| 摘要 |
The battery feed circuit provides a balanced dc feed current (ITR) to a 2- wire telecommunications path. The dc current in each conductor is generated by bidirectional current sources (103, 104) each responsive to one of a complementary pair of first control signals (S1, S1) along with a second control signal (S2). The first control signals are generated by a feedback circuit (105) which monitor the differential mode voltage (VTR) across the path. To reduce power consumption, the first control signals are a nonlinear function of the differential mode voltage. Longitudinal balance is provided by the second control signal which varies the currents generated by each bidirectional current source by equal amounts. This second control signal is generated by a feedback circuit (109) which monitors the common mode voltage across the path. <IMAGE> |
