In this work, a CMOS integrated circuit (IC) that can be employed to develop an integrated fiber optic sensor based on phase detection technique is presented. The CMOS IC combines the LED driver circuitry, optical detector and phase detector circuitry on a single chip. The designed CMOS IC provides miniaturized, portable, low cost and low power detection for quantifying analytes and for recording excited-state lifetimes ranging from nanoseconds to milliseconds.