A CMOS flash analog-to-digital converter (ADC) designed for high speed and low voltage is presented. Using the Threshold Inverter Quantization (TIQ) comparator technique, a flash ADC can be applied to low supply voltage. A fat tree encoder that has signal delay of O(log2N) is used for performance. A 6-bit and an 8-bit flash ADC were designed with 0.07 µm CMOS technology and 0.7 V power supply voltage. The 6-bit ADC operates up to 4.76 giga samples