Logarithmic conversion circuit for resistance variable sensor

Abstract

Abstract PURPOSE:To change the resistance change of the sensor in which the resistance value changes expotentially into the logarithmic value with good precision, by connecting the silicon diode in series with the resistance variable sensor and detecting the forward voltage of the silicon diode. CONSTITUTION:The silicon diode D1 is connected in series with the sensor Rtheta the resistance value of which is expotentially changed according to the physical change such as temperature change, a voltage is applied from the constant voltage power supply E1, the forward voltage of the diode D1 is input to one input terminal of the operational amplifier A1, resistor R1, transistor TR1 and resistor R2 are connected to the power supply E1, the voltage at the connection point P3 between the resistor R1 and the transistor TR1 is fed to another input terminal of the operational amplifier A1, the output of the operational amplifier is fed back to the base of the transistor TR1, temperature compensation circuit Tc is provided between the resistor R2 and ground, and the potential of the connection point P3 is taken as the output voltage.

Inventors

• 👤 Susumu Takagi

Bibliographic Details