| 摘要 |
PURPOSE: To obtain a reference current, changed linearly in respect to an input current having possibility to be changed up to a supply voltage rail value by providing a voltage dividing network and a linear reference current generating circuit. CONSTITUTION: A field effect transistor(FET) 4 has a source connected to a supply voltage terminal 3, gate connected to an enable terminal 5, and drain connected through a resistor 6 to a voltage reference node 8. A voltage divider for adding a reference voltage to the voltage reference node 8 is composed of the FET 4 and resistors 6 and 7, and the level of this reference voltage is determined by a convert voltage at the supply voltage terminal 3 and a ratio between the resistance values of the resistors 6 and 7. The linear reference current generating circuit is composed of a cascade current mirror 11 and a current mirror 12 or the like. Thus, the level of the reference current changes, with respect to the input voltage, to be changed up to the value of a supply voltage rail. |
