A Study On Organic Thin-film Transistor Based RFID Tag Circuits

Organic Thin Film Transistor(OTFT)process has the advantages of flexibility,large area production,and low-process cost than the traditional silicon process.The OTFT circuits has been one of the academic research directions in recent decade.Radio Frequency Identification(RFID)technology has been used in a lot of applications in the Internet of Things(IOT),but traditional silicon-based circuits have a lot of problems such as thickness,flexibility,and the cost.So,the application of TFT in new circuits are quite attractive for the industries.And,Radio frequency identification tag based on Organic thin-film transistor is one of those topics.First of all,this thesis showed the history of thin film transistors,and compared the characteristics of a-Si TFT,poly-Si TFT,Oxide TFT and OTFT.Then,we introduced the system of RFID,and talked the application prospect of OTFT in RFID tag circuits.Secondly,we discussed several structures of thin film transistors,and demonstrated the basic OTFT preparation process.Then,in consideration of the laboratory process,we chose the top gate structure as the OTFT device structure.We measured existing OTFT devices.Then,the threshold voltage,mobility and current switching ratio are extracted and fitted to the SPICE model for circuit simulations.Secondly,we simulated the inverter based on the large threshold voltage of the depletion-mode OTFT device.Then,the basic units in the RFID tags are designed,such as logic gate,Ring oscillator,D flip-flop,counter,decoder and ROM memory.By connecting the above units,we designed a RFID tag with 195 TFT devices,and the layout of cell area is 7.3mm × 4.6mm.Finally,we tested the circuit on the chip and measured the characteristics of the newly fabricated circuits.Considering different threshold voltages between measurement data and simulation results,we modified the characterization approach and realized our target functions.