Abstract: A readout circuit (29) for reading active pixels in a sensor (10) having at least one sensor segment (11) each containing addressable pixels (12) includes a respective sample and hold unit (28) for sampling and holding an analog value associated with a corresponding pixel, and an analog multiplexer (35) in each segment having an addressable channel coupled to each sample and hold unit for carrying the corresponding held value of the respective pixel. A lookup table (38) stores addresses of predefined neighboring pixels associated with the respective pixel. An encoder (36) is responsive to one or more trigger signals for generating an address in the lookup table, and a controller (37) feeds the address to the lookup table and successively feeds the addresses of the predefined neighboring pixels output by the lookup table to the analog multiplexer.

Abstract: A method and threshold discrimination circuit for threshold discriminating an accumulated charge signal in a charge readout sensor, wherein the accumulated charge signal is shaped with a filter prior to effecting threshold discrimination thereof, and a slew rate of the filter is limited so that the filtered accumulated charge signal reaches a predetermined threshold at a time that remains constant irrespective both of an amplitude of the signal and of charge collection time. Such a threshold discrimination circuit finds particular application in a charge readout sensor in a nuclear imaging system where very accurate determination of the time of photon emission is required.

Abstract: A method for detecting an active pixel in a sensor having a plurality of addressable pixels, comprising detecting a trigger event that causes a pixel to go active and setting a corresponding resettable latch from an initial unset logic state to a set logic state and establishing a time window during which another pixel which becomes active is assumed to originate from the same trigger event. For all pixels that become active within the time window a corresponding analog value of the pixel is sampled and held in response to a logic signal indicative of another pixel currently being active, and an incident time of the pixel going active is established. Each of the latches in the segment is sparsely read so as successively to identify latches which are in the set logic state each corresponding to an active pixel having a known address in the sensor segment. The known address of each active pixel is associated with the incident time of the pixel going active and the respective sampled and held analog value.

Abstract: A method and threshold discrimination circuit for threshold discriminating an accumulated charge signal in a charge readout sensor, wherein the accumulated charge signal is shaped with a filter prior to effecting threshold discrimination thereof, and a slew rate of the filter is limited so that the filtered accumulated charge signal reaches a predetermined threshold at a time that remains constant irrespective both of an amplitude of the signal and of charge collection time. Such a threshold discrimination circuit finds particular application in a charge readout sensor in a nuclear imaging system where very accurate determination of the time of photon emission is required.