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AS5951 CT Sensor Chip

32-slice CT sensor chip with photodiodes and readout circuit

Features

  • Monolithic integration of 128-channel ADC and photodiode array in one device
  • Automatic zero offset voltage calibration across photodiode for ultra-low dark current
  • Integrated reference voltage and bias current generator for low bill of material
  • Two modes of operation: High resolution mode and low dose mode
  • Customization of pixel dimensions on request

Benefits

  • Ultra-low dark current of max. 1pA
  • Lowest input related noise of typ. 0.21fC
  • Fast integration time down to 200µs
  • Low power dissipation of max. 1mW per channel in high resolution mode
  • High ADC linearity of ±600ppm including photodiode

Product parameters

Applications Medical, Industrial and Security CT scanners
Primary Function 32-Slice CT Sensor
Channels 128
Resolution [bit] 25
Input Related Noise [fC] 0.21
Min. Power Consumption [mW per Channel] 0.82
Min. Integration Time / Line Time [µs] 200
Package Die on Foil

General Description

The AS5951 is a sensor chip for 32-slice CT detectors that combines the photodiodes and the readout circuit on a single CMOS chip. This sensor solution, which includes an array of photodiodes with ultra-low dark current and a 128-channel ADC side-by-side, allows the assembly of the pixel array on three adjacent edges of the device. Two AS5951 ICs can be placed in Z-direction enabling the design of 32-slice detectors for cost optimized CT machines.


The AS5951 has a sensor dimension in Z-direction of 15.615 mm with a pixel dimension of 0.98x0.98 mm² in high resolution mode. In low dose mode two pixels are connected together to a 0.98x1.96 mm², this mode reduces the power consumption, as only half of the ADC channels are active. Pixel dimensions can be customized on request. The sensor can be directly assembled on a substrate using a wire bonding process for manufacturing of a CT module.

Improved low dose performance can be achieved because of superior dark current of max. 1pA due to the near zero offset voltage across the photodiode. The input-related noise is very low, in high-resolution mode a typ. noise of 0.21 fC can be reached for an input current range of 200 nA.

The max. power dissipation of 128 mW per device in high resolution mode and 67.2 mW in low power mode reduces self-heating effects and lowers the overall cost of cooling the system. An internal reference voltage and bias generator reduces the bill of material. Featuring on-chip photodiodes, the AS5951 offers a cost-optimized solution for 32-slice CT detectors.

The digital data readout can be accessed via SPI interface. It is also used to configure parameters such as mode of operation, input current range, selection of reference voltage and enabling the calibration mode. An integrated temperature sensor enables monitoring of the junction temperature. 

This product suits for the following applications:

  • Medical, industrial and security CT detector modules
  • 16-slice and 32-slice CT detectors

Tools

Title Category Headline Buy
AS5951 Eval Kit Application Board Evaluation Kit for AS5951

Resources

Type Description Language
Library AS5951_Lib_v1-0-0.zip API (available via WebSocket protocol) EN
Evaluation Software AS5951_EvalSW_v0-1-15.exe GUI for the ams AS5951 Eval Kit EN

Technical Documents

Type Description Language
Special Datasheet AS5951 Short Datasheet English

Other Information

Type Description Language
Block Diagram AS5951 Block Diagram
Factsheet AS5951 Factsheet English
Image AS5951 Cross Section Image English
Image AS5951 Sensor Chip
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