Constant output reference voltage circuit

1. A voltage reference circuit comprising: a first MOS transistor including a source terminal connected to a first power supply terminal; a second MOS transistor including a source terminal connected to the first power supply terminal and a gate terminal connected to a gate terminal of the first MOS transistor, the second MOS transistor having an absolute value of a threshold value higher than an absolute value of a threshold value of the first MOS transistor; a current mirror circuit flowing a current based on a difference between the absolute values of the threshold values of the first MOS transistor and the second MOS transistor; a third MOS transistor flowing the current of the current mirror circuit; a fourth MOS transistor having an absolute value of a threshold value higher than an absolute value of a threshold value of the third MOS transistor and flowing the current of the current mirror circuit, wherein the voltage reference circuit outputs, as a reference voltage, a constant voltage based on the absolute values of the threshold values of the third MOS transistor and the fourth MOS transistor; wherein the current mirror circuit includes: a fifth MOS transistor including a drain terminal and a gate terminal connected to a drain terminal of the first MOS transistor; a sixth MOS transistor including a gate terminal connected to the gate terminal of the fifth MOS transistor and a drain terminal connected to the gate terminal and a drain terminal of the second MOS transistor; a seventh MOS transistor including a gate terminal connected to the gate terminal of the fifth MOS transistor and a drain terminal connected to a drain terminal of the third MOS transistor; an eighth MOS transistor including a gate terminal connected to the gate terminal of the fifth MOS transistor and a drain terminal connected to a drain terminal of the fourth MOS transistor; and a resistor including one terminal connected to a gate terminal of the third MOS transistor and another terminal connected to a gate terminal of the fourth MOS transistor, wherein the voltage reference circuit outputs, as a reference voltage, a constant voltage based on a voltage at both ends of the resistor.

2. A voltage reference circuit comprising: a first MOS transistor including a source terminal connected to a first power supply terminal; a second MOS transistor including a source terminal connected to the first power supply terminal and a gate terminal connected to a gate terminal of the first MOS transistor, the second MOS transistor having an absolute value of a threshold value higher than an absolute value of a threshold value of the first MOS transistor; a current mirror circuit flowing a current based on a difference between the absolute values of the threshold values of the first MOS transistor and the second MOS transistor; a third MOS transistor flowing the current of the current mirror circuit; wherein the current mirror circuit includes: a fourth MOS transistor including a drain terminal and a gate terminal connected to a drain terminal of the first MOS transistor; and a fifth MOS transistor including a gate terminal connected to the gate terminal of the fourth MOS transistor and a drain terminal connected to a gate terminal and a drain terminal of the third MOS transistor, wherein the third MOS transistor is configured to include a gate terminal connected to the gate terminal of the second MOS transistor and a source terminal connected to a drain terminal of the second MOS transistor, so that the voltage reference circuit outputs the reference voltage from a connecting point of the source terminal of the third MOS transistor and the drain terminal of the second MOS transistor; and wherein the voltage reference circuit outputs, as a reference voltage, a constant voltage based on the absolute values of the threshold values of the third MOS transistor and the second MOS transistor.