Switching regulator and method for eliminating beat oscillation

Abstract

The present invention discloses a switching regulator eliminating beat oscillation, comprising: a first transistor, a second transistor, and an inductor connected to a common node, wherein the first and second transistors operate to convert an input voltage to an output voltage; a comparator comparing a voltage signal with a saw tooth wave to generate a control signal controlling at least one of the first and second transistors; a feedback loop obtaining a feedback signal from the output voltage and generating the voltage signal according to the feedback signal; and an inductorless filter circuit located in the feedback loop for filtering a predetermined frequency band.

1 . A switching regulator eliminating beat oscillation, comprising:
 a first transistor, a second transistor, and an inductor connected to a common node, wherein the first and second transistors operate to convert an input voltage to an output voltage;   a comparator comparing a voltage signal with a saw tooth wave to generate a control signal controlling at least one of the first and second transistors;   a feedback loop obtaining a feedback signal from the output voltage and generating the voltage signal according to the feedback signal; and   an inductorless filter circuit located in the feedback loop for filtering a predetermined frequency band.   
     
     
         2 . The switching regulator of  claim 1 , wherein the predetermined frequency band including frequencies in the vicinity of a frequency of the saw tooth wave. 
     
     
         3 . The switching regulator of  claim 1 , wherein the inductorless filter circuit includes:
 a resistor coupled between an input and an output of the inductorless filter circuit, and a capacitor and an inductor equivalent circuit connected in series between the output of the inductorless filter circuit and ground.   
     
     
         4 . (canceled) 
     
     
         5 . The switching regulator of  claim 1 , wherein the inductorless filter circuit includes a high-pass filter circuit and a low-pass filter circuit. 
     
     
         6 . The switching regulator of  claim 5 , wherein the high-pass filter circuit and low-pass filter circuit are electrically connected in series or in parallel. 
     
     
         7 . The switching regulator of  claim 5 , wherein the order of the high-pass filter circuit is greater than or equal to 1. 
     
     
         8 . The switching regulator of  claim 5 , wherein the order of the low-pass filter circuit is greater than or equal to 1. 
     
     
         9 . A method for eliminating beat oscillation in a switching regulator comprising:
 providing a switching regulator, the switching regulator including a first transistor, a second transistor, and an inductor connected to a common node;   operating the first and second transistors to convert an input voltage to an output voltage;   obtaining a feedback signal from the output voltage, and generating a voltage signal according to the feedback signal;   comparing the voltage signal with a saw tooth wave to generate a control signal controlling at least one of the first and second transistors; and   filtering a predetermined frequency band without an inductor during the process of obtaining the feedback signal from the output voltage and generating the voltage signal according to the feedback signal.   
     
     
         10 . The method of  claim 9 , in which the predetermined frequency band includes frequencies in the vicinity of a frequency of the saw tooth wave. 
     
     
         11 . The method of  claim 9 , wherein the step of filtering a predetermined frequency band without an inductor includes: providing an inductorless filter circuit, which includes: a resistor coupled between an input and an output of the inductorless filter circuit, and a capacitor and an inductor equivalent circuit connected in series between the output of the inductorless filter circuit and ground. 
     
     
         12 . (canceled) 
     
     
         13 . The method of  claim 9 , wherein the step of filtering a predetermined frequency band without an inductor includes: performing high-pass filtering and low-pass filtering. 
     
     
         14 . The method of  claim 13 , wherein the order of the high-pass filtering is greater than or equal to 1. 
     
     
         15 . The method of  claim 13 , wherein the order of the low-pass filtering is greater than or equal to 1.