| 摘要 |
PURPOSE:To constitute a pressure sensor which takes out a highly accurate output voltage in a broad temperature range, by combining two sets of series circuits of first and second capacitors whose electrostatic capacities change in correspondence with the change of pressure, a voltage generating circuit, and voltage amplitude detecting circuits. CONSTITUTION:A first capacitor 12 and a second capacitor 13, whose electrostatic capacities change in correspondence with the fluctuation of pressure are connected in series, and a series circuit 2 is constituted by two sets of the capacitors. When a voltage is inputted in the series circuit 2 and a transistor (TR) is OFF, a power source voltage is Vo. When the TR 10 is ON, the voltage is 0V. The voltage amplitude at a connecting point becomes Cp/Cr+Cp.Vo, where Cp and Cr are capacities of the first and second capacitors 12 and 13. The input voltage to a voltage amplitude detecting circuit 3 swings between 0V and Cp/Cr+Cp.Vo. A differential amplifier circuit 6 amplifies the difference in output voltages from the voltage amplitude detecting circuits 3 and 5 and outputs the result. The temperature characteristic is offset by similar circuits 2-5. In this way, a highly accurate voltage can be taken out in the broad temperature range. |
