| 摘要 |
PURPOSE:To improve the driving characteristic of a motor by amplifying an inputted start voltage signal of a Hall element in the state without any offset and amplifying the signal to the post-stage. CONSTITUTION:A current 11 flows to a collector of a transistor(TR) Q5 in response to a voltage inputted between bases of TRs Q5, Q6 Let a base-emitter voltage of TRs Q1-Q4 be Vf, then a voltage Vf is applied between the collector and emitter of TRs Q2, Q3 respectively because the collector and the base of the TRs Q2, Q3 are connected respectively. Since the emitter-base voltage of the TR Q4 is Vf and a voltage 2Vf is applied between the collector of the TR Q3 and the emitter of the TR Q1, a voltage vf is applied between the collector and the emitter of the TR Q1 finally. Since the voltage is constant regardless of the circuit of the next stage through which a current I2 flows, the Early's effect is not caused, and the ratio of the I1 to I2 is accurately 1:1 when the emitter area ratio of the TRs Q1,Q2 is 1:1. Thus, the drive characteristic of the motor is improved. |
