Design of a high dynamic range integrated charge to digital converter for online dosimetry in radiotherapy
Résumé
The Intensity Modulated Radiotherapy allows a more efficient dose delivery in the tumour leading to a reduction of the dose deposited in the nearby healthy organs. However, this technique requires additional resources to perform on line dosimetry and insure patient safety. A Charge to Digital Converter has been designed in a CMOS 0.35 µm process to read-out a 2D dedicated gaseous detector designed at LPSC. The Charge Balancing Integration technique coupled to an internal 6- bit Analog to Digital Converter allows high resolution and high dynamic range to be reached. This 16-channel, 16-bit converter exhibits a 6 fC LSB value, a nonlinearity better than 0.1 LSB and a RMS noise lower than 0.5 LSB.