Line transceiver apparatus for multiple transmission standards

A line transceiver apparatus for multiple transmission standards, comprising:

• an operational amplifier, having an inverting input node, a non-inverting input node, an inverting output node, and a non-inverting output node;
• a first variable resistor unit and a second variable resistor unit, wherein the first variable resistor unit is coupled between the inverting input node and the non-inverting output node, and the second variable resistor unit is coupled between the non-inverting intput node and the inverting output node;
• a transformer unit, wherein a first load node and a second load node of the transformer unit are respectively a first receiving node and a second receiving node of the line transceiver apparatus;
• a third variable resistor unit and a fourth variable resistor unit, wherein the third variable resistor unit is coupled between a first transmission node of the transformer unit and the inverting input node, and the fourth variable resistor unit is coupled between a second transmission node of the transformer unit and the non-inverting input node;
• a fifth variable resistor unit and a sixth variable resistor unit, wherein the fifth variable resistor unit is coupled between the first transmission node and the non-inverting output node, and the sixth variable resistor unit is coupled between the second transmission node and the inverting output node;
• and
• a variable resistor control unit, coupled to the first to sixth variable resistor units, so as to adjust the first to sixth variable resistor units according to a transmission standard selection signal.