Photoelectric conversion apparatus and imaging system

1. A photoelectric conversion apparatus comprising:

a diode of avalanche amplification type;

a pulse shaping circuit configured to shape an output of the diode into a pulse signal;

a pulse conversion circuit configured to convert the pulse signal having a first amplitude into a pulse signal having a second amplitude that is smaller than the first amplitude; and

a signal processing circuit configured to process the pulse signal having the second amplitude output from the pulse conversion circuit,

wherein the diode is supplied with a first power supply voltage and a second power supply voltage,

wherein the signal processing circuit is supplied with a third power supply voltage and a fourth power supply voltage, and

wherein a difference between the first power supply voltage and the second power supply voltage is greater than a difference between the third power supply voltage and the fourth power supply voltage.

2. The photoelectric conversion apparatus according to claim 1 ,

wherein the second power supply voltage is higher than the fourth power supply voltage,

wherein the fourth power supply voltage is higher than the third power supply voltage, and

wherein the third power supply voltage is higher than the first power supply voltage.

3. The photoelectric conversion apparatus according to claim 2 , wherein the first power supply voltage is a voltage on anode side of the diode, and the second power supply voltage is a voltage on cathode side of the diode.

4. The photoelectric conversion apparatus according to claim 3 , wherein the signal processing circuit is a counter circuit that counts signals output from the pulse conversion circuit.

5. The photoelectric conversion apparatus according to claim 4 ,

wherein the pulse shaping circuit is supplied with a fifth power supply voltage and a sixth power supply voltage,

wherein the pulse conversion circuit is supplied with a seventh power supply voltage and an eighth power supply voltage, and

wherein a difference between the seventh power supply voltage and the eighth power supply voltage is smaller than a difference between the fifth power supply voltage and the sixth power supply voltage.

6. The photoelectric conversion apparatus according to claim 5 , wherein the difference between the seventh power supply voltage and the eighth power supply voltage is greater than or equal to the difference between the third power supply voltage and the fourth power supply voltage.

7. The photoelectric conversion apparatus according to claim 5 , wherein the difference between the seventh power supply voltage and the eighth power supply voltage is equal to the difference between the third power supply voltage and the fourth power supply voltage.

8. The photoelectric conversion apparatus according to claim 5 , wherein the difference between the first power supply voltage and the second power supply voltage is greater than the difference between the fifth power supply voltage and the sixth power supply voltage.

9. The photoelectric conversion apparatus according to claim 7 , wherein the third power supply voltage, the fifth power supply voltage, and the seventh power supply voltage are same.

10. The photoelectric conversion apparatus according to claim 9 , wherein the second power supply voltage and the sixth power supply voltage are same.

11. The photoelectric conversion apparatus according to claim 10 , wherein the fourth power supply voltage and the eighth power supply voltage are same.

12. The photoelectric conversion apparatus according to claim 11 , wherein the pulse conversion circuit converts from the sixth power supply voltage to the eighth power supply voltage, the eighth power supply voltage being lower than the eighth power supply voltage.

13. The photoelectric conversion apparatus according to claim 1 , wherein the pulse shaping circuit is a Schmitt trigger circuit.

14. The photoelectric conversion apparatus according to claim 1 ,

wherein the diode of avalanche amplification type is provided in a first chip,

wherein the signal processing circuit is provided in a second chip, and

wherein the first chip and the second chip are layered, one on top of the other.

15. The photoelectric conversion apparatus according to claim 14 , wherein the pulse shaping circuit is provided in the first chip.

16. The photoelectric conversion apparatus according to claim 15 , wherein the pulse conversion circuit is provided in the first chip.