Digital-to-analog converter for multi-threshold counters that divide bits between resistor ladders and comparators

Abstract

An X-ray detector includes an N-channel digital-analogue converter controllable with K+L bits. In an embodiment, the digital-analogue converter includes a first voltage source to provide a plurality of first voltage values at tapping points; and a switch unit with N switch matrices, 2K inputs of the switch matrices being electrically conductively connected to 2K tapping points of the first voltage source. The digital-analogue converter also includes a second voltage source including N subunits. The X-ray detector further includes a discriminator unit including N comparators, at least one input of the comparators being electrically conductively connected to the associated output of the switch matrix and / or to the associated output of the subunit, so that the associated first voltage value and the associated second voltage value are associable with each comparator. A signal of an output of a pre-amplifier, and the associated first and second voltage values are comparable in the comparator.

Description

technical field [0001] The invention relates to an X-ray detector including an N-channel controllable digital-to-analog converter and a medical device. Background technique [0002] In the field of X-ray imaging (eg in computed tomography, angiography or radiography) counting direct conversion X-ray detectors may be used. X-ray radiation or photons can be converted into electrical pulses by means of suitable sensors. For example CdTe, CZT, CdZnTeSe, CdTeSe, CdMnTe, InP, TlBr2, HgI2, GaAs, or others can be used as sensor material. The electrical pulses are evaluated by an evaluation electronics system such as an integrated circuit (Application Specific Integrated Circuit, ASIC). [0003] In counting X-ray detectors, incident X-ray radiation is measured by counting electrical pulses triggered by the absorption of X-ray photons in the detector material. The size of the electrical pulse is generally proportional to the energy of the absorbed X-ray photons. By this means, spe...

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