US 11,870,400 B2
Class-D amplifying system and class-D amplifier circuit
Yi-Kuang Chen, Taichung (TW)
Assigned to RICHTEK TECHNOLOGY CORPORATION, Zhubei (TW)
Filed by Richtek Technology Corporation, Zhubei (TW)
Filed on Feb. 21, 2022, as Appl. No. 17/676,594.
Claims priority of application No. 110109061 (TW), filed on Mar. 15, 2021.
Prior Publication US 2022/0294396 A1, Sep. 15, 2022
Int. Cl. H03F 1/26 (2006.01); H03F 3/217 (2006.01); H03F 1/02 (2006.01)
CPC H03F 1/26 (2013.01) [H03F 1/0216 (2013.01); H03F 3/217 (2013.01); H03F 2200/372 (2013.01)] 36 Claims
OG exemplary drawing
 
1. A class-D amplifying system, comprising:
an input current type digital-to-analog converter (DAC), which is configured to operably convert a digital input signal, so as to generate an analog input signal at an analog input node;
a class-D amplifier circuit, which is coupled to the input current type DAC, wherein the class-D amplifier circuit includes:
a pulse width modulator, which is configured to operably generate a pulse width modulation (PWM) signal according to the analog input signal;
an H-bridge (full-bridge) power stage circuit, which is configured to operably generate an output signal according to the PWM signal, wherein the H-bridge power stage circuit is powered by a driving power supply; and
a feedback device, which is configured to operably feedback the output signal to the analog input node; and
a common mode (CM) current type digital-to-analog converter (DAC), which is coupled to the analog input node and which is configured to operably generate a CM adjustment current, wherein the CM adjustment current is correlated with one of the following parameters:
(1) a CM voltage of the analog input signal;
(2) the driving power supply; or
(3) the CM voltage of the analog input signal and the driving power supply;
wherein the CM current type DAC is configured to operably determine which of the parameters (1)-(3) that the CM adjustment current is to be correlated with according to one of the following states:
(A) a level state of the output signal;
(B) a level state of the PWM signal; or
(C) the level state of the output signal and the level state of the PWM signal;
wherein in an adaptive voltage position mode, the CM adjustment current is further correlated with a predetermined voltage difference, wherein the predetermined voltage difference is correlated with an amplitude of the output signal, a slope of the output signal and a resistance of the feedback device, wherein in the adaptive voltage position mode, a target value of the CM voltage of the analog input signal is synchronous with and correlated with a CM voltage of the output signal.