Thin-film semiconductor device, circuitry thereof, and apparatus using them

1. A thin-film semiconductor device comprising:

a temperature sensor formed of a first thin-film semiconductor and sensing a temperature as current; and

a current-voltage converter formed of a second thin-film semiconductor and having temperature dependence in which its current-voltage characteristic is different from that of said temperature sensor;

wherein a temperature sensed by said temperature sensor is converted to a voltage by said current-voltage converter;

wherein said temperature sensor comprises a thin-film semiconductor layer, a gate electrode applying a gate voltage to said thin-film semiconductor layer, and a drain electrode and a source electrode conducting an electric current to said thin-film semiconductor layer, wherein said drain electrode or said source electrode is electrically short-circuited with said gate electrode; and

wherein the drain electrode or the source electrode of a first thin-film transistor of said current-voltage converter is connected to the drain electrode or the source electrode of said temperature sensor.

2. The thin-film semiconductor device according to claim 1 , wherein said current-voltage converter comprises said first thin-film transistor comprising a thin-film semiconductor layer, a gate electrode applying a gate voltage to said thin-film semiconductor layer and connected to a source of predetermined control voltage, and a drain electrode and a source electrode conducting an electric current to said thin-film semiconductor layer.

3. The thin-film semiconductor device according to claim 2 , wherein at the current-voltage conversion of said first thin-film transistor, said gate voltage is equal to or larger than three times the threshold voltage of said thin-film transistor.

4. The thin-film semiconductor device according to claim 2 , wherein at the current-voltage conversion of said first thin-film transistor, said gate voltage is a voltage giving a drain current saturation region of said thin-film transistor.

5. The thin-film semiconductor device according to claim 4 , further comprising a controller controlling said gate voltage to a predetermined value when converting an electric current sensed by said temperature sensor to a voltage.

6. The thin-film semiconductor device according to claim 2 , wherein said temperature sensor comprises a second thin-film transistor comprising a thin-film semiconductor layer, a gate electrode applying a gate voltage to said thin-film semiconductor layer, and a drain electrode and a source electrode conducting an electric current to said thin-film semiconductor layer.

7. The thin-film semiconductor device according to claim 6 , wherein the gate voltage of said temperature sensor and the gate voltage of said current-voltage converter have different values.

8. The thin-film semiconductor device according to claim 1 , wherein said temperature sensor is a pn junction diode formed of a third thin-film semiconductor.

9. The thin-film semiconductor device according to claim 6 , further comprising a first voltage source applying a first gate voltage to said temperature sensor within a first voltage range wherein a drain current of said temperature sensor has relatively high temperature dependence, and a second voltage source applying a second gate voltage to said current-voltage converter within a second voltage range wherein a drain current of said current-voltage converter has relatively low temperature dependence.

10. The thin-film semiconductor device according to claim 6 , further comprising a first voltage source applying a first gate voltage to said temperature sensor within a first voltage range wherein a drain current of said temperature sensor has relatively high temperature dependence, and a second voltage source applying a second gate voltage to said current-voltage converter within a second voltage range wherein a drain current of said current-voltage converter has opposite temperature dependence to that of said temperature sensor.

11. An RF-ID device which performs identification using a radio frequency, the RF-ID device incorporating the thin-film semiconductor device according to claim 1 .

12. A biochip or a DNA chip which incorporates the thin-film semiconductor device according to claim 1 .