The Design Of Digital Circuit And R-2R Resistance Trim Circuit In Anti-radiation DAC

With the development of aerospace technology,a large number of electronic devices are increasingly used in space radiation environment.The anti-radiation digital-to-analog converter has attracted wide attention as an important part of many electronic devices.Compared with digital integrated circuits,analog integrated circuits have poor matching due to non-ideal factors of PVT.To implement high-performance,high-precision,anti-radiation digital-to-analog converters,trimming technology is increasingly being taken seriously by designers.This paper focuses on a quad 12-bit high-voltage anti-radiation digital-to-analog converter,based on Dongbu HiTek BCD 0.18?m process.A digital and R-2R circuit is designed and simulated in Cadence ADE environment,and the same task is done under the Total dose radiation and Single event radiation environment.The trimming algorithm of R-2R resistance network is studied,modeled and verified using MATLAB.The fuse trimming circuit is designed.The main research and achievements of this paper are as follow:1.The R-2R DAC is determine to be used after analyzing the principle of different digital-to-analog converters.Considering the anti-radiation index and process,the ring-gate CMOS to be used in the digital logic circuit of this DAC,and LDMOS is chosen in R-2R circuit.2.The functions of address decoding and transmiting 12-bit data are competed in the digital logic circuit with a read-back circuit to complete the data detection.The I/O interface circuit is designed so that the data can be correctly input and read.3.LDMOS and poly resistance is used in the R-2R circuit.An analysis of the resistance matching is carried out to make a relevant matching design for the R-2R resistance.Using the basic structure,when the working voltage is±15V,DNL and INL of the circuit output are in the range of?-0.36⁰.30?LSB and?-0.64⁰.54?LSB.When the working voltage is±5V,DNL and INL are?-0.43⁰.47?LSB and?-0.80⁰.56?LSB.For the working voltage range of 0 to+5V,DNL and INL are?-0.54 to 0.55?LSB and?-0.78 to 0.89?LSB.According to the simulation results,the accuracy of the R-2R circuit designed with the segmented structure is within the requirements.Using this structure,the layout area is reduced while the output accuracy of the circuit is optimized.4.The algorithm of R-2R resistance trimming is researched and programmed in MATLAB,and verified under the different situation of adjustment bits and resistance matching level.Based on the simulation results of the Monte Carlo and the resistance trimming,it is determined that four bits(b₈^b₁₁)are trimmed.The fuse trimming technology is adopted and a fuse resistance trimming circuit is designed to detect whether the fuse is melt.5.The layout of related circuit is designed based on Dongbu HiTek BCD 0.18?m process.The output of the digital and R-2R is simulated under the Total dose radiation and Single event radiation environment.