Patent ID: 7795854
Filing Date: 2010-09-14
Classification: H02M

Abstract:
1. A voltage regulating circuit, comprising: an error signal generator, having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal and the second input terminal of the error signal generator respectively receive a reference voltage signal and a feedback signal, and the output terminal of the error signal generator outputs an error signal; a comparator, having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal receives the error signal, the second input terminal receives a comparing signal, and the output terminal thereof generates a pulse width modulation signal; a switch unit, coupled to the output terminal of the comparator for regulating an input voltage signal and thereby generating an output voltage signal according to the pulse width modulation signal; a low-pass filter, coupled to the switch unit for filtering the high frequency of the output voltage signal and generating the feedback signal; a modulating unit, having a first terminal and a second terminal, wherein the first terminal of the modulating unit is coupled to the low-pass filter and the second input terminal of the error signal generator, and the second terminal of the modulating unit is coupled to the output terminal of the error signal generator for regulating the transient voltage of the output voltage signal; and a first compensating unit, having a first terminal and a second terminal, wherein the first terminal is coupled to the second input terminal of the error signal generator, and the second terminal thereof is coupled to the output terminal of the error signal generator for compensating the error signal, wherein the first compensating unit comprises: a first resistor, having a first end and a second end, wherein the first end is coupled to the second input terminal of the error signal generator; a first capacitor, having a first terminal and a second terminal, wherein the first terminal is coupled to the second end of the first resistor, and the second terminal thereof is coupled to the output terminal of the error signal generator; and a second capacitor, having a first terminal and a second terminal, wherein the first terminal is coupled to the first end of the first resistor, and the second terminal thereof is coupled to the second terminal of the first capacitor.