发明名称 |
Subscriber line interface circuit with complex impedance |
摘要 |
For the purpose of realizing a line circuit, especially a two-wire four-wire conversion circuit of a telephone exchange in the form of LSI and providing the conversion circuit with an impedance which is suitable to a side tone characteristic of the telephone set, in a line circuit composed of a hybrid circuit wherein the four-wire input line is connected to the two-wire subscriber line via a buffer amplifier and a terminating impedance and in addition the four-wire output line is connected to the output of a subtractor which subtracts an input signal of the four-wire input line passed through a filter circuit from a signal fed from the two-wire subscriber line, the terminating impedance is formed by a resistor component and in addition a feedback circuit having such a transfer characteristic that the impedance of the line circuit seen from the two-wire subscriber line side will become a specified complex impedance is installed between a line which couples the two-wire subscriber line to the subtractor and an input of the buffer amplifier.
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申请公布号 |
US4558185(A) |
申请公布日期 |
1985.12.10 |
申请号 |
US19820445976 |
申请日期 |
1982.12.01 |
申请人 |
NIPPON TELEGRAPH & TELEPHONE PUBLIC CORP.;HITACHI, LTD. |
发明人 |
MORIKAWA, YUICHI;SAITO, KAZUO;AMADA, EIICHI;SHIRASU, HIROTOSHI |
分类号 |
H04B3/03;H04B1/58;H04M1/58;H04Q3/42;(IPC1-7):H04B1/58 |
主分类号 |
H04B3/03 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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