초록 ▼

An active quench circuit for interrupting the current flow in an avalanche photodiode (APD) operating in Geiger mode and for resetting the APD. The invention increases the speed of quenching and reduces the time required to bring the APD voltage back to its operating voltage above the breakdown volt

An active quench circuit for interrupting the current flow in an avalanche photodiode (APD) operating in Geiger mode and for resetting the APD. The invention increases the speed of quenching and reduces the time required to bring the APD voltage back to its operating voltage above the breakdown voltage. The circuit includes a small inductor which isolates the reset circuit from the APD during the initial discharge and which provides a current pulse into the APD immediately after the end of the quenching operation to recharge the diode. The reset circuit also includes a diode assembly that increases the speed of the avalanche current pulse and that prevents the circuit from oscillating or latching under certain operating conditions. The circuit presents a low impedance to the APD during during reset, and is much less sensitive to the APD capacitance than prior art circuits.

대표청구항 ▼

A circuit for operating an avalanche photodiode (APD) in Geiger mode, including: bias means for applying a first voltage to a first terminal of the APD, the first voltage being less than the breakdown voltage of the APD with respect to a reference voltage and having a polarity to reverse bias the AP

A circuit for operating an avalanche photodiode (APD) in Geiger mode, including: bias means for applying a first voltage to a first terminal of the APD, the first voltage being less than the breakdown voltage of the APD with respect to a reference voltage and having a polarity to reverse bias the APD; reset means for applying a second voltage to a second terminal of the APD during a first phase of operation, the second voltage being such that the APD is reverse biased above its breakdown voltage when the second voltage is applied to the APD second terminal, the reset means presenting a first impedance to the second terminal of the APD; means, responsive to a quench signal, for connecting a second impedance between the APD second terminal and the reference voltage during a second phase of operation, the second impedance being less than the first impedance, and for disconnecting the second impedance from the second terminal in the absence of the quench signal; and means for detecting an increase in the current flowing through the APD and for producing the quench signal in response thereto to initiate the second phase of operation, the detecting means being further operative for removing the quench signal after a predetermined delay to terminate the second phase of operation; and wherein the reset means further includes an inductance having a fixed value connected in series between the second voltage and the second terminal of the APD for injecting a current pulse into the APD second terminal immediately following the end of the second phase.