Radiation dosimeter IC uses floating gate

Radiation dosimeter IC uses floating gate

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Integrated Circuits Malaga SL (Mallorca, Spain) has developed radiation dosimeters based on floating-gate technology to overcome certain drawbacks of more conventional radiation-sensitive field effect transistors (RadFETs).
By Peter Clarke


The sensitivity of the floating gate dosimeter is 100 to 500 times better than RadFET technology, IC-Malaga claims.

Radiation measurements are necessary in applications such as nuclear safety, medical and aerospace engineering. However, RadFET dosimeters demand the use of specific manufacturing technologies for their fabrication, making it difficult to integrate the monitoring system monolithically in a conventional CMOS IC.

Comparison of RadFET and floating-gate IC dosimetry characteristics (*depending on RadFET). Source: IC-Malaga.

The floating-gate approach is based on the discharge of a floating capacitor connected to the gate of a MOS transistor. The result is an output signal whose frequency is proportional to the variation of the charge stored in the floating gate due to radiation.

IC-Malaga radiation dosimeter ICs offer a high sensitivity approach to the measurement of ionizing radiation (gamma and proton) in single chip.

Floating-gate sensors can be manufactured in standard CMOS processes, which allows the integration of the sensing unit together with additional circuits in the same IC. The additional circuits include a charging circuit for the floating capacitor, circuits for radiation sensor monitoring and signal processing, together with a serial communication block. As a result, radiation measurements are available in digital format.

Next: Other benefits

Dosimeters with floating gate technology offer superior linearity across their measurement range and sensitivity down to 0.1 milligray while being able to withstand up to 250 gray total ionizing dose. The combination of high sensitivity with large radiation range is achieved thanks to an internal automatic gloating gate recharging process. Once the floating gate is discharged, the sensor is recharged automatically (every 0.6 Gray).

In addition floating-gate dosimeters do not require an external power supply during irradiation and can work in a passive mode. IC-Malaga dosimeters are available in QFN32 5mm by 5mm package. An extra dosimeter is included as a redundant unit in the same package for used in extra safety applications.

The dosimeters have been successfully tested in space environment applications, taking part in the 4M lunar flyby mission from Luxspace. There, the radiation level during the whole mission was monitored and transmitted by the dosimeters. At present IC-Malaga floating-agte dosimeters are being validated for high energy physics measurement applications at the Large Hadron Collider accelerator complex, at CERN facilities.

IC-Malaga, founded in 2002, specializes in analog circuit design and industrial applications. IC Malaga is sister company to IC-Haus GmbH (Bodenheim, Germany) and works with IC-Haus on chip fabrication while also serving as a distributor for IC-Haus products in Spain and Portugal.

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