Digital-to-time converter for fluorescence lifetime imaging

The fluorescence lifetime property of fluorophores can be used to differentiate between spectrally identical fluorophores, to reduce background signals, and to measure ion concentration in the local environment of fluorophores. Despite these advantages, use of the technique is limited because of the high cost and low throughout of existing methods for measuring fluorescence lifetime. A new type of fluorescence lifetime detector based on integrated circuit design will overcome these limitations. This abstract presents our work on one of the key building blocks of this system, a sub-nanosecond Digital-to-Time Converter (DTC), which is implemented with adjustable delay line configuration. The system utilizes two operating modes, a course mode with 510ps resolution and a fine mode with sub 50ps resolution.