High-speed front end for LED-Photodiode based fluorescence lifetime measurement system

An optoelectronic front end for a high-speed solid-state based time-domain fluorescence measurement system is investigated. It consists of a source light emitting diode (LED) and photodetector (PD) pair connected to an original transimpedance amplifier. The amount of light reaching the detector from the fluorescence and the effect of different noise sources on the proposed system are evaluated. Our simulation results show that a bandwidth greater than 80MHz could be reached for PD currents with amplitudes as low as 20nA. An actual circuit was built to confirm the projected capabilities of the system.