This paper presents an ultrafast CMOS flash A/D converter design and performance. Although the featured A/D converter is designed in CMOS, the performance is compatible to that of GaAs technology currently available. To achieve high-speed in CMOS, the featured A/D converter utilizes the Threshold Inverter Quantization (TIQ) technique. A 6-bit Tie based flash A/D converter was designed with the 0.25 mum standard CMOS technology parameter It operates with sampling rates up to I GSPS, dissipates 66.87mW of power at 2.5 V, and occupies 0.013 mm(2) area. The proposed A/D converter is suitable for System-on-Chip (SOC) applications in wireless products and other ultra high speed applications.