Abstract: A multimode line driver circuit is provided. The multimode line driver circuit has a first driver circuit for receiving a first differential input signal and transmitting a first differential output signal, and a second driver circuit for receiving a second driver circuit for receiving a second differential input signal and transmitting a second differential output signal. The multimode line driver circuit also has a first switch coupling the first driver circuit to a first power supply and a second switch coupling the second driver circuit to a second power supply. The multimode line driver circuit also has a transformer coupled to the output interface for transforming the first differential output and the second differential output and a mode controller configured to close the first switch in the first mode and to close the second switch in the second mode.

Abstract: A circuit comprises an amplifier circuit and a trimming circuit. The amplifier circuit includes an operational amplifier. The operational amplifier has a first input configured to receive input signals, and the operational amplifier also has a second input and an amplifier output. One of the first input or the second input is a negative input. The trimming circuit is coupled to the amplifier output. The trimming circuit includes a termination resistor coupled in parallel with at least one trimming resistor. The termination resistor is coupled to a first switch in series, and the trimming resistor is coupled to a second switch in series. The amplifier output is connected back to the negative input through the first switch.

Abstract: A line driver for a communications system requiring multiple power sources for different modes of operation comprises a current source and a voltage source coupled in parallel with the current source. The current source has a first terminal and a second terminal. The line driver further comprises a first source resistor coupled to the first terminal of the current source and a second source resistor coupled to the second terminal of the current source. The current source provides a driving current and the voltage source provides a driving voltage at the same time during operations of the communications system.

Abstract: A circuit comprises an amplifier circuit and a trimming circuit. The amplifier circuit includes an operational amplifier. The operational amplifier has a first input configured to receive input signals, and the operational amplifier also has a second input and an amplifier output. One of the first input or the second input is a negative input. The trimming circuit is coupled to the amplifier output. The trimming circuit includes a termination resistor coupled in parallel with at least one trimming resistor. The termination resistor is coupled to a first switch in series, and the trimming resistor is coupled to a second switch in series. The amplifier output is connected back to the negative input through the first switch.

Abstract: A multimode line driver circuit is provided. The multimode line driver circuit has a first driver circuit for receiving a first differential input signal and transmitting a first differential output signal, and a second driver circuit for receiving a second driver circuit for receiving a second differential input signal and transmitting a second differential output signal. The multimode line driver circuit also has a first switch coupling the first driver circuit to a first power supply and a second switch coupling the second driver circuit to a second power supply. The multimode line driver circuit also has a transformer coupled to the output interface for transforming the first differential output and the second differential output and a mode controller configured to close the first switch in the first mode and to close the second switch in the second mode.

Abstract: A line driver for a communications system requiring multiple power sources for different modes of operation comprises a current source and a voltage source coupled in parallel with the current source. The current source has a first terminal and a second terminal. The line driver further comprises a first source resistor coupled to the first terminal of the current source and a second source resistor coupled to the second terminal of the current source. The current source provides a driving current and the voltage source provides a driving voltage at the same time during operations of the communications system.