Research On Offset Compensation Technology For Sense Amplifier

As an important part of the integrated circuit industry,DRAM is deeply loved by the majority of users because of its unique advantages of high density and low cost.However,with the popularity of DRAM industry,people no longer only meet the needs of high density and low cost.Process size reduction has become the development trend of DRAM.But with the continuous reduction of process size,the effect of process fluctuation on transistor threshold voltage becomes more and more serious.As an important part of the core array,the offset voltage caused by the mismatch of transistor threshold voltage of sense amplifier(SA)will seriously affect the accuracy of DRAM data reading.In order to deal with such problems,this paper first introduces the composition structure,common command operations and core timing of DRAM.I have some basic knowledge of DRAM as a whole.Then,the reasons for the reading failure of the sense amplifier are analyzed through the SA butterfly diagram,and then three offset elimination structures are introduced.These structures are analyzed in detail from the timing,working process and simulation results,from which some inspiration for offset compensation technology is obtained.Finally,two kinds of offset compensation sense amplifiers are proposed based on the flip point optimization technique,trip point compensation sense amplifier(TPCSA)and high offset compensation sense amplifier(HOCSA).TPCSA improves the sensing margin by amplifying the reference bit line voltage in the process of charge sharing.HOCSA compensates the offset voltage by changing the driving ability of PMOS transistor and expanding the voltage difference between the bit lines at both ends.TPCSA and HOCSA have good temperature stability on the basis of maintaining low offset voltage.Under the condition of 1.05 V power supply,the sense yield of TPCSA is increased by 80%,30% and 12.3% respectively compared with OCSA,BRV-SA and OMCSA.HOCSA is increased by 71.6%,23.6% and 6.8%respectively.In terms of power consumption,TPCSA and HOCSA also have obvious advantages over OCSA.In addition,compared with OCSA and OMCSA,TPCSA reduces the offset voltage by 62.7% and 30.8% respectively,while HOCSA reduces the offset voltage by90%,73.7% and 81.5% respectively compared with OCSA,BRV-SA and OMCSA.Therefore,the proposed TPCSA and HOCSA can overcome the offset problem caused by transistor mismatch.