LOGIC CIRCUITS USING POLYCRYSTALLINE SEMICONDUCTOR THIN FILM TRANSISTORS

A large scale integrated (LSI) or a very large scale integrated (VLSI) logic circuit, such as a fully programmable gate array (FPGA), comprises a plurality of polysilicon thin film transistors TFTs. The circuit, which may include a delay circuit, is asynchronous and does not comprise a clock. Thus, operations to be performed by the TFTs need not be performed within a single clock period—rather the operation of each stage of TFTs in the circuit is dependent on receiving a signal either from an input to the circuit or from a preceding stage in the circuit. Problems with variations in the threshold voltage between the TFTs are therefore avoided.