| 摘要 |
The ringer Linear IC doubles the call signal to prevent the decreasing of ring sound pressure when many telephones are connected to one telephone line in parallel. The IC comprises a positive phase amplifying circuit (11) comprising a darlington pair (1) comprising two npn transistors; a darlington pair comprising two pnp transistors, a current source (3), and a switching transistor (Q5) for switching the darlington pairs (3), a negative phase amplifying circuit (12) having same structure to the positive phase amplifying circuit (11), and a current source (13) connected to the next stage of the negative phase amplifying circuit (2) to control the negative phase amplifying circuit (12). The output signals of the amplifying circuits (11,12) are synthesized to produce doubled output.
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