Two-wire termination impedance generation circuit of subscriber circuit

A two-wire termination impedance generation circuit which is added to a subscriber telephone circuit including differential amplifiers outputting speech transmission signals to a four-wire speech transmission/reception circuit, and which generates a two-wire termination impedance terminating one end of a two-wire telephone line, wherein said two-wire termination impedance generation circuit of said subscriber circuit comprises:

• a network circuit for voltage/current conversion which includes a series connected capacitor and resistor and converts an output voltage from said differential amplifiers, which receives as input a line voltage of said telephone line, into an output current,
• an input point having a low impedance into which said output current flows from said network circuit after voltage/current conversion, and
• a pair of current sources which amplify said output current flowing into said input point and supply said current to said telephone line producing said line voltage, and wherein
• said resistor in said network circuit is comprised of a series connected first resistor and second resistor and a high band bypass capacitor is connected between the intermediate connecting point of said first and second resistors and ground.

A two-wire termination impedance generation circuit, which is added to a subscriber telephone circuit including differential amplifiers outputting speech transmission signals to a four-wire speech transmission/reception circuit, and which generates a two-wire termination impedance terminating one end of a two-wire telephone line, wherein said two-wire termination impedance generation circuit of said subscriber circuit comprises:

• a network circuit for voltage/current conversion which includes a series connected capacitor and resistor and converts an output voltage from said differential amplifiers, which receives as input a line voltage of said telephone line, into an output current,
• an input point having a low impedance into which said output current flows from said network circuit after voltage/current conversion, and
• a pair of current sources which amplify said output current flowing into said input point and supply the same to said telephone line, producing said line voltage, and wherein
• said two-wire termination impedance is generated by combining an internal termination impedance formed by said series connected capacitor and resistor of said network circuit and an external termination impedance directly connected between the lines of said two-wire telephone line.

A two-wire termination impedance generation circuit, which is added to a subscriber telephone circuit including differential amplifiers outputting speech transmission signals to a four-wire speech transmission/ reception circuit, and which generates a two-wire termination impedance terminating one end of a two-wire telephone line, wherein said two-wire termination impedance generation circuit of said subscriber circuit comprises:

• a network circuit for voltage/current conversion which includes a series connected capacitor and resistor and converts an output voltage from said differential amplifiers, which receives as input a line voltage of said telephone line, into an output current,
• an input point having a low impedance into which said output current flows from said network circuit after voltage/current conversion, and
• a pair of current sources which amplify said output current flowing into said input point and supply said current to said telephone line producing said line voltage and wherein
• said capacitor in said network circuit is comprised of a series connected first capacitor and second capacitor and said speech transmission signals are outputted from the intermediate connecting point of said first and second capacitors and
• said resistor in said network circuit is comprised of a series connected first resistor and second resistor and a high band bypass capacitor is connected between an intermediate connecting point of said first and second resistors and ground.