John M Doty

US Patent:

6917041, Jul 12, 2005

Filed:

Mar 18, 2003

Appl. No.:

10/391061

Inventors:

John P. Doty - Bedford MA, US
Barry E. Burke - Lexington MA, US
Gregory Y. Prigozhin - Belmont MA, US

Assignee:

Massachusetts Institute of Technology - Cambridge MA

International Classification:

G01T001/24

US Classification:

25037009, 25037008

Abstract:

An event-driven X-ray CCD imager device uses a floating-gate amplifier or other non-destructive readout device to non-destructively sense a charge level in a charge packet associated with a pixel. The output of the floating-gate amplifier is used to identify each pixel that has a charge level above a predetermined threshold. If the charge level is above a predetermined threshold the charge in the triggering charge packet and in the charge packets from neighboring pixels need to be measured accurately. A charge delay register is included in the event-driven X-ray CCD imager device to enable recovery of the charge packets from neighboring pixels for accurate measurement. When a charge packet reaches the end of the charge delay register, control logic either dumps the charge packet, or steers the charge packet to a charge FIFO to preserve it if the charge packet is determined to be a packet that needs accurate measurement. A floating-diffusion amplifier or other low-noise output stage device, which converts charge level to a voltage level with high precision, provides final measurement of the charge packets. The voltage level is eventually digitized by a high linearity ADC.