| 摘要 |
A transmission chip for a telephone subscriber's instrument can be used in a variety of modes, some of which involve use with other chips. Depending on which mode is in force, different amplifiers are used. Thus for plain ordinary telephone (POT) service, amplifiers 30,35 and 43 are used, for loudspeaking mode amplifiers 30, 35 and 43 are used, for handsfree use amplifiers 35, 43 and 46 are used, while for VF "dialling" amplifier 46 is used. To save power, the control block (42) detects the mode in which the set is operating and, via a control bus, operates electronic switches to disable the amplifiers not needed. |
