| 摘要 |
PURPOSE:To decrease parasitic capacitance and eliminate backgate effect in order to make the characteristics of a switched capacitor integrator approach to ideal ones, by a method wherein a switching transistor of the integrator is constituted on a field insulating layer, with a polycrystalline Si layer used as a channel part. CONSTITUTION:In an integrator comprising transistors 1, 2 switched by means of clock signals, a feedback capacitor CF and an operational amplifier 3, a transistor 36 with polycrystalline Si as a channel is employed for switching. The transistor 36 is formed in the process for manufacturing a capacitor 37 and an ordinary. FET37 by means of the double layer polycrystalline Si technique. In other words, a channel part 28, a source and drain 26, 27 are formed in the first layer polycrystaline Si16 on a field film by using a gate 23 of the second layer polycrystalline Si as a mask. Thereby, because the junction capacitance with the substrate is eliminated, parasitic capacitance Cp can be decreased, so that capacitance ratio CI/CF can be set accurately. In addition, because the channel part 28 is floating, backgate effect can be eliminated, so that the dynamic range can be widened. |
