摘要 |
As for a "system on panel" in which a control circuit and a driver circuit as well as a display device are integrally formed over a substrate such as a glass substrate, more sophistication is expected by fabricating an input unit over the same substrate. Input of a semiconductor device is generally performed by pushing or touching a button like input unit with fingers or the like. In that case, glass is often used for a counter substrate; however, it is difficult to form a button from glass and to provide it directly on the substrate due to the nature of the material. It is an object of the present invention to provide a semiconductor device at a lower price, in which the input operation can be performed without employing an external input unit. A variable capacitor is formed from a pair of electrodes and a dielectric interposed between the electrodes over a substrate, and an external input is detected by changing capacitance of the variable capacitor by a physical or electrical force. Specifically, a variable capacitor and a sense amplifier are provided over the same substrate, and the sense amplifier reads the change of capacitance of the variable capacitor and transmits a signal in accordance with the input to a control circuit.
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