1-GRad-TID Effects in 28-nm Device Study for Rad-Hard Analog Design

This paper reviews the main results of a complete electrical characterization of analog integrated circuits in 28 nm CMOS overexposed to severe radiation doses (up to 1 GRad total-ionizing (TID) dose). The proposed study is organized in two main sections. First, ON and OFF currents vs. gate-source voltage of single-finger MOS transistors (MOST) will be analyzed in both pre- and postradiation damages conditions. A particular attention will be given to the pure analog performance of standard-process (SP) MOST in terms of sub-threshold slope and consequently gm/I efficiency (i.e., transconductance over current) and it will be demonstrated as narrow and short MOST can reach—30% deviation of the efficiency at 1 Grad dose. The second part of this paper is focused on a complete design of a pixel read-out analog front-end in CMOS 28 nm for high-energy-physics (HEP) detectors. The experimental results demonstrate a slight charge-to-voltage sensitivity decreasing and a strong leakage current increasing that heavily affect the time response in both rising and falling regions of the amplifier output signal.