Abstract: A driving current control circuit capable of controlling the logarithmic base current of two transistors in a current driver to control a drive current for a motor. This control circuit controls the current of the current regulator depending on a control signal, thereby controlling the driving current for the transistors in the current driver. The control circuit includes an output current mirror composed of two output-side transistors and a single input-side transistor. The two output-side transistors control the inflow and outflow of the driving current for the current driver. A single phase compensating condenser is connected to the input-side transistor. This arrangement makes the entire circuit simple and compact and causes an improved controlling characteristic.

Abstract: A motor controlling circuit used for controlling the drive of a motor, and particularly to improvements of the control characteristics of the amplifier. A current setting transistor for setting an amount of current flowing from a differential amplifier to a predetermined value is disposed on the downstream side of the differential amplifier. The amount of current flowing across this current setting transistor is varied in response to the level of an input signal to the amplifier, so that the current outputting capability of the differential amplifier is proportional to the level of the input signal. Accordingly, when the level of the input signal is small, the gain of the amplifier is made small, and a gain for an amount of ripple at that time is also made small. Hence, it is possible to control an adverse effect of the ripple carried on the input signal when the level of the input signal is small.