| 摘要 |
<p>PURPOSE:To reduce the size of an output buffer by providing a reference voltage source, a resistor to generate a voltage corresponding to a reference current, a differential amplifier to output a voltage corresponding to the differential signal of each voltage, and a current mirror circuit to obtain an output current by utilizing a mirror effect. CONSTITUTION:When output currents required to an LED array 7 as a load are current values I1 and In, a voltage value V of a reference voltage source 11 or a resistance R of a resistor 9 is decided so that the condition of I1=In= mI0 can be established. Therefore, the channel width of P channel MOSFETs 3 and 4 can be reduced to be 1/m in respect to the channel width of a P channel MOSFET 2. Further, the chip size can be reduced corresponding to this reduction of the channel width.</p> |
