Constant voltage power supply circuit

Abstract

A disclosed constant voltage power supply circuit ( 1 ) has an input terminal (Vdd), an output terminal (Vout), a constant voltage power supply unit ( 2 ) that generates a constant voltage (Vo 1 ) with a ripple voltage (Vri), and a ripple removing circuit unit ( 3 ) for removing the ripple voltage so that a constant voltage (V 1 ) without the ripple voltage is output at the output terminal (OUT). The ripple removing circuit unit comprises a resistor (R 1 ) connected between the constant voltage power supply unit and the output terminal; a ripple voltage detection circuit unit ( 5 ) for detecting the ripple voltage and outputting a signal depending on the detected ripple voltage; and a current circuit unit ( 6, 7 ) for receiving the signal from the ripple voltage detection circuit unit and supplying a current (io 1 ) to the output terminal or absorbing a current (io 2 ) from the resistor in response to the received signal, so as to cancel the ripple voltage at the output terminal.

1 - 8 . (canceled) 
   
   
       9 . A constant voltage power supply circuit comprising:
 a constant voltage power supply unit configured to generates a constant voltage; and   a ripple removing circuit unit for removing a ripple voltage in said constant voltage generated by said a constant voltage power supply unit, so that an output voltage without the ripple voltage is output at an output terminal.   
   
   
       10 . The constant voltage power supply circuit of  claim 9 , wherein the ripple removing circuit unit includes
 a resistor connected between the constant voltage power supply unit and the output terminal;   a ripple voltage detection circuit unit for detecting the ripple voltage and outputting an output signal depending on the detected ripple voltage; and   a current circuit unit configured to receive said output signal from the ripple voltage detection circuit unit and supplying a current to the output terminal in response to the received signal.   
   
   
       11 . The constant voltage power supply circuit of  claim 10 , wherein the current supplied to the output terminal cancels the ripple voltage at the output terminal. 
   
   
       12 . The constant voltage power supply circuit of  claim 9 , wherein the ripple removing circuit unit includes
 a resistor connected between the constant voltage power supply unit and the output terminal;   a ripple voltage detection circuit unit for detecting the ripple voltage and outputting an output signal depending on the detected ripple voltage; and   a current circuit unit configured to receive said output signal from the ripple voltage detection circuit unit and absorb a current from the resistor in response to the received signal.