Drive transistor with folded gate

摘要

A drive transistor for an ink jet print head includes a semiconductor substrate having a serpentine channel of a first type doping, the channel comprising substantially parallel first and second serpentine channel portions, the first and second serpentine channel portions defining an inner region disposed between the first and second serpentine channel portions and an outer region disposed outside the first and second serpentine channel portions. A drain of a second type doping which is disposed within the inner region. A source of a second type doping which is disposed within the outer region. The transistor has a serpentine gate that overlies the serpentine channel. An elongate drain conductor, which tapers from a wide drain conductor end to a narrow drain conductor end, at least partially overlies a portion of the drain and the serpentine channel. An elongate source conductor has two tapered source conductor portions that at least partially overly the source and the serpentine channel. The folder serpentine geometry of the channel and gate provides for a reduction in device on-resistance of about 40% compared to a conventional ink jet drive transistor.