The Study Of Read/write Circuit Modules Of Eeprom Based On Metal Oxide TFT

Metal oxide thin film transistor?MO TFT?shows enormous potential in digital circuit,such as display panel circuit and radio frequency identification devices circuit,since MO TFT has advantages of high mobility,good uniformity.The function principle and peripheral read/write circuit structure of electrically erasable programmable read-only memory?EEPROM?are stated in this thesis,according to the studies of EEPROM based on MO TFT and complementary metal oxide semiconductor?CMOS?.This thesis uses the characteristic data of MO TFT to extract model,and employs the MO TFT to simulate the EEPROM storage cell according to its program/erase characteristic,for the circuit simulation later.The inverter is a basic module of read/write circuit of EEPROM because it is able to construct other circuit.To solve the problem found in conventional N-type inverter,a circuit structure using output signal as feedback is proposed.The simulation and measurement show that the improved inverters have good static characteristic,including greater high/low noise margin and narrower transition width.A shift register,which can be used in EEPROM,is constructed by the improved inverter.The swing of output signal at 120^th implemented register is-6 V¹0 V when its pulse width is 10.6?s,thus the register can meet the requirement of function.This thesis design ring oscillator,sense amplifier and level shifter respectively:?1?The ring oscillator takes differential structure to acquire the inverted input signal as feedback for bootstrapped capacitor,and this theme can reduce the delay time per stage for improving frequency by accelerating the voltage switch time of ring oscillator.As shown in measured results,the reduction of delay time per stage on six and five stages of differential ring oscillator are both greater than 20%compared with conventional one.?2?The sense amplifier based on MO TFT is designed by learning the experience of counterpart in CMOS and optimizing the circuit according to the characteristic of MO TFT,EEPROM storage cell and Layout laws.The output voltage of measured sense amplifier is 8.73 V at simulated TFT closed,while it is 1.33 V at simulated TFT open.?3?Two different level shifters based on bootstrapped structure of multiple stages of improved inverter are proposed.The simulation result shows that the two proposed level shifters can meet basic demand of switching high voltage swing from low voltage swing.