Temperature sensor circuit and display apparatus including the same

A temperature sensor circuit for measuring temperature inside a pixel of a display, the circuit comprising:

• a first thin film transistor;
• a second thin film transistor interconnected with the first thin film transistor;
• and
• a temperature measurement unit for measuring temperature based on an output voltage according to difference in off current between the first thin film transistor and the second thin film transistor,
• wherein the first thin film transistor and the second thin film transistor are different types of thin film transistors,
• wherein the first thin film transistor comprises a first drain terminal, a first gate terminal, and a first source terminal,
• wherein the second thin film transistor comprises a second drain terminal, a second gate terminal, and a second source terminal, and the second drain terminal is interconnected with the first drain terminal to form a connection portion,
• wherein the first thin film transistor and the second thin film transistor output an output voltage through the connection portion,
• wherein the first thin film transistor receives a first bias voltage (VPBIAS) through the first gate terminal,
• wherein the second thin film transistor receives a second bias voltage (VNBIAS) through the second gate terminal
• wherein the first thin film transistor is set to an off state based on the first bias voltage (VPBIAS),
• wherein the second thin film transistor is set to an off state based on the second bias voltage (VNBIAS),
• wherein the first bias voltage (VPBIAS) is a p-type bias voltage,
• wherein the second bias voltage (VNBIAS) is an n-type bias voltage,
• wherein the first gate terminal is connected to a source of the first bias voltage (VPBIAS),
• wherein the second gate terminal is connected to a source of the second bias voltage (VNBIAS),
• wherein the first thin film transistor comprises a p-type low-temperature polycrystalline silicon (LTPS) thin film transistor,
• wherein the second thin film transistor comprises an n-type oxide semiconductor thin film transistor,
• wherein the first drain terminal is connected to a source of a drain voltage,
• wherein the connection portion outputs the output voltage changed by the drain voltage and the temperature,
• wherein a change of the drain voltage changes the output voltage with the temperature and a voltage sensitivity,
• wherein the first thin film transistor and the second thin film transistor have different channel lengths and channel widths, and a channel length of the first thin film transistor is shorter than a channel length of the second thin film transistor, a channel width of the second thin film transistor is greater than a channel width of the first thin film transistor, and the channel width ratio of the second thin film transistor to the first thin film transistor is 10:1.