In Situ Measurement of TID-Induced Leakage Using On-Chip Frequency Modulation

An on-chip measurement circuit that was specifically designed to capture the high-speed transient characteristics of photocurrent is employed to measure total-ionizing-dose (TID)-induced leakage from 10 keV X-rays. This circuit uses a photocurrent-controlled oscillator (PCO) to produce an analog frequency, which provides linearity comparable to traditional, off-chip methods of TID measurement. The circuit was fabricated in a sub-50 nm, fully depleted silicon-on-insulator (FD-SOI) technology. TID-induced leakage currents were measured using the circuit and results were compared to off-chip direct measurements from identical transistor arrays. Additionally, potential in situ applications of this circuit in conjunction with a TID-compensating back-gate biasing technique are explored.