This article provides a review of semiconductor based ionising radiation sensors to measure accumulated dose and detect individual strikes of ionising particles. The measurement of ionising radiation (γ-ray, X-ray, high energy UV-ray and heavy ions, etc.) is essential in several critical reliability applications such as medical, aviation, space missions and high energy physics experiments considering safety and quality assurance. In the last few decades, numerous techniques based on semiconductor devices such as diodes, metal-oxide-semiconductor field-effect transistors (MOSFETs) and solid-state photomultipliers (SSPMs), etc., have been reported to estimate the absorbed dose of radiation with sensitivity varying by several orders of magnitude from μGy to MGy. In addition, the mitigation of soft errors in integrated circuits essentially requires detection of charged particle induced transients and digital bit-flips in storage elements. Depending on the particle energies, flux and the application requirements, several sensing solutions such as diodes, static random access memory (SRAM) and NAND flash, etc., are reported in the literature. This article goes through the evolution of radiation dosimeters and particle detectors implemented using semiconductor technologies and summarises the features with emphasis on their underlying principles and applications. In addition, this article performs a comparison of the different methodologies while mentioning their advantages and limitations.

This work proposes a pseudo-differential timedomain integrator using half-delay time-domain registers and adders relying on charge-based time-domain circuits. It is implemented using a 65-nm CMOS Technology and performs first order integration of time-domain information within the range of [4 ns, -4 ns] across temperature -40 o C to 80 o C. It consumes 740 µW with a supply voltage of 1.2 V at a 100 MHz clock frequency. A delay-locked-loop (DLL) based foreground calibration is used to compensate for process and temperature variations. Index Terms-Time-domain amplifier, time-domain adder, time integrator, half-delay, delay-locked-loop (DLL) clock cycles similar to first order integration in discrete-time voltage-domain signal processing.

This article presents a comprehensive assessment of the ionizing radiation induced effects on the performance of quadrature phase LC-tank based voltage-controlled-oscillators (VCOs). Two different quadrature VCOs (QVCOs) that are capable of generating frequencies in the range of 2.5 GHz to 2.9 GHz are implemented in a commercial 65 nm bulk CMOS technology to target for harsh radiation environments like space applications and high-energy physics (HEP) experiments. Each of the QVCOs consumes 13 mW power from a 1.2 V supply. The architectures are based on the popular implementation of two different types of QVCOs: parallel-coupled QVCO (PQVCO) and super-harmonic coupled QVCO (SQVCO). The various performance metrics (oscillation frequency, quadrature phase, phase noise, frequency tuning range, and power consumption) of the two different QVCOs are evaluated with respect to a Total ionizing Dose (TID) up to a level of approximately 100 Mrad (SiO2) through X-ray irradiation. During irradiation, the electrical characterization of the samples of the prototype are performed under biased condition at room temperature. Before irradiation, the QVCOs (PQVCO and SQVCO) achieve phase noise equal to −115 dBc/Hz and −119 dBc/Hz at 1 MHz offset, resulting in figure-of-merit (FoM) of −172.2 dBc/Hz and −176.4 dBc/Hz respectively. The test-setup of the TID experiment is discussed and the results obtained are statistically analyzed in this article to perform a comparative study of the performance of the two different QVCOs and evaluate the effectiveness of the radiation hardened by design techniques (RHBDs) employed in the implementations. Post-irradiation, the overall variations of the frequencies of the oscillators are less than 1% and the change in tuning range (TR) is less than 5% as observed from the tested samples.

This study presents an adaptive analogue calibration method to compensate electrode-skin impedance mismatch during biopotential signal (electrocardiogram, electroencephalogram and electromyogram) acquisition with enhanced immunity to electromagnetic interference (EMI). The method continuously measures the variation of the impedance mismatch between the electrode-skin interfaces arising primarily due to motion artefacts, and thereafter compensate for the resulting distortions at the output. The compensation is done with the help a proportional-integral-derivative controller in the feedback loop, together with the acquisition of the biopotential signals. A common mode shunt feedback at the output attenuates the common mode EMI and reduces the common mode deviation. As compared to previously reported techniques, the proposed technique refutes any need for offline manual calibration and shows a significant improvement in EMI attenuation without interrupting the main system's operation. This study explains the proposed technique with the comprising blocks, illustrates the theoretical models and analyses, and evaluates the superior performances of the proposed method by comparing the responses with those obtained from the other EMI-Immune electrode mismatch compensating front-ends existing in the literature.

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