Design And Circuit Simulation Of Operational Amplifier Based On Metal Oxide Thin Film Transistors

Metal Oxide Thin Film Transistor(MO TFT)is considered as a strong candidate for a new generation of electronic manufacturing devices.Its application range has extended from the initial display panel industry to the system-on-panel(SOP)design of transparent flexible circuits.The operational amplifier(OPAMP)is the core part of the analog integrated circuit.Designing an OPAMP based on metal oxide thin film transistors has a wide range of research values ??and market prospects.The main content of this paper is to study the fitting of simulation model and the design of TFT op amp.Through the analysis of experimental data,parameters suitable for circuit simulation are fitted using RPI model,and an OPAMP based on indium zinc oxide thin-film transistors(IZO TFTs)is simulated and designed.Based on the test system composed of Aligent 5100 A and probe station,the transfer characteristics,output characteristics,and C-V characteristic curves of the IZO TFTs with different aspect ratios are measured.The parameters of the thin-film transistors are extracted from the experimental data using a linear extrapolation method for fitting reference.Using the fitting tool UTMOST IV,the experimental data is fitted based on the RPI model(LEVEL 36)of SMARTSPICE,and the device parameter netlist named MODELCARD used for the simulation is extracted.The extracted MODELCARD is verified using a bootstrap inverter.Based on theoretical analysis,a single-stage amplifier composed of a two-stage positive feedback structure and a bootstrap gain enhancement structure is simulated and compared.The advantages and disadvantages of the two structures are discussed.Then the bootstrap gain enhancement structure is improved by using a cascode structure and an auxiliary amplifier.Two single-stage amplifiers with gains of 20.02 dB and 21.68 dB can be obtained respectively.The simulation results confirm that the proposed method is indeed effective.In addition,the pseudo-CMOS structure is analyzed,and a two-stage IZO TFT differential OPAMP is constructed using a pseudo-CMOS structure and a cascode inputstage.Then,the simulation is performed.The simulation results show that the gain is20.15 dB and the phase margin is 37°.Then the simulation results are compared with the simulation results of several OPAMPs proposed in literature,and the performance of the designed OPAMP is confirmed.In summary,the MODELCARD of IZO TFT used for simulation is fitted using the experimental data,and then the MODELCARD is verified using the bootstrap inverter.The design difficulties of TFT OPAMP are analyzed.The simulation performances of the two-stage positive feedback and bootstrap gain enhancement single-stage amplifier based on IZO TFTs are compared.Then,the cascode stages and auxiliary amplifiers are used to improve single-stage amplifiers.The two-stage IZO TFT differential OPAMP is constructed using pseudo-CMOS structures and cascode input stages,and the OPAMP is simulated by SMARTSPICE.Then the simulation performance is compared with other TFT OPAMPs reported in the literature in recent years.It demonstrates the good performance of the designed OPAMP.Therefore,the method used in this paper is simple and clear,which can provide the design basis for the actual manufacturing of thin film transistor OPAMPs.