Radio frequency interference common mode injection in a C-PHY receiver

A method for buffering signals received from a multi-wire serial bus, comprising:

• receiving a first signal over a first wire of a multi-wire serial bus at a gate of a first input transistor, the first input transistor having a source that is coupled to a first voltage rail through a first current source;
• receiving a second signal over a second wire of the multi-wire serial bus at a gate of a second input transistor, the second input transistor having a source that is coupled to the first voltage rail through a second current source;
• and
• injecting common mode noise into the sources of the first input transistor and the second input transistor, using:
• a first injection circuit having a capacitor and three or more resistors, each wire of the multi-wire serial bus being coupled to a first common node through the three or more resistors of the first injection circuit, and the first common node being coupled to the source of the first input transistor through the capacitor of the first injection circuit;
• and
• a second injection circuit having a capacitor and three or more resistors, each wire of the multi-wire serial bus being coupled to a second common node through the three or more resistors of the second injection circuit, and the second common node being coupled to the source of the second input transistor through the capacitor of the second injection circuit;
• wherein each combination of two wires in a three-wire serial bus is coupled to one of three differential receiver circuits.

An apparatus, comprising:

• means for buffering a first signal received over a multi-wire serial bus, including a first input transistor having a gate that is coupled to a first wire of the multi-wire serial bus and a source that is coupled to a first voltage rail through a first current source;
• means for buffering a second signal received over the multi-wire serial bus, including a second input transistor having a gate that is coupled to a second wire of the multi-wire serial bus and a source that is coupled to the first voltage rail through a second current source;
• means for injecting common mode noise into the sources of the first input transistor and the second input transistor, including:
• a first injection circuit having a capacitor and three or more resistors, each wire of the multi-wire serial bus being coupled to a first common node through the three or more resistors of the first injection circuit, and the first common node being coupled to the source of the first input transistor through the capacitor of the first injection circuit;
• and
• a second injection circuit having a capacitor and three or more resistors, each wire of the multi-wire serial bus being coupled to a second common node through the three or more resistors of the second injection circuit, and the second common node being coupled to the source of the second input transistor through the capacitor of the second injection circuit;
• and
• three differential receiver circuits, wherein each combination of two wires in a three-wire serial bus is coupled to one of the three differential receiver circuits.