Differential bus receiver with four-quadrant input circuit

A device comprising:

• a bus receiver configured to couple to a two-conductor communication bus and to receive a data signal provided on the two-conductor communication bus, the bus receiver comprising:
• an input stage comprising a four-quadrant input circuit, the four-quadrant input circuit including a first current input configured to be coupled to a first conductor of the two-conductor communication bus, a second current input configured to be coupled to a second conductor of the two-conductor communication bus, and a common mode current input configured to be coupled to both the first conductor and the second conductor of the two-conductor communication bus,
• wherein the four-quadrant input circuit is configured to receive a first current at the first current input from the first conductor, a second current at the second current input from the second conductor, and a common mode current at the common mode current input, compensate the first current and the second current based on the common mode input current input, and output a first differential voltage based on a difference in current flows between the first current and the second current compensated for the common mode current, and output a second differential voltage based on the difference in current flows between the first current and the second current compensated for the common mode current;
• and
• a gain stage coupled to the four-quadrant input circuit,
• wherein the gain stage is configured to receive the first differential voltage and the second differential voltage, generate a first current output based on the first differential voltage, generate a second current output based on the second differential voltage, and output a summed current comprising the first current output and the second current output that is indicative of either a first data state or a second data state present on the two-conductor communication bus.

A device comprising:

• a bus receiver comprising a four-quadrant input circuit, the four-quadrant input circuit including a first current input and a second current input,
• wherein the four-quadrant input circuit is configured to receive a first current at the first current input, receive a second current at the second current input, and output a first differential voltage and a second differential voltage based on a difference in current flows between the first current and the second current, the first differential voltage and the second differential voltage compensated for a common mode current;
• and
• an active gain input stage coupled to the four-quadrant input circuit, the active gain input stage comprising:
• a first input coupled to a voltage input differential circuit;
• a second input coupled to a common mode biasing circuit operable to provide biasing to control biasing of a plurality of output semiconductors controlling a plurality of outputs of the four-quadrant input circuit;
• a first active gain stage output coupled to the common mode biasing circuit;
• and a second active gain stage output coupled to the common mode biasing circuit,
• wherein the active gain input stage is operable to provide common mode current compensation by driving, using the first active gain stage output, the common mode biasing circuit to allow current to be provided to the first current input and the second current input when a negative common mode current exists between the first current input and the second current input;
• and provide common mode current compensation by driving, using the second active gain stage output, the common mode biasing circuit to allow current to be sunk from the first current input and from the second current input when a positive common mode current exists between the first current input and the second current input.

A communication system comprising:

• a serial bus comprising a first conductor and a second conductor configured as a controller area network (CAN) bus;
• and
• a plurality of controller areas network (CAN) nodes coupled the CAN bus, wherein at least one of the CAN nodes comprising a transceiver configured to receive data received from the CAN bus and convert the received data to signal levels usable by a control area network (CAN) controller coupled to the transceiver, and to convert data received from the CAN controller into data signals acceptable for transmission by the CAN bus, wherein the transceiver comprises a bus receiver comprising:
• an input stage comprising a four-quadrant input circuit, the four-quadrant input circuit including a first current input configured to be coupled to a first conductor of the two-conductor communication bus and a second current input configured to be coupled to a second conductor of the two-conductor communication bus,
• wherein the four-quadrant input circuit is configured to receive a first current at the first current input from the first conductor and receive a second current at the second current input from the second conductor, and output a first differential voltage based on a difference in current flows between the first current and the second current, and output a second differential voltage based on the difference in current flows between the first current and the second current;
• and
• a gain stage coupled to the four-quadrant input circuit,
• wherein the gain stage is configured to receive the first differential voltage and the second differential voltage, generate a first current output based on the first differential voltage, generate a second current output based on the second differential voltage, and output a summed current comprising the first current output and the second current output that is indicative of either a first data state or a second data state present on the serial bus.