Monolithic active pixel sensor for soft X-ray imaging and advanced dosimetry

Monolithic Active Pixel Sensor

X-CHIP-04: a novel monolithic pixel detector for X-ray imaging

Technology: X-FAB XT018

Josef Gecnuk, Zdenko Janoska, Jakub Jirsa,
Lukas Tomasek, Pavel Vancura

Combining hit counting and ADC modes


X-CHIP-04 is monolithic active pixel sensor developed for soft X-ray imaging and advanced dosimetry designed in 180nm high voltage (HV) silicon on insulator (SOI) CMOS technology.


Novel feature of this sensor is capability to operate in two modes: hit counting mode (X-ray imaging) and ADC mode (advanced dosimetry). The hit counting mode is primarily designed for radiation imaging and the ADC mode is intended for measurement of energy deposited in each pixel.


Designing the monolithic active pixel sensor


X-CHIP-04 is a monolithic active pixel sensor with a 64×64 pixel matrix. Dimensions of pixels are 60μm x 60μm. The analog signals from pixels are sampled by 10-bit SAR ADCs in ADC mode or stored in 16-bit counter in Hit Counting mode. Readout digital part offers 400 MHz LVDS or 50 MHz SPI interface. The input dynamic range is from 1ke- to 10ke-. Threshold for TID effect is 2 kGy @ 15 Gy/min.

An X-ray image of a wristwatch.

Demonstrating good spectral performance


To demonstrate the spectral performance measurements with radioactive sources (55Fe and 238Pu) and X-Ray fluorescence were performed. The spectral lines and imaging capabilities can be seen in the figures.