Active differential termination circuit to compensate for impedance mismatch

A differential signal driver, comprising:

• a driver circuit, including:
• a first output node coupled to a first termination node for receiving a first termination bias voltage through a first termination resistor;
• a second output node coupled to a second termination node for receiving a second termination bias voltage through a second termination resistor;
• and
• a bias network connected to the second output node and to the second termination node;
• and
• a feedback loop, including:
• a first feedback resistor connected to the first output node at a first end of the first feedback resistor;
• a second feedback resistor connected to the second output node at a first end of the second feedback resistor;
• and
• a feedback amplifier configured to provide a feedback correction current as an amplifier output signal to the first termination node,
• wherein:
• the feedback amplifier is coupled to a common node for receiving a common mode voltage as an amplifier input signal;
• the common node is connected to a second end of the first feedback resistor and a second end of the second feedback resistor;
• the second termination node is different from the first termination node;
• the second termination bias voltage is different from the first termination bias voltage;
• the bias network is separate and different from each and both of the first termination resistor and the second termination resistor;
• the bias network is connected in parallel to the second termination resistor across the second output node and the second termination node but is not connected in parallel to the first termination resistor across the first output node and the first termination node;
• and
• the feedback amplifier is configured to provide the feedback correction current as the amplifier output signal to the first termination node but not to the second termination node.

A method for providing a differential signal driver, the method comprising:

• providing a driver circuit, including:
• coupling a first output node to a first termination node for receiving a first termination bias voltage through a first termination resistor;
• coupling a second output node to a second termination node for receiving a second termination bias voltage through a second termination resistor;
• and
• connecting a bias network to the second output node and to the second termination node;
• and
• providing a feedback loop, including:
• connecting a first feedback resistor of the feedback loop to the first output node at a first end of the first feedback resistor;
• connecting a second feedback resistor of the feedback loop to the second output node at a first end of the second feedback resistor;
• and
• configuring a feedback amplifier of the feedback loop to provide a feedback correction current as an amplifier output signal to the first termination node,
• wherein:
• the feedback amplifier is coupled to a common node for receiving a common mode voltage as an amplifier input signal;
• the common node is connected to a second end of the first feedback resistor and a second end of the second feedback resistor;
• the second termination node is different from the first termination node;
• the second termination bias voltage is different from the first termination bias voltage;
• the bias network is separate and different from each and both of the first termination resistor and the second termination resistor;
• the bias network is connected in parallel to the second termination resistor across the second output node and the second termination node but is not connected in parallel to the first termination resistor across the first output node and the first termination node;
• and
• the feedback amplifier is configured to provide the feedback correction current as the amplifier output signal to the first termination node but not to the second termination node.