Patent ID: 8334682

Claim:
A buck converter with internal ripple compensation, comprising: a comparator, comprising a first input terminal, a second input terminal, and an output terminal, for comparing signals received by the first input terminal and the second input terminal to generate a comparison result; a constant-on-time trigger, coupled to the output terminal of the comparator, for generating a trigger control signal according to the comparison result; a pre-driver, coupled to the constant-on-time trigger, for generating a first pre-driving signal and a second pre-driving signal according to the trigger control signal; a high side switch, coupled to the pre-driver and a first node; a low side switch, coupled to the pre-driver and the first node; an output module, coupled between the first node and a signal output end; and a ripple compensation circuit, coupled to the high side switch, the low side switch, the first node, and the comparator for generating a compensation signal outputted to the comparator; wherein the ripple compensation circuit comprises: a current sensing unit, coupled to the first node, for sensing a current passing through the low side switch while the low side switch is in an on state and generating a sensing voltage accordingly; a first sample-and-hold circuit, coupled to the current sensing unit and a first terminal of the low side switch, for sampling and holding the sensing voltage detected by the current sensing unit to generate a first voltage; a second sample-and-hold circuit, coupled to the first sample-and-hold circuit and a first terminal of the high side switch, for sampling and holding the first voltage to generate a second voltage; a first voltage-to-current conversion circuit, comprising a first input terminal coupled to the second sample-and-hold circuit, a second input terminal coupled to the first sample-and-hold circuit, and an output terminal coupled to the first input terminal of the comparator, for generating a compensation current according to the first voltage and the second voltage; and a voltage adjusting unit, coupled to the output terminal of the first voltage-to-current conversion circuit and the first input terminal of the comparator, for generating the compensation signal outputted to the comparator according to a reference voltage and the compensation current.