A Power/Hardware-Efficient SiPM Readout IC Embedded in a Boost Converter for Mobile Radiation Dosimeters

Abstract

A radiation detection system provides radiation intensity to protect human life from hazardous radiation. However, the prior portable radiation detection system (mobile radiation dosimeter) structures had a problem in that various subsystems had to be designed with complex circuits. First, since the radiation detector must be driven by a relatively high voltage, a high-efficient boost converter that can receive the battery voltage and generate a high bias voltage must be implemented. Second, sophisticated sensor interface circuits that can convert the analog signal generated by the radiation detector to digital value must also be implemented. To reduce the complexity of the mobile radiation dosimeters, a power and hardware-efficient radiation detection system IC is presented for mobile radiation dosimeters. The current value of a silicon photomultiplier (SiPM) used as a radiation detector is sensed from the control information of a boost converter in the process of regulating a voltage to bias the SiPM. Due to this embedded sensing function, no additional hardware and power consumption are required for implementing and operating separate sensor interface circuits while providing sufficient radiation sensing performance. The implemented radiation detection system IC achieves 0.217-mu A(rms) input referred noise performance over 1-kHz signal bandwidth and 10-mA maximum allowable linear input current range. In addition, the proposed dc-dc boost converter can generate a high enough voltage (similar to 27 V) to drive SiPM from a lithium-ion battery with an efficiency of 72%. The irradiation test with radiation check source (Cs-137) demonstrates that the bias voltage is well regulated in the presence of high-energy radiation particles.