| 摘要 |
PURPOSE:To measure the temperature with a high precision, by connecting the first constant current source, the second constant current source, and a thermometric resistor and combining a resistance, which shows the same resistance value as the thermometric resistor at a prescribed temperature, with this series circuit. CONSTITUTION:In a temperature sensor 20, a constant current circuit consists of the first constant current source 21, the second constant current source 22, connecting lines 61-63, a thermometric resistor 5 (temperature coefficient alpha), and a standard resistance 4 (which shows the same resistance value as the resistor 5 at 0 deg.C). When resistance values of connecting lines 61-63 are denoted as (r) and the potential of a terminal 23 is denoted as Vx, the potential Vx is expressed by formulaI. If conditions are so set to satisfy I2=2I1, I is Vx=alphaTI1. Since currents supplied from constant current sources 21 and 22 are constant independently of temperature, the bias of a differential amplifier 9 is not changed and the gain is not changed even if the temperature of an environment where the resistor 5 is placed. As a result, a high-precision temperature measurement dependent upon only temperature and a temperature coefficient is possible. |
