Consiglio Nazionale Delle Ricerche

Carl Zeiss Jena Gmbh

Politecnico Di Milano

Politecnico De Milano

Sergio Cova

Massimo Antonio Ghioni

Franco Zappa

Thomas Hartmann

Eberhard Derndinger

Robert Grub

Photodetector device comprising a semiconductor substrate () of a first type of conductivity connected to a first electrode (). Said substrate comprises an active area () made up of different semiconductor regions of a second type of conductivity () insulated from each other and connected to respective second electrodes () so that each of them can be connected separately from the others to an appropriate bias voltage. By regulating the bias voltages applied to these regions the function of optic diaphragm of the device can be controlled. The device works without needing any form of optical insulation between the different regions of the active area and always uses the same single output electrode for the signal in all the different situations of diaphragm adjustment.

Ultrasensitive photodetector with integrated pinhole for confocal microscopes

It is an integrated circuit capable of determining the quenching and the reset of an avalanche photodiode operating in Geiger mode so as to detect single photons falling on the surface of said photodiode. The circuit scheme used makes possible to reduce the size of the circuit down to a single semiconductor chip, to reduce the power dissipation and to reduce the cost of the circuit, at the same time keeping the performance at good level.

Monolithic circuit of active quenching and active reset for avalanche photodiodes

The invention concerns an output circuit for extracting the avalanche pulse produced by an avalanche photodiode for single photon detection (Single Photon Avalanche Diode, SPAD), which makes possible to detect and measure with the best possible precision the time of arrival of an incident photon on the surface of said SPAD. The circuit is built with a coupling network, connected to a terminal of said SPAD biased at high voltage and a comparator. Said network is designed so that the differentiation time constant, introduced by said block, is less than the total duration of the avalanche current pulse, but longer than the risetime of said pulse (FIG. and FIG. ). The circuit object of the invention has the virtue of being usable in all the circuit configurations for avalanche quenching in SPADs described in the technical and scientific literature.

Circuit for high precision detection of the time of arrival of photons falling on single photon avalanche diodes

The quenching circuit comprises a signal comparator (CP) having a first input connected to the photodiode (SPAD) under control and a second input connected to a balancing impedance (C) equal to that of the photodiode. At the output of the comparator (CP) there is connected a signal generator (M), which generates a quenching signal (S) having a predetermined duration each time there is an imbalance between the two inputs of the comparator (CP). Circuital switching means (I1, I2, I3, I4) are provided, capable of holding the bias voltage of the photodiode normally high and of lowering it below the breakdown level following the generation and for the entire holding time of the quenching signal.

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Milan, Italy

Sergio Cova