| 摘要 |
PURPOSE:To hold an assured current mirror ratio and at the same time to ensure the operation with the low voltage by connecting the resistance between the connections of the base of the input-side transistor Tr, the collector of the input-side transistor Tr and the base of the output-side Tr respectively and then selecting the resistance to a proper value. CONSTITUTION:Resistance R is connected between the connections of the collector of input-side transistor Tr1, the base of output-side Tr2 and the base of Tr1 respectively. In such constitution, the relation of I1 = I2 is obtained from equation (1) with the current mirror ration of ''1''. In other words, the value of R is selected so that the current of 0.9mA may be the sum of collector current i11 of Tr1, base current i1 and base current i2 of Tr2, thus obtaining the current mirror ratio of ''1''. Thus, the value of R is selected so as to satisfy equation (1) in consideration of the value of the base current of Tr1 and Tr2, accordingly holding the fixed current mirror ratio assuredly and then securing the operation. Furthermore, the driving can be secured with the low voltage since just one unit of Tr is connected at the input side. |
