Circuit, apparatus and method for an adaptive voltage swing limiter

12) A differential amplifier circuit having a voltage source and a current source coupled to a node, comprising:

• a first electrical path coupled to the voltage source and the node;
• a second electrical path coupled to the voltage source and the node;
• a first transistor having a first gate and a first channel, wherein the first path includes the first channel and the first gate adapted to receive a reference voltage;
• a second transistor having a second gate and a second channel, wherein the first path includes the second channel and the second gate adapted to receive serial data having a voltage level;
• a variable resistor, coupled to the first electrical path and the second electrical path, to provide a predetermined resistance responsive to a control signal;
• and,
• a signal processing circuit, coupled to the variable resistor and the node, to generate a control signal responsive to the node voltage.

17) An apparatus, comprising:

• a transmit circuit to transmit serial data;
• and,
• a receive circuit, coupled to the transmit circuit, to generate an output signal responsive to the serial data, wherein the receive circuit includes:
• a voltage source;
• a current source coupled to a node;
• a first electrical path coupled to the voltage source and the node;
• a second electrical path coupled to the voltage source and the node;
• a first transistor having a first gate and a first channel, wherein the first path includes the first channel and the first gate adapted to receive a reference voltage;
• a second transistor having a second gate and a second channel, wherein the first path includes the second channel and the second gate adapted to receive a data voltage, corresponding the serial data, that is variable as a positive and negative voltage relative to the reference voltage;
• and,
• a variable resistor, coupled to the first electrical path and the second electrical path, to provide a predetermined resistance responsive to a node voltage at the node.

27) A method, comprising the steps of:

• receiving serial data having a voltage level;
• applying the voltage level to a first transistor in a first electrical path;
• applying a reference voltage to a second transistor in a second electrical path;
• wherein the first electronic path is coupled to the second electronic path at a node;
• providing a variable resistance between the first electronic path and the second electronic path responsive to a voltage at the node;
• and,
• outputting an output voltage from the first and second electrical path.