Pin-compatible infrared light detector having improved thermal stability
An infrared light detector including at least one sensor chip that has a layer element that is produced from a pyroelectrically sensitive material and further has a base electrode and a head electrode, to which the layer element is connected for tapping electric signals generated in the layer element by irradiation of the at least one sensor chip with light. The detector further includes a transimpedance amplifier for amplifying the signals with an operational amplifier, which is asymmetrically operated by a supply voltage source having a positive supply voltage and to the inverting input of which the base electrode is connected. At the voltage supply source, a voltage divider connected to ground is provided with a partial node, to which a partial voltage that is smaller than the supply voltage is applied and which is electrically coupled to the non-inverting input and to the head electrode.
1. An infrared light detector comprising:
at least one sensor chip ( 3 , 4 ) that includes a layer element ( 5 , 8 ) made of a pyroelectrically sensitive material, a base electrode ( 6 , 9 ) and a head electrode ( 7 , 10 ),
wherein the layer element ( 5 , 8 ) is connected to the base electrode ( 6 , 9 ) and the head electrode ( 7 , 10 ) to tap an electrical signal generated in the layer element ( 5 , 8 ) as a result of light ( 2 ) radiation applied to the base electrode ( 6 , 9 ) and the head electrode ( 7 , 10 ), and
a transimpedance amplifier ( 11 , 12 ) for amplifying the signal, with an operational amplifier ( 19 , 25 ) which is operated asymmetrically by a supply voltage source ( 13 ) having a positive supply voltage,
wherein the base electrode ( 6 , 9 ) is connected to the inverting input ( 21 , 27 ) of the operational amplifier ( 19 , 25 ), and a voltage divider ( 15 ) connected to ground ( 14 ) at the supply voltage source ( 13 ) includes a partial node ( 18 ) where a partial voltage that is lower than the supply voltage is present, wherein the partial node ( 18 ) is electrically coupled to the non-inverting input ( 20 , 26 ) as well as to the head electrode ( 7 , 10 ).
2. An infrared light detector according to claim 1 , wherein the voltage divider has a plurality of partial resistors ( 16 , 17 ) which are connected in series and connected to ground ( 14 ).
3. An infrared light detector according to claim 2 , wherein the voltage divider ( 15 ) has two of the partial resistors ( 16 , 17 ) between which the partial node ( 18 ) is situated.
4. An infrared light detector according to claim 3 , wherein each of the partial resistors ( 16 , 17 ) has the same resistance value.
5. An infrared light detector according to claim 1 , wherein the transimpedance amplifier ( 11 , 12 ) has a negative feedback resistor ( 23 , 29 ) which is connected between the inverting input ( 21 , 27 ) and an output ( 22 , 28 ) of the operational amplifier ( 19 , 25 ), wherein the negative feedback resistor ( 23 , 29 ) has a value between 100 MΩ and 100 GΩ.
6. An infrared light detector according to claim 5 , wherein the transimpedance amplifier ( 11 , 12 ) has a negative feedback capacitor ( 24 , 30 ) which is connected in parallel to the negative feedback resistor ( 23 , 29 ) between the inverting input ( 21 , 27 ) and the output ( 22 , 28 ) of the operational amplifier ( 19 , 25 ), wherein the negative feedback capacitor ( 24 , 30 ) has a capacitance between 0.01 pF and 10 pF.
7. An infrared light detector according to claim 6 , wherein the capacitance is between 0.1 pF and 1 pF.
8. An infrared light detector according to claim 1 , wherein the infrared light detector ( 1 ) has at least two of the sensor chips ( 3 , 4 ), wherein one of the transimpedance amplifiers ( 11 , 12 ) is connected to each of the said sensor chips ( 3 , 4 ), and wherein the transimpedance amplifiers ( 11 , 12 ) are connected in parallel to the supply voltage source ( 13 ) and to the partial node ( 18 ).