Bandgap circuit

1 . A bandgap circuit comprising:

a load circuit arranged between an output terminal and a first power supply line;

an output transistor arranged between the output terminal and a second power supply line, and outputs a desired reference voltage in accordance with control voltage;

a control voltage generating circuit generating the control voltage applied to the output transistor; and

a filter arranged between the output transistor and the control voltage generating circuit.

2 . The bandgap circuit according to claim 1 , wherein

the control voltage generating circuit further comprises:

a first diode element having one end connected to the first power supply line;

a first resistor having one end connected to the other end of the first diode element;

a second diode element having one end connected to the first power supply line and having a different size than the size of the first diode element; and

a control voltage generating part generating the control voltage based on a first potential generated at the other end of the first resistor and a second potential generated at the other end of the second diode element.

3 . The bandgap circuit according to claim 2 , wherein the filter has a second resistor and a capacitor, the second resistor having one end connected to the control voltage generating part and the other end connected to a gate of the output transistor, and the capacitor being connected between the other end of the second resistor and the first power supply line or the second power supply line.

4 . The bandgap circuit according to claim 3 , wherein the control voltage generating part supplies substantially the same current to the first and second diode elements based on the first potential and the second potential, the control voltage generating part includes first and second transistors where control terminals are connected in common, and the control voltage is applied to the control terminals of the first and second transistors.

5 . The bandgap circuit according to claim 2 , wherein the control voltage generating part comprises:

a first transistor connected to the other end of the first resistor and the second power supply line;

a second transistor connected between the other end of the second diode element and the second power supply line; and

an amplifier having a non-inverting input terminal connected to the other end of the first resistor and an inverting input terminal connected to the other end of the second diode element, wherein

an output of the amplifier is applied to control terminals of the first and second transistors so that the amplifier outputs the control voltage.

6 . The bandgap circuit according to claim 2 , wherein the control voltage generating part further comprises first to fourth transistors including control terminals, sources, and drains, wherein

the first transistor has a control terminal and a drain connected in common and a source connected to the second power supply line,

the second transistor has a control terminal connected to the control terminal of the first transistor in common and a source connected to the second power supply line,

the third transistor has a control terminal and a drain connected in common, a source connected to the other end of the second diode element, and a drain connected to the drain of the second transistor,

the fourth transistor has a control terminal connected to the control terminal of the third transistor in common, a source connected to the other end of the first resistor, and a drain connected to the drain of the first transistor, and

the control voltage generating part outputs the voltage of the control terminals of the first and second transistors as the control voltage.

7 . The bandgap circuit according to claim 2 , wherein the control voltage generating part comprises:

a first transistor having a drain connected to the other end of the first resistor; and

a second transistor having a drain connected to the other end of the second diode element, wherein

the control voltage generating part forms a current mirror where a gate of the first transistor and a gate of the second transistor are connected in common.

8 . The bandgap circuit according to claim 7 , wherein

the control voltage generating part comprises an amplifier generating the control voltage supplied to gates of the first and second transistors based on a first potential generated at the other end of the first resistor and a second potential generated at the other end of the second diode element.

9 . The bandgap circuit according to claim 2 , wherein the control voltage generating part comprises:

a first transistor having a control terminal and a drain connected in common and a source connected to the second power supply line;

a second transistor having a control terminal connected to the control terminal of the first transistor in common and a source connected to the second power supply;

a third transistor having a control terminal and a drain connected in common, a source connected to the other end of the second diode element, and a drain connected to the drain of the second transistor; and

a fourth transistor having a control terminal connected to the control terminal of the third transistor in common, a source connected to the other end of the first resistor, and a drain connected to the drain of the first transistor, wherein

the control voltage generating part forms a current mirror where a gate of the first transistor and a gate of the second transistor are connected in common, and

the third and fourth transistors set values of current flowing in the first and second transistors and the output transistor based on the current generated according to a first potential generated at the other end of the first resistor and a second potential generated at the other end of the second diode element.