US Patent 7577016 Twin-cell semiconductor memory devices

Twin cell type semiconductor memory devices are provided that include a plurality of main bit lines and a plurality of reference bit lines. Each of the reference bit lines correspond to respective ones of the main bit lines to form a plurality of bit line pairs. A plurality of sense amplifiers are provided that are electrically connected to a respective one of the plurality of bit line pairs. At least one of the plurality of main bit lines or the plurality of reference bit lines is interposed between the main bit line and the corresponding reference bit line of each bit line pair. At least some of the main bit lines may cross respective ones of the reference bit lines in a sense amplifier region of the semiconductor memory device that contains the plurality of sense amplifiers.