Temperature compensated low voltage MOSFET radiation sensor: proof of concept and a case study

Abstract

This paper presents a proof of concept performed on a new and very simple CMOS circuit configuration that implements a radiation dosimeter based on the threshold voltage difference (VTH) principle. The circuit used does not use resistors and all the transistors work in strong inversion, their mobility factor being completely canceled by the proposed architecture. Its operation exploits the relationship between radiation and VTH shifting, which allows, through a circuit configuration, to compensate for temperature variation and amplify the reaction to radiation, making it ideal for integrated industrial applications due to its simplicity and good operation. The circuit was designed for operation in areas naturally at risk of radiation, for example nuclear power plants or radiological clinics. Its advantage over other circuits that perform similar functions is mainly its low cost and simplicity of design.

Embedded Radiation sensor with OBIST structure for applications in mixed signal systems

“…Simultaneously, considering radiation variations, the absolute value of VTHN decreases while VTHP increases. This was conveniently proved in [11]. The circuit of Fig.…”

“…As said before, the sensor circuit presented here for OBIST implementation was analyzed deeply in [11]. Some of the conclusions are presented in this section in order to contribute to the global understanding.…”

“…Especially when implementing radiation sensors, analog solution is still the best way to do it [9][10]. The sensor circuit taken as CUT in this work is reported in [11]. The scheme of the embedded cell is shown in Fig.…”

“…A quick overview of the sensor cell operation is carried out here for clarity purposes. This explanation can be understood by analyzing two independent chains of transistors, n-type (T1 to T6) and p-type (T7 and T8), as explained in detail in [11]. Each branch accomplishes different uses, and consequently their designs must be taken into account independently.…”

“…The latter means that, if a given CUT presents a frequency and/or amplitude deviation of less than 5% from the nominal values (no fault injected), the circuit is passed as fault-free. This margin has previously shown to account adequately for process variation [8,11,[14][15][16] without passing faulty circuits.…”