonic components are lowest is computed according to a Fourier series combination principle in a trigonometric function form for the tri-state pulse width modulating signal, two-state changes of two paths of differential fundamental frequency square signals of the conventional class-D amplifier are designed into the tri-state change of the tri-state pulse width modulating signal, and meanwhile, longer idle state time is achieved in comparison to an ordinary tri-state class-D amplifier, so that the loss of a power switch is lower, the output power efficiency is higher, the band pass circuit and reasonable board wiring are combined, and the EMI (Electro-Magnetic Interference) problem of the conventional class-D amplifier is solved more effectively under the condition of much lower modulating frequency. Meanwhile, a system power supply voltage detecting circuit is combined, and the same power output under different power supply voltages can be obtained by only regulating the modulating pulse width of the channel 1, so that the running reliability and stability of the system are ensured.

Description

technical field [0001] The invention relates to the field of amplifiers in communication systems and other electronic systems, in particular to a digital three-state class D amplifier and an application method thereof. Background technique [0002] Traditional class-D amplifiers are usually designed based on the principle of pulse width modulation (PWM). Channel 1 and channel 2 obtain two reverse square wave fundamental frequency signals from the transformer and input them to the power amplifier device, because of its fast switching time and close rail-to-rail rail swing makes this type of amplifier very efficient. However, this characteristic makes this type of amplifier have a wide output spectrum. In practical applications, due to the bandwidth limitation of the external filter, it is difficult to suppress the harmonic components of the harmonics below the 9th order, which makes EMI have a huge impact. more obvious. Therefore, there is an urgent need for a new type of a...

AI Technical Summary

Problems solved by technology

[0003] The technical problem to be solved by the present invention is to provide a new type of amplifier to solve the current advantages of ensuring the high efficiency of the traditional Class D amplifier and improve the EMI problem, and further promote the development of communication systems and other electronic systems

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