Some analog building blocks for TFT circuits

The analog circuits fabricated by the amorphous and/or polycrystalline silicon TFT suffer from very wide deviation effects of the threshold voltage Vth and the current gain /spl beta/. This paper proposes some analog building blocks for TFT circuits, in which the techniques to reduce the effects caused by the threshold voltage and the current gain /spl beta/ mismatch of the transistors are used. First, Vth and /spl beta/ deviation-free differential amplifier is discussed. Second, Vth deviation-free current source is proposed. Finally, Vth and /spl beta/ deviation-free class A amplifier is presented. The test chip to verify the proposed idea has been simulated and designed using VDEC design environment.