austriamicrosystems (ams) is to supply a highly-integrated application-specific integrated circuit (ASIC) that enables a Siemens' photo-detector module for computer tomography (CT) to deliver higher resolution images at lower X-ray dosages. The ams ASIC, which is part of Siemensâ new Stellar CT photo-detector module, captures and digitises images of a patientâs body. It combines a high-resolution photodiode with a low-noise analogue to digital converter (ADC) in a stacked-dice (3D-integrated) configuration.
The ASIC is the result of a collaboration with Siemens that began in 2005, which was aimed at producing a new generation of photo-detector module, offering radically improved performance in line with the demand from oncologists and other medical professionals.
The ASIC has delivered a breakthrough in analogue sensor performance, reducing noise in the sensitive analogue signal chain between the photo-diode and the ADC. In order to produce such a marked improvement in performance, the ASIC development project drew on a broad range of capabilities at ams. These include:
â¢Unique ams IP, a two-stage ADC eliminates the dead-time that is required in the operation of many ADCs and therefore, is able to sample the entire input signal;
â¢sophisticated gain and offset correction, supporting the production of highly accurate outputs across a wide dynamic range of optical inputs;
â¢fine-tuning of transistor behaviour to minimise noise; and
â¢application of new fabrication techniques to enable 3D integration of a mixed-signal device.
The improvements in linearity, noise reduction and speed in the ASIC are reflected in the substantial gains in performance of the new stellar photo-detector module over the previous-generation product. According to Siemens, the new stellar detector offers:
â¢20 per cent lower noise in low-dose scans compared with conventional detectors;
â¢image resolution as fine as 0.5mm, an improvement of 0.3mm over conventional detectors;
â¢extended dynamic range, supporting the wider use of low-dose scans; and
â¢typical power consumption reduced from 1,000W to 300W, this also reduces waste heat generation, further improving signal quality and image resolution.