This paper presents a Resolution Adaptive Flash A/D Converter design and its performance. To achieve high speed, the proposed A/D converter utilizes Threshold Inverter Quantization technique replacing conventional analog comparators with digital comparators. The replacement results in a faster digital conversion and a reduction of the analog nodes in the ADC. The proposed ADC is a true variable resolution ADC, operates at 3-bit, 4-bit, 5-bit and 6-bit precision depending on control inputs. The proposedADC is designed with AMS 0.35µm CMOS technology and 3.3V power supply voltage and a prototype chip is fabricated. Simulation results and test results are presented.