| 摘要 |
PURPOSE:To simplify the circuit, to widen the correcting range and also to attain stable operation by changing the amplification factor through the connection of plural resistors in response to a level of an input signal so as to decrease number of transistors (Trs) in use. CONSTITUTION:The amplification factor A1 when an input Vi is larger than a reference voltage Vr depends on the ratio of resistance values R1, R4 of resistors 50, 52. When the input Vi increases and an output V0 exceeds a constant voltage V1, a Tr22 is turned on, the load resistance of an amplification section 10 is a value of parallel connection of the resistor 50 and a variable resistor 70 (resistance R5) and the amplification factor A2 is a ratio of the parallel connecting value of R1, R5 to the R4, which is smaller than the A1. When the input Vi, the output V0 are increased and the current of the Tr22 is increased, a Tr23 is turned off, the load resistor of the amplification section 10 is a value of the parallel connection between the variable resistor 70 and a variable resistor 71 (resistance value R6), the amplification factor A3 is a ratio of the R1 and (R5+R6) to the R4, which is larger than the A2. |
