Current-induced domain wall motion in racetrack memory promises energy-efficient analog computation using compact magnetic nanowires. This paper explores the feasibility of data converters based on current-induced domain wall motion and introduces an n-bit ADC using n racetrack magnetic nanowires. With each magnetic nanowire having a different configuration granularity, an n-bit binary or gray code is generated simultaneously. The proposed ADC structure achieves 21fJ/conversion-step at 20MHz with area under 10$μ$m2. The racetrack ADC is suitable for applications requiring dense ADC arrays, such as image sensors. This paper describes one ultra-high speed DPS imaging system benefiting from the racetrack ADC.