Current steering output circuit with switchable shunt resistor

A current steering output circuit having first and second output nodes, and a plurality of current driver circuits, each said current driver circuit comprising:

• a current driver generating a current;
• a switching arrangement connecting said current driver to said first and second output nodes;
• and
• a switchable shunt resistor connected across said current driver and being switchable from a non-conductive state to a resistive conductive state;
• wherein
• in a first data state, said current driver is connected to said first and second output nodes by said switching arrangement and said switchable shunt resistor is in the non-conductive state so that said current will flow through a load connected across said output nodes;
• and
• in a second data state, said current driver is disconnected from said output nodes by said switching arrangement and said switchable shunt resistor is in said resistive, conducting state, so that said current flows through said switchable shunt resistor.

An integrated circuit that includes a current driving circuit having first and second output nodes and first and second shunt nodes, said current driving circuit comprising:

• a current driver generating a current;
• a first switching arrangement connecting said current driver to said first and second output nodes;
• and
• a second switching arrangement connecting said current driver to said first and second shunt nodes;
• wherein
• in a first data state, said current driver is connected to said first and second output nodes by said first switching arrangement and disconnected from said first and second shunt nodes by said second switching arrangement so that said current will flow through a load connected across said output nodes;
• and
• in a second data state, said current driver is disconnected from said output nodes by said first switching arrangement and connected to said shunt nodes by said second switching arrangement so that said current will flow through a resistance connected across said shunt nodes.

A current output circuit having first and second output nodes, said circuit comprising:

• a first current driver generating a first current;
• a current switch connecting said first current driver to said first and second output nodes, wherein in a first data state, said first current will flow from said first output node to said second output node when a load is connected to said output nodes and in a second data state, said first current will flow from said second output node to said first output node when said load is connected across said output nodes;
• a second current driver generating a second current;
• a switchable shunt resistance connected across said second current driver and being switchable from a non-conductive state to a resistive conductive state;
• and
• a switching assembly selectively connecting said second current driver to said first and second output nodes;
• wherein
• in the first data state, said second current driver is connected to said first and second output nodes by said switching assembly so that said second current will flow from said first output node to said second output node when said load is connected across said output nodes and said switchable shunt resistance is in the non-conductive state;
• and
• in the second data state, said second current driver is disconnected from said output nodes by said switching assembly and said switchable shunt resistance resistor is in a resistive conducting state, wherein said second current flows through said switchable shunt resistance resistor.

An integrated circuit that includes an asymmetric current output circuit having first and second output nodes, said current output circuit comprising:

• a first current source;
• a first switch connected between said first current source and said first output node;
• a second switch connected between said first current source and said second output node;
• a first current sink;
• a third switch connected between said first output node and said first current sink;
• a fourth switch connected between said second output node and said first current sink;
• a second current source;
• a fifth switch connected between said second current source and said first output node;
• a second current sink;
• a sixth switch connected between said second output node and said second current sink;
• and
• a switchable shunt resistance connected between said second current source and said second current sink and which is either in a non-conductive state or in a resistive conductive state.