| 摘要 |
<p>The bidirectional constant current driving circuit has an input terminal (1), an output terminal (2) and first and second power supply terminals (VP, VN), for driving a load (3) coupled to the output terminal in response to an input signal (VA) applied to the input terminal (1). The driving circuit comprises a first transistor (12) having a first electrode connected to the first power supply terminal (VP); a second transistor (11) having a first electrode connected to the first power supply terminal (VP), and second and third electrodes connected to a second electrode of the first transistor (11) ; a third transistor (14) having a first electrode connected to the second power supply terminal (VN); a fourth transistor (13) having a first electrode connected to the second power supply terminal (VN), and second and third electrodes connected to a second electrode of the third transistor (14). A first and a second resistor (15, 16) are serially connected between the third electrode of the second transistor (11) and that of the fourth transistor (13), the junction of the first and second resistors (15, 16) being connected to the input terminal (1). A coupling means couples the third electrodes of the first and third transistor (12, 14) to the output terminal (2), respectively. This circuit gives constant currents in both positive and negative directions. </p> |
