| 摘要 |
PROBLEM TO BE SOLVED: To provide a constant current power source with which accuracy is improved even in the case of an inexpensive resistor having a large temperature coefficient. SOLUTION: The current of a constant current power source flows to a current detection resistor 5. The voltage at both the terminals of the current detection resistor 5 is impressed through a current detection buffer amplifier 6 to one end of a correction resistor 9. The other end of the correction resistor 9 is connected to the minus side input terminal of an operational amplifier 11. Between the input terminal and output terminal of the operational amplifier 11, a feedback resistor 10 is connected. The correction resistor 9 has the temperature characteristics (temperature coefficient) practically equal with the current detection resistor 5 and is arranged so that the temperature conditions can be practically equal with the current detection resistor 5. Based on the output voltage of operational amplifier 11, the current value of constant current power source is made coincident with a prescribed value. |
