| 摘要 |
PURPOSE:To improve measuring accuracy and to enlarge the degree of freedom of a circuit design of the titled circuit by connecting a sensor circuit between inverted input and output of an amplifier and connecting noninverted input of the operational amplifier with a reference voltage level. CONSTITUTION:The censor circuit Cs is connected between the inverted input and output of the operational amplifier A2. The circuit Cs has a circuit network consisting of a temperature sensor (S) and characteristic correcting resistances connected in series or in parallel and combined electric resistance for the humidity connected therewith in parallel. Then, a variation characteristic for the humidity of the combined electric resistance is approximated linearly at three-four points and the linearized resistance is provided so that a squared value of a correlation coefficiency for the approximate linearity attains the range of 0.980-1.000. Further, the noninverted input of the amplifier A2 is connected with the reference electric potential level and an AC signal is impressed on the inverted input via resistance R1. Further, since the driving voltage impressed on the sensor is equal to the output voltage and considered separately from the AC signal voltage, a stable circuit with the large degree of freedom of an AC signal generating circuit can be designed. |
