COMPACT ACTIVE QUENCHING-CIRCUIT FOR FAST PHOTON-COUNTING WITH AVALANCHE PHOTODIODES

A compact and flexible circuit for operating avalanche photodiodes in Geiger mode was designed, fabricated, and tested. A new voltage driver stage, based on fast n-channel double-diffused metal-oxide-semiconduc tor (DMOS) transistors in a bootstrap configuration, makes it possible to obtain quenching pulses up to 25 V amplitude and fast active reset of the detector. At 20 V excess bias voltage above the photodiode bre akdown level, an overall deadtime shorter than 36 ns is attained. The avalanche pulse charge is minimized by means of a mixed passive-active quenching approach, thus reducing self-heating and afterpulsing effec ts in the photodiode. A user-controllable hold-off time is available f or further reducing the afterpulsing effect. The saturated counting ra te of the circuit exceeds 25 Mcounts/s, but, by working with avalanche photodiodes with high breakdown voltage (250-400 V) and high avalanch e current (10-40 mA), a practical limit is set at about 9 Mcounts/s by thermal effects in the detector. Gated-detector operation with gate t imes down to 10 ns is provided. The suitability of the new active-quen ching circuit for the development of compact, all-solid-state instrume nts for high-performance photon counting was verified in experimental tests. (C) 1996 American Institute of Physics.