Re-usable 180nm CMOS dosimeter based on a floating gate device

A rad-hard monolithic dosimeter has been designed and simulated in a standard 180 nm CMOS technology. The radiation sensor (C-sensor) is based on a floating gate MOS discharge principle. The output current is processed by a current-to-voltage (I-to-V) interface and then converted by a 5-bit flash ADC. The dosimeter is re-usable (FG is recharged) and in this first version can detect a dose up to 1krad(Si) with a resolution of 30rad(Si), over process and temperature variations (0 to 85°C). The ADC allows easy further signal processing for calibration, averaging, etc. The power consumption of C-sensor plus I-to-V interface is less than 2mW from a single 5 V power supply, while the ADC consumes 160mW. The overall layout area is less than 0.25mm². The Radiation Hardened By Design (RHBD) approach guarantees that the absorbed dose does not modify the performance of the mixed-signal circuitry.