Modeling Temperature Effects on MOS Capacitors in Charge Amplifier Feedback

This article discusses the effects of temperature on an inversion-mode MOS (I-MOS) capacitor. The study extends to the transfer characteristic of a charge-sensitive amplifier (CSA) featuring dynamic signal compression by implementing this device in its feedback. This technique has been adopted to read out semiconductor detectors in experiments where both high-energy resolution and a wide input dynamic energy range are crucial, such as in free electron lasers (FELs) or astroparticle physics experiments. This study presents a theoretical analysis of the relationship between MOS capacitance and temperature with a focus on how this affects the amplifier gain. Furthermore, it discusses the methodology used to design a circuit able to mitigate some of these effects. The study has been carried out in a 180-nm commercial CMOS technology, and experimental results are reported to support the theoretical analysis.