1. Field of the Invention
An embodiment of the present invention relates to a temperature sensor circuit including a semiconductor element and a semiconductor device including the temperature sensor circuit.
2. Description of the Related Art
A temperature sensor circuit includes a sensor which converts temperature data into an electric signal (sensor signal) and circuits for processing the sensor signal output from the sensor. In the case where a temperature sensor circuit is formed in a semiconductor integrated circuit, not a resistance thermometer bulb, a thermistor, a thermocouple, or the like but a sensor utilizing the influence of temperature of a diode is generally used.
Specifically, in the case of a temperature sensor circuit including a diode as a sensor, with the diode where a proportion of variations in electrical characteristics depending on the temperature (i.e., the proportion is influence of temperature and the proportion is also called temperature dependence) is large, temperature data of an object to be detected can be obtained using a forward voltage generated when a forward current is constant or a forward current when a forward voltage is constant. For example, a forward voltage generated when a constant forward current flows from a constant current source to the diode is lower when the temperature of the diode is higher, and is higher when the temperature of the diode is lower. Thus, the forward voltage of the diode depends on the temperature of the diode.
Patent Document 1 below discloses a temperature sensor including a resistor serving as a current control element and a diode serving as a sensor element; the resistor and the diode are connected between a power source VDD and ground GND.