Design12Bit Video DAC Based On Matlab And Hspice Software

With the fast development of signal processe and integrated circuit manufacturingtechnology today, modern signal’s storage, processing and transmission are using moreand more digital circuit, but the real world is still an analog world, so as the interfacecircuit between the analog world and the digital world, converters is very necessary.Analog video interface include CVBS, VGA, YUV, etc., these interfaces canconvert the on chip digital signal to analog signal for output. With the video refresh rate,and increasingly high resolution, the digital-to-analog converter’s conversion becomemore and more high speed, and its resolution become more and more precision.The process technology used in this thesis design is TSMC0.11um1P6M. Thepower supply of this process is1.2V and3.3V,1.2V for low voltage digital device and3.3V for high voltage analog and IO device. The thesis first introduces several types ofnormal used digital-to-analog converters and selects current steering structure for ourvideo DAC design. For Current steering DAC, this thesis introduces the basic blockdesign of current unit, also discuss and optimize the current unit matrix on/off sequencefor improving the DC precision of DAC, meanwhile introduce the normal method ofminimizing voltage glitch.When the DAC has device mismatch, harmonics will exist in its output spectrum.Random thermometer code method can effective remove the harmonic and change it towhite noise. Based on MATLAB software, this thesis separately model ideal andnon-ideal DAC and add Random thermometer code method to DAC, the behaviormethod show a right function result.Based on the HSPICE software simulation environment, this thesis completedeach block circuit of the DAC design and simulation, then random thermometer codemethod is added to the current steering DAC. The top level simulation shows that whencurrent unit matrix mismatches each other, the output spectrum will contain harmonictones. When enable the random thermometer code method, the output spectrum only haswhite noise floor without harmonic tones. And the simulation result meets theMATLAB behavior modeling. This thesis from easy to hard, basic to system, analysis and introduce the currentsteering DAC. To the application of reducing current steering DAC harmonics, thisthesis has very good reference value.