| 摘要 |
PURPOSE:To stabilize a driving current by determining the ratio of the currents flowing at the current output side output transistor(Tr) and the current input side output Tr of the Tr output circuit according to the mirror ratio of current mirror circuits of PNP type and NPN type Trs. CONSTITUTION:An output circuit is composed of a current output side output transistor TrQ1 and a current input side output TrQ2. A first current mirror is composed of PNP type Q3-Q5, the circuit of front stage is connected to the collector of the Q3, and the collector of the Q4 is connected to the base of the Q1. A second current mirror is composed of NPN type TrQ6-Q8, the circuit of the front stage is connected to the collector of the Q6, and the emitter of the Q7 is connected to the base of the Q2. When the area ratio of the emitters of the Q3, Q4 is set to 1:n, the area ratio of the emitters of the Q6, Q7 is set to 1:m, the Ic of the Q3, Q6 are I1, I2 and the Ie of the Q1, Q2 are I01, I02, I02:I02=n XI1:(1+m)XI2 is satisfied. Thus, the influence of the variability of the Trs is removed to stabilize a driving current. |
