| 摘要 |
<p>A H-bridge circuit for supplying a load with a defined current comprises a first transistor for coupling a first terminal of the load to a positive potential of a power source; a second transistor for coupling the first terminal of the load to a negative potential of the power source; a third transistor for coupling a second terminal of the load to the positive potential of the power source; and a fourth transistor for coupling the second terminal of the load to the negative potential of the power source. The circuit further comprises a current sensing circuitry for sensing a current flowing through the load and for generating a voltage signal representative of the current, and a control circuit for individually controlling the operation of the first, second, third and fourth transistors by respective first, second, third and fourth control signals. The control circuit is configured for operating two transistors of the first, second, third and fourth transistors in switching mode and the remaining two transistors in linear mode. Each of the linear mode transistors has a feedback circuit associated therewith, which is operatively coupled to the control circuit and to the current sensing circuitry. Each such feedback circuit comprises a resistive element coupled between the gate/base of the associated linear mode transistor and the power source. The feedback circuits comprise a feedback transistor coupled between the gate/base of the associated linear mode transistor and the current sensing circuitry, the base/gate of the feedback transistor being connected to the control circuit for receiving the control signal for the associated linear mode transistor. The feedback transistor controls the voltage on the gate/base of the associated linear mode transistor so that a difference between the voltage signal of said current sensing circuitry and the respective control signal from said control circuit is maintained at a constant level</p> |
