| 摘要 |
PURPOSE:To reduce the fluctuation of an output voltage with respect to the variation of an input voltage and a threshold voltage by using a source resistor in place of a constant current source using a FET and always allowing a constant current to flow to a load resistor of the FET whose gate receives a reference voltage so as to apply an output voltage level shift. CONSTITUTION:The titled output consists of normally-on type MESFETs 100, 204, 206, a source resistor 300 and a load resistor 200. When the input voltage is a reference voltage Vref or over, a current I2 flows to the FET 204 only by the input voltage. A constant current I0 decided by the FET 100 flows to the load resistor 200 in this case and a high level output voltage is obtained. When the input voltage is the voltage Vref, the sum of the current I0 flowing to the FET 100 and the current Ic flowing to the source resistor 300 flows to the load resistor 200 and the output voltage goes to a low level. Thus, the fluctuation of the output level to the variation of the threshold value VT is less. Moreover, the high level output is decided in the output circuit independently of the current I2 flowing to the FET 204 and the effect of the input voltage is not given. |
