Design Of 12 Bits 1GS/s Current-steering DAC

Digital to analog converter is a kind of chip which transforms digital signal into analog signal.It plays the role of bridge between digital domain and analog domain,and its importance is self-evident.In recent years,with the rapid development of 5G communication,4K ultra clear video screen,ultra-high speed real-time monitoring,radar and other fields,People's demand for DAC is higher and higher,which is mainly reflected in two aspects: high speed and high precision.Of course,there are certain requirements for power consumption.Among many types of DAC,current steering DAC has the inherent characteristics of high speed and high precision.It is necessary to design an excellent current steering DAC in this application background and demand.First of all,this paper introduces the research results of current steering DAC at home and abroad,lists the products that can represent the latest achievements in the industry,introduces the application background and occasions of high-speed and high-precision current steering DAC,points out the importance of studying high-speed and high-precision current steering DAC,and then introduces the principles of three kinds of common digital analog converters,namely,charge scaling DAC,voltage scaling DAC,current scaling DAC And analyzed their advantages and disadvantages,Next,the paper focuses on the analysis and research of the non ideal factors that affect the performance of current steering DAC,including current source matching,switch synchronization,segmentation strategy,limited output impedance of current source,etc.;through the analysis of the non ideal factors that affect the performance of current steering DAC,this paper finally adopts the segmentation strategy of 5+3+4,that is,the high 5 bits and the middle 3 bits are encoded by thermometer,and the low 4 bits are encoded by binary The current steering DAC designed in this paper mainly includes band gap reference voltage module,register module,binary thermometer code circuit,limiting circuit,current source array switch.Finally,through the analysis of current source layout,the whole circuit layout isdrawn.Based on the SMIC 0.18 um standard CMOS 1p6 m process,in this paper,a 12 bit,1GHz high-speed and high-precision current steering DAC is designed on cadence EDA platform.The main structure adopts the 5+3+4 segmentation strategy,in which the analog part adopts 3.3V voltage power supply,the digital part adopts 1.8V power supply,the full range current is 20 m A,the load is 25?,under the input signal of1.708984375 MHz,48.583984375 MHz,243.408203125 MHz,487.548828125 MHz and the clock signal of 1GHz,the SFDR measured is 93.5d B,84.3d B,75.02 d B,75.1d B,the INL are less than 0.25 LSB and DNL are less than 0.025LSB;and the overall power consumption is 86.58 mw.