Abstract: A telephone line circuit and system for interfacing digital exchange line circuits to a terminal interface of a switching network is disclosed. The system includes controllable active circuit impedance matching means for reducing impedance mismatch between a selected line circuit and the terminal interface. Control means controls both the active circuit impedance matching means for adjusting the effective circuit impedance to a value within a predetermined range, and the conditioning circuit gain pads for selectably adjusting the gain of a transmitted signal. Additionally, control means controls the d.c. line impedance and voltage for adjusting the effective line feed current to the subscriber loop, and provides interfaces for a plurality of line circuits to both a switching network and external processor. Supervision means provides supervision control signals to the control means and thereby permits the telephone line circuit system to provide desired telephone system functions.

Abstract: The signal generator comprises a charge transfer device providing an output signal having any desired shape so that it is particularly useful in an A/D or D/A converter. In this device charges are transferred under electrodes of which some are split in order to obtain charge portions which are then removed or transferred to the output of the device where they are added to or subtracted from previous charge portions to finally obtain a desired output signal.