| 摘要 |
PURPOSE:To improve the driving characteristic of a motor by outputting a current in response to a voltage of a Hall element detection signal inputted to a differential amplifier circuit from the collector of a 3rd transistor(TR). CONSTITUTION:A current I1 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-Q3 be Vf, then a voltage Vf is applied between the collector and emitter of TRs Q2 because the collector and the base of the TR Q2 are connected respectively. Since the emitter-base voltage of the TR Q3 is Vf and the base of the TR Q3 is connected to the collector of the TR Q1, a voltage 2Vf is applied to the TR Q1. Since the voltage is nearly constant (Vf and 2Vf) regardless of the circuit of the next stage through which a current 12 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. |
