Reference voltage generating circuit method of generating reference voltage and integrated circuit including the same

A temperature sensor, comprising:

• a reference voltage generating circuit configured to generate first and second reference voltages which are constant regardless of temperature;
• a first voltage generating circuit configured to generate a first voltage proportional to the temperature, based on the second reference voltage;
• and
• an analog-to-digital converter (ADC) configured to produce a digital temperature signal, based on the first reference voltage and the first voltage,
• wherein the reference voltage generating circuit comprises
• an operational amplifier having a first input terminal connected to a first node, and having a second input terminal connected to a second node,
• a first transistor connected between a ground terminal and the first node, wherein a first current flows in the first transistor,
• a second transistor connected to the ground terminal,
• a first variable resistor connected between the second transistor and the second node, the first variable resistor having a first resistance value that is adjustable, and
• a current source circuit configured to provide a first reference current to a third node based on an output voltage of the operational amplifier,
• wherein the third node is connected to the first node and the third node is configured to output the first and second reference voltages based on a first node voltage of the first node and a voltage across the first variable resistor.

An integrated circuit, comprising:

• a reference voltage generating circuit configured to provide a reference voltage;
• and
• an internal circuit configured to operate based on the reference voltage,
• wherein the reference voltage generating circuit comprises
• an operational amplifier comprising a first input terminal connected to a first node and a second input terminal connected to a second node,
• a first transistor connected between a ground terminal and the first node, wherein a first current flows in the first transistor,
• a second transistor connected to the ground terminal,
• a first variable resistor connected between the second transistor and the second node, the first variable resistor having a first resistance value that is adjustable, and
• a current source circuit configured to provide a first reference current to a third node based on an output voltage of the operational amplifier,
• wherein the third node is connected to the first node and the third node is configured to output the reference voltage based on a voltage of the first node and a voltage across the first variable resistor,
• wherein the current source circuit is further configured to provide a second reference current to a fourth node based on the output voltage of the operational amplifier, and
• wherein the fourth node is connected to the second node, and the fourth node and the third node are different respective nodes that are not directly connected to each other.