Geiger mode APD light receiver having an active readout forming a virtual short-circuit

1. A light receiver ( 10 , 50 ) having a plurality of avalanche photo diode elements ( 10 , 12 a - c ) which are biased with a bias voltage greater than a breakthrough voltage and are thus operated in a Geiger mode in order to trigger a Geiger current upon light reception, and having a signal detection circuit ( 50 ) for reading out the avalanche photo diode elements ( 10 , 12 a - c ), wherein the signal detection circuit ( 50 ) comprises an active coupling element ( 52 ) having an input ( 54 ) connected to the avalanche photo diode elements ( 10 , 12 a - c ) and an output ( 56 ), the active coupling element ( 52 ) mapping the Geiger current at the input ( 54 ) to a measuring current corresponding to the Geiger current in its course and level, wherein the input ( 54 ) forms a virtual short-circuit for the Geiger current with respect to a potential (ground, −U BE ; U const −U BE ), and the output ( 56 ) is decoupled from the input ( 54 ).

2. The light receiver ( 10 , 50 ) according to claim 1 ,

wherein the course of the measuring current deviates from the Geiger current only for fluctuations in a higher Gigahertz range.

3. The light receiver ( 10 , 50 ) according to claim 2 ,

wherein the course of the measuring current deviates from the Geiger current only for fluctuations in a range above 2 Ghz or 3 GHz.

4. The light receiver ( 10 , 50 ) according to claim 1 ,

wherein a measurement circuit is connected to the output ( 56 ).

5. The light receiver ( 10 , 50 ) according to claim 1 ,

wherein the signal detection circuit ( 50 ) comprises a constant current source ( 58 ) connected to the coupling element ( 52 ) for setting its operating point.

6. The light receiver ( 10 , 50 ) according to claim 1 ,

wherein the signal detection circuit ( 50 ) comprises a resistor ( 60 ) connected to the coupling element ( 52 ) for setting its operating point.

7. The light receiver ( 10 , 50 ) according to claim 1 ,

wherein the coupling element ( 52 ) is configured to maintain a constant voltage at the input ( 54 ) side.

8. The light receiver ( 10 , 50 ) according to claim 1 ,

wherein the coupling element ( 52 ) comprises exactly one transistor.

9. The light receiver ( 10 , 50 ) according to claim 8 ,

wherein the transistor is operated in a common base circuit or gate circuit in that the input ( 54 ) is connected to emitter or source, the output ( 56 ) is connected to collector or drain, and base or gate is connected to a fixed potential.

10. The light receiver ( 10 , 50 ) according to claim 1 ,

wherein the avalanche photo diode elements ( 10 , 12 a - c ) comprise a first electrode ( 16 ) and a second electrode ( 18 ) used for biasing.

11. The light receiver ( 10 , 50 ) according to claim 10 ,

wherein a charging unit ( 20 a - c ) is arranged between a respective avalanche photo diode element ( 12 a ) and the first electrode ( 16 ) or the second electrode ( 18 ).

12. The light receiver ( 10 , 50 ) according to claim 10 ,

wherein the avalanche photo diode elements ( 10 , 12 a - c ) comprise a third electrode ( 24 ) as a capacitively coupled output for the Geiger current.

13. The light receiver ( 10 , 50 ) according to claim 12 ,

wherein the input ( 54 ) is connected to the third electrode ( 24 ).

14. The light receiver ( 10 , 50 ) according to claim 1 ,

wherein an additional signal channel is provided at the input ( 54 ) for capacitively feeding an additional signal into the signal detection circuit ( 50 ).

15. An optoelectronic sensor comprising at least one light detector ( 10 , 50 ) having a plurality of avalanche photo diode elements ( 10 , 12 a - c ) which are biased with a bias voltage greater than a breakthrough voltage and are thus operated in a Geiger mode in order to trigger a Geiger current upon light reception, and having a signal detection circuit ( 50 ) for reading out the avalanche photo diode elements ( 10 , 12 a - c ), wherein the signal detection circuit ( 50 ) comprises an active coupling element ( 52 ) having an input ( 54 ) connected to the avalanche photo diode elements ( 10 , 12 a - c ) and an output ( 56 ), the active coupling element ( 52 ) mapping the Geiger current at the input ( 54 ) to a measuring current corresponding to the Geiger current in its course and level, wherein the input ( 54 ) forms a virtual short-circuit for the Geiger current with respect to a potential (ground, −U BE ; U const −U BE ), and the output ( 56 ) is decoupled from the input ( 54 ), wherein the sensor is configured for at least one of distance measurement according to a light time of flight method, code reading and data transmission.

16. A readout method for avalanche photo diode elements ( 10 , 12 a - c ) which are biased with a bias voltage greater than a breakthrough voltage and are thus operated in a Geiger mode and trigger a Geiger current upon light reception, wherein the Geiger current flows through a connection between avalanche photo diode element ( 10 ) and an input ( 54 ) of an active coupling element ( 52 ) due to a virtual short-circuit with respect to a potential (ground, −U BE ; U const −U BE ), wherein, in the coupling element ( 52 ), the Geiger current is mapped to a measuring current corresponding to the Geiger current in its course and level at an output ( 56 ) of the coupling element ( 52 ), and wherein the output ( 56 ) is decoupled from the input ( 54 ) so that the Geiger current is unaffected by further processing of the measuring current.