Sigma-Delta type power amplifier and modulation method thereof

Abstract

This invention relates to a sigma-Delta power amplifier and its modulation method, which plugs a gain controller between a sigma-Delta modulator and an output stage to amply or reduce the signal provided to the output stage by the modulator according to a signal related to the input signal and then provides it to the output level so as to reduce the transformation rate of the modulation.

Description

Sigma-Delta Power Amplifier and Its Modulation Method technical field The present invention relates to a power amplifier, in particular to a sigma-delta power amplifier. Background technique The low efficiency of traditional audio signal power amplifiers results in high heat generation, and a large heat sink must be used to help dissipate heat, so the physical device is bulky. In recent years, in order to reduce the size of the amplifier, high-efficiency design schemes have been proposed, and the most common way is to use a class D (class D) amplifier, also known as a switching amplifier (switching amplifier). The working principle of this type of amplifier is to convert an analog or digital input signal into a two-level output signal using a high-frequency modulation method, and then send the second-level signal to the power stage. To switch the power switch (powerswitch) in the power stage. The heat generated by these power switches is extremely low, so the efficiency ...

AI Technical Summary

Problems solved by technology

One of the disadvantages of this system is that the high-order sigma-delta modulator will be less stable due to the introduction of quantizer hysteresis, so the magnetic values ​​in the look-up table 28 must be preset for each range of the input signal Vin. optimal value of hysteresis

In addition, because the hysteresis of the quantizer 24 is discrete, it is easy to cause other problems

Furthermore, the quantizer 24 must use a variable hysteresis device, the circuit is more complicated and more expensive, and the increased digital converter 26 and look-up table 28 make the chip larger and increase the cost

There is another problem with the power amplifier 10 of FIG. 1. Because the power stage 18 is not linear, the negative feedback from the output of the quantizer 16 does not accurately represent the true output signal Vout, so the error introduced will make the amplifier 10 performance degradation of

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