| 摘要 |
PURPOSE:To offer a semiconductor filter circuit reducing the dependency on a manufacture process by forming a resistive element of a filter circuit as a symmetric form of a series combined resistance between a diffusion resistive element and other resistance means respectively. CONSTITUTION:An input terminal IN is taken as an external terminal P1 in a semiconductor integrated circuit and provided with a diffusion resistor R1' for electrostatic destruction prevention, with which a polysilicon resitor R'' is connected in series to constitute one resistor R1 of the filter circuit. The other combined resistor R2 is also made up of a series circuit between a diffusion resistor R2' and the polysilicon resistor R'' in the symmetric form as the combined resistor R1. The filter characteristic Q is obtained by Equation I at K=1. In the ratio of the resistors R1/R2, the respective corresponding resistance ratios R1'/ R2' and R1''/R2'' are formed to a prescribed value not affected by the manufacture process by constituting the resistors R1, R2 with the symmetric diffusion resistors R1', R2' and polysilicon resistors R1'', R2'', and the ratio of the combined resistor ratio R1/R2 is also made nearly constant. |
