Akademik Veri Yönetim Sistemi
24th IEEE International Conference on Electronics, Circuits and Systems (ICECS), Batumi, Gürcistan, 5 - 08 Aralık 2017, ss.165-169
Current input, voltage output analog integrators are important electronic components for photo-current measurement applications such as diffuse light tomography and spectroscopy applications. In this work, current input, analog voltage output integrator has been designed and simulations have been tested for biomedical imaging purpose. Researchers want to know photon accumulations in different phantom layers for photon measurement applications, especially for diffuse optical tomography (DOT) devices. In continuous wave (CW) DOT (CWDOT) measurements, there is no way to guess photon trajectories except running Monte Carlo (MC) simulations on computer. In time resolved (TR) biomedical optic imaging systems there are some ways to guess photon trajectories, but this modality is requiring very expensive laboratory situations such as dark room, optical table, photo-multiplier tubes (PMT), scientific camera systems, etc. In this work, one analog integrator circuit has been designed to use for CWDOT systems in the future. Electronic current measurement sensor will be one pn type semiconductor photo-detector. Photo-detector current is modelled by current-source in simulations. The circuit is one integrator at top. Integrator has one operational amplifier, integrating capacitance, and switching n-channel and p-channel metal-oxide silicon (MOS) field-effect transistors (MOSFET). The purpose of this work is to accomplish to acquire different depth layer photons by the pn-type photo-detector from tissue or tissue phantom. To acquire different depth layer photons, time difference circuit should be designed. Time differences between different acquisitions are important parameter to guess penetration depth of photon accumulations. Time difference will be done by drawing layout of time delay circuit, but not in this work. One micrometer conducting length difference is generating approximately five femtoseconds time delay in average CMOS technology for polysilisium and metal wires. One n-channel MOSFET transistor switch and one low-voltage threshold inverse connected depletion mode p-channel MOSFET transistor are connected cascade to photodetector for time delay purpose. Integrating pulse signals are triggering switching transistors over delay line wires.