Integrated sensor chip cuts cost in CT scanners

By Gina Roos, editor-in-chief

The new AS5950  integrated sensor chip for X-ray detection from ams is designed to reduce the cost of computed tomography (CT) scanners. Claiming an improved CT detector for more detailed imaging at a lower system cost, the AS5950 combines a high-sensitivity photodiode array and a 64-channel analog-to-digital converter on the same die. This makes the AS5950 easier to mount in a CT detector module.

“Current CT scanner manufacturers need to assemble a discrete photodiode array on a complex PCB, connected via long traces to a discrete read-out chip,” said ams. “In 8- and 16-slice CT scanners, replacement of this complex PCB assembly with a single AS5950 chip dramatically reduces the image-noise performance and — importantly — manufacturers’ materials and production costs.”

The AS5950 comes with a pixel size of 0.98 × 0.98 mm². This can be customized to meet an OEM’s specific needs within a “reasonably short lead time,” said ams. The sensor can be directly assembled on a substrate using a wire-bonding process for manufacturing of a CT module.

Key specifications include:

• Ultra-low input related noise down to typ. 0.20 fC
• Fast integration time down to 200 µs
• Low power dissipation down to typ. 0.65 mW per channel
• High ADC linearity of ±300 ppm of reading and total linearity of ±600 ppm including the photodiode
• Up to 25-bit resolution
• The total sensor dimension in the Z-direction can be selected between 16 mm or 32 mm thanks to the three-side buttable design.
• Operates in high-resolution mode with a standard pixel size of 0.98 × 0.98 mm² or in large Z-coverage mode connecting two pixels for a total size of 1.96 x 0.98 mm² .

The AS5950 sensor IC as well as the AS5950M reference module, developed with partners, are available for sampling now. An evaluation kit and a module reference design are also available. It comes with an FPGA board and software to demonstrate all relevant performance parameters.