High speed SRAM is realized such that a first dynamic circuit serves as a local sense amp for reading a memory cell through a lightly loaded local bit line, a second dynamic circuit serves as a segment sense amp for reading the local sense amp, and a tri-state inverter serves as an inverting amplifier of a global sense amp for reading the segment sense amp. When reading, a voltage difference in the local bit line is converted to a time difference for differentiating low data and high data by the sense amps for realizing fast access with dynamic operation. Furthermore, a buffered data path is used for achieving fast access and amplify transistor of the sense amps is composed of relatively long channel transistor for reducing turn-off current. Additionally, alternative circuits and memory cell structures for implementing the SRAM are described.