Patent ID: 7602236

Claim:
A band gap reference voltage generation circuit comprising: an operation amplifier for outputting a uniform voltage in accordance with a reference voltage input to an inversion terminal and a non-inversion terminal; a first-type first transistor for outputting a power source voltage in accordance with a power down signal; a first-type second transistor for outputting a bias current corresponding to the uniform voltage in response to the power source voltage from the first-type first transistor; a reference voltage circuit for supplying a reference voltage to the inversion terminal and the non-inversion terminal in response to the bias current; a second-type first transistor for supplying a base voltage to an output port of the operation amplifier in accordance with the power down signal; a start up circuit for driving the bandgap reference circuit during power up; a first node between the first-type second transistor and the reference voltage circuit; an output terminal connected to the first node; and a noise filter circuit connected to the power source voltage, the base voltage, and the first node to remove RF noise of an output voltage of the first node and to output the output voltage of the first node to the output terminal, wherein the noise filter circuit comprises: a first-type sixth transistor connected between the first node and the output terminal; a first-type seventh transistor connected between the power source voltage and the output terminal; and a second-type sixth transistor controlled in accordance with the power down signal and connected between the output terminal and the base voltage; wherein the first-type sixth transistor functions as a capacitor and includes a gate terminal connected to the base voltage, a source terminal connected to the first node, and a drain terminal connected to the output terminal, and the first-type seventh transistor functions to provide an impedance and includes a gate terminal connected to the output terminal and source and drain terminals connected to the power source voltage.