D class amplifier and control method thereof

Abstract

The invention relates to a D class amplifier which comprises a first comparator, a second comparator, a third comparator, a switching circuit and a driving circuit and is characterized in that the first comparator compares a sawtooth wave signal and a first voltage to generate a first signal; the second comparator compares the sawtooth wave signal and a second voltage to generate a second signal; the third comparator is provided with a first input and a second input, the first input of the third comparator is connected with an input signal, and the third comparator compares signals on the first input and the second input to generate a pulse-width modulation (PWM) signal; the switching circuit switches the sawtooth wave signal, the first voltage or the second voltage to the second input of the third comparator according to the first signal and the second signal; and the driving circuit generates a third signal according to one of the first signal and the second signal and the PWM signal to drive a load on the output of the D class amplifier.

Description

technical field [0001] The invention relates to a class D amplifier, in particular, a class D amplifier with minimum pulse and its control method. Background technique [0002] figure 1 The known class D amplifier 10 includes a control circuit 12 and an output stage 14. The control circuit 12 generates output signals VOUTP and VOUTN according to an input signal AudioIN, and the output signals VOUTP and VOUTN switch the PMOS transistors P1 and VOUTN in the output stage 14. P2 and NMOS transistors N1 and N2 to drive the load. In order to avoid a short circuit of the output stage 14 due to the short duty cycle of the output signal VOUTP or VOUTN, a minimum pulse mechanism may be provided to make the output signal VOUTP or VOUTN have a minimum pulse width. [0003] There are two known minimum pulse generation methods, one is as described in U.S. Patent No. 6,262,632, which uses the time delay difference of two input channels to generate a oneshot pulse (oneshot pulse), and the...

AI Technical Summary

Problems solved by technology

However, in the aforementioned method, when the amplitude of the input signal AudioIN is higher than the amplitude of the internal switching waveform, the minimum pulse cannot be generated, thus causing the output stage 14 to continue to be short-circuited

In addition, the minimum pulse will also cause non-linear phenomena

[0004] Therefore, there are above-mentioned inconveniences and problems in the known class D amplifiers.

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