Offset Voltage Model Of Latch-type Sense Amplifier Based On TSMC65nm SRAM

SRAM structure is composed of the storage cell array and the peripheral circuit in which the storage unit is the core part of the SRAM array. Its structure is relatively fixed, generally determined by the technological level, so it is through improvements on the peripheral circuit that is to improve the performance of the SRAM. SRAM peripheral circuit includes:row/column address decoder (Decode), the sense Amplifier (SA, Sense Amplifier), the control circuit(Control Circuit), the buffer/drive circuit (FFIO), etc. Among those parts, the performance of sense amplifier whose function is that the weak signal of bit line can be converted to the output signal which meets the requirements.The performance of sense amplifier has a significant influence on the performance of the SRAM, thereby has greatly influence on the overall performance of the semiconductor memory, and the offset voltage is the most important performance index of the sense amplifier parameters. With the continuous improvement of microelectronics technology, if the process parameters of semiconductor devices such as the size of semiconductor devices, an on-line load capacitance and the threshold voltage do not match, the input signal might be amplified wrongly by sense amplifier amplification. So predicting the offset voltage is a key step in designing a sensitive amplifier.In this paper, we contrast and analyze the basic structure of several different types of sense amplifier and compare their advantages and disadvantages by the simulation.Finally latch-type sense amplifier is selected as the foundation of studying the offset voltage in this paper. Following the reason of circuit mismatch is analyzed, And the results the circuit mismatch may produce are analyzed. Then we put forward a new model of offset voltage.The calculation formulas of offset voltage cased by threshold voltage mismatch, transconductance mismatch and load capacitance mismatch are derived from the model according to the kirchhoff s current law. Finally we respectively compare the simulation results with the calculation results, which concluded that the model can well simulate the latch-type sensitive amplifier offset voltage.