This paper introduces a high-speed high resolution CMOS current comparator which is used in an algorithmic Analog-to-Digital Converter (ADC) and implemented with a 0.6 μm standard CMOS process. Circuit occupies 170 x 80μm2. Proposed circuit performs comparison over a precision of 10- bit at a 100MHz clock within the 0-250 μA input current range. Power consumption is less than 500 μA.