Design Of STN-LCD Driver IC On Analog Part

With the development of the IC technologies, the mobile electronic equipments are becoming a mainstream. As the STN-LCD (Super-Twisted Nematic LCD) gives a small dimension, a weak consumption, and a low cost, it is widely used in the various mobile equipments, thus, a certain amount in the LCD market. This article describes a low cost, weak consumption driver IC, aiming at the analog part, according the characters of STN-LCD.Through out the STN-LCD driver IC design, firstly this article gives a basic frame for the whole IC with the help of the STN-LCD study, and it gives the specification according to the digital part and analog part’s analysis. Then it defines different driving voltages with their order and generating circuits according to the STN-LCD function and requirements. As the project is mainly aiming at the analog part design, this article gives a detail of the circuit design and its verification in the end so as to make sure that the design meets all the requirements.The whole analog part consists of numerous sub-blocks and it is considered2main blocks. The reference is the fundamental of the analog part. The design is optimized based on the classic bandgap reference. Under power supply voltage2.7～3.3V, the reference voltage1.32V is offered by bandgap reference. An NTAT voltage needed by LCD is generated with the help of the LDO’s function. Besides, with the help of the non-temperature-correlated voltage reference, a current reference4μA is generated for the bias circuit. All results are verified through simulation. The second main block is the Charge Pump circuit. This block gives a whole design of Charge Pump according to its voltage multiplication. According to the requirement, the Charge Pump need to give a highest power11.5V supply for the driver with this power supply voltage2.7～3.3V. Besides, this article also gives a simple presentation of the comparator and the oscillator. And the oscillator offers the frequency3MHz for Charge Pump and300KHz for the sequential part of digital. In the end, their simulation results are listed.The whole IC, using ASMC CMOS0.35um3.3V/15V process, can supply6bias voltages for STN-LCD and it is accomplished with the help of my colleagues and it meets all the requirements according to simulation results.