Polycrystalline Silicon TFTs Threshold Voltage Compensated Bias Current Generator for Analog Circuit Design

摘要

A new bias current generator (BCG) with threshold voltage compensation for analog circuit design implemented with low-temperature polycrystalline silicon thin-film transistors (LT poly-Si TFTs) is proposed. The proposed topology can be used in AMOLED display applications or in other poly-Si TFTs current mode analog circuits. The functionality of the proposed circuit has been verified through simulations with HSpice. In order to obtain realistic simulations, parameters extraction in fabricated LT poly-Si TFTs was made. The simulation results indicate that the output current is independent from the transistors threshold voltage, without requiring additional capacitors or control signals for the threshold voltage compensation. Furthermore, low supply voltage is needed (10 V) and the impact of the threshold voltage variations was reduced from 54% to 3% for an output current of 2.5 μA.