| 摘要 |
PURPOSE:To control the temperature coefficient of the output current of a reference current source and to reduce the chip occupancy area, by adding a simple external circuit consisting of a variable resistor. CONSTITUTION:The collector resistances of transistors (TR) Q1 and Q2 are divided into resistances R3a/R3b and R4a/R4b respectively. A series circuit of resistances R4c, (Rx+Ry) and R3c is connected to the joint between the resistances R3a/R3b and R4a/R4b. In this case, the resistance (Rx+Ry) serves as a single variable resistor and is attached externally to a semiconductor integrated circuit. Then the resistance (Rx+Ry) is controlled to set the collector currents of the TRs Q1 and Q2 at proper levels. Thus the temperature coefficient of the output current of a reference current source is minimized. Thus the occupancy area of the reference current source can be reduced within a chip since the temperature coefficiency of the output current is controlled by an external variable resistance.
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