Method and device for attenuating oscillations on bus lines of a bus system based on differential voltage signals

An attenuation device for a controller area network bus of a bus system based on differential voltage signals, the bus including a first bus line and a second bus line, comprising:

• an attenuating circuit that provides a variable electrical resistance value between the first bus line and the second bus line and that is operable in at least three circuit states, wherein in a first circuit state, the first bus line and the second bus line are connected by an attenuation resistor having a first resistance value, in a second circuit state the first bus line and the second bus line are connected by the attenuation resistor having a second resistance value, and in a third circuit state the first bus line and the second bus line are connected by the attenuation resistor having a third resistance value;
• wherein the first resistance value is less than the second resistance value, and the second resistance value is less than the third resistance value,
• wherein the attenuating circuit comprises:
• a first field effect transistor (FET) having a predetermined gate source capacitance, a second FET having a predetermined gate source capacitance and a resistor element having a predetermined resistance value, wherein a drain terminal of the first FET is connected to a terminal for the first bus line and a drain terminal of the second FET is connected to a terminal for the second bus line, wherein a source terminal of the first FET and a source terminal of the second FET are connected to a common source terminal point, wherein a gate terminal of the first FET and a gate terminal of the second FET are connected to a common gate terminal point, and wherein the resistor element is connected to the source terminal point and the common gate terminal point.

A method for attenuating oscillations on bus lines of a controller area network bus system based on differential voltage signals, using an attenuation device, the method comprising:

• detecting an edge in a differential voltage signal;
• providing, when the edge is detected, at least one voltage to at least one control terminal, wherein:
• in a first time period, the at least one voltage is provided corresponding to a first circuit state,
• in a second time period that follows the first time period, the at least one voltage is provided corresponding to a second circuit state, and
• in a third time period that is outside of the first and the second time period, the at least one voltage is provided corresponding to a third circuit state, and
• wherein the attenuation device includes:
• an attenuating circuit that provides a variable electrical resistance value between a first bus line of the bus and a second bus line of the bus, and that is operable in at least three circuit states, wherein in the first circuit state, the first bus line and the second bus line are connected by an attenuation resistor having a first resistance value, in the second circuit state the first bus line and the second bus line are connected by the attenuation resistor having a second resistance value, and in the third circuit state the first bus line and the second bus line are connected by the attenuation resistor having a third resistance value, wherein the first resistance value is less than the second resistance value, and the second resistance value is less than the third resistance value.

A control apparatus for an attenuation device for a controller area network bus of a bus system based on differential voltage signals, the bus including a first bus line and a second bus line, comprising:

• terminal elements for connecting to the first and the second bus lines and at least one output, for connecting to the at least one control terminal, and
• wherein the control apparatus that is configured to perform the following:
• detecting an edge in a differential voltage signal;
• providing, when the edge is detected, at least one voltage to at least one control terminal, wherein:
• in a first time period, the at least one voltage is provided corresponding to a first circuit state, and
• in a second time period that follows the first time period, the at least one voltage is provided corresponding to a second circuit state;
• wherein the edge is a falling edge of the differential voltage signal;
• wherein the attenuation device includes:
• an attenuating circuit that provides a variable electrical resistance value between the first bus line and the second bus line and that is operable in at least three circuit states, wherein in the first circuit state, the first bus line and the second bus line are connected by an attenuation resistor having a first resistance value, in the second circuit state the first bus line and the second bus line are connected by the attenuation resistor having a second resistance value, and in a third circuit state the first bus line and the second bus line are connected by the attenuation resistor having a third resistance value, wherein the first resistance value is less than the second resistance value, and the second resistance value is less than the third resistance value;
• and
• a control circuit having the at least one control terminal that switches the attenuating circuit back and forth between the circuit states according to control signals on the at least one control terminal.

An attenuation apparatus, comprising:

• a plurality of attenuation devices, each of the attenuation devices being configured for a controller area network bus of a bus system based on differential voltage signals, the bus including a first bus line and a second bus line;
• wherein each of the attenuation devices include:
• an attenuating circuit that provides a variable electrical resistance value between the first bus line and the second bus line and that is operable in at least three circuit states, wherein in a first circuit state, the first bus line and the second bus line are connected by an attenuation resistor having a first resistance value, in a second circuit state the first bus line and the second bus line are connected by the attenuation resistor having a second resistance value, and in a third circuit state the first bus line and the second bus line are connected by the attenuation resistor having a third resistance value, wherein the first resistance value is less than the second resistance value, and the second resistance value is less than the third resistance value;
• wherein the second resistance value is a time-variable resistance value, and
• wherein the attenuation devices are connected in parallel on the first and second bus lines.

An attenuation apparatus, comprising:

• a plurality of attenuation devices, each of the attenuation devices being configured for a controller area network bus of a bus system based on differential voltage signals, the bus including a first bus line and a second bus line;
• wherein each of the attenuation devices include:
• an attenuating circuit that provides a variable electrical resistance value between the first bus line and the second bus line and that is operable in at least three circuit states, wherein in a first circuit state, the first bus line and the second bus line are connected by an attenuation resistor having a first resistance value, in a second circuit state the first bus line and the second bus line are connected by the attenuation resistor having a second resistance value, and in a third circuit state the first bus line and the second bus line are connected by the attenuation resistor having a third resistance value, wherein the first resistance value is less than the second resistance value, and the second resistance value is less than the third resistance value;
• wherein the attenuation devices are connected in parallel on the first and second bus lines, and
• wherein the attenuating circuit includes:
• a control circuit having at least one control terminal that switches the attenuating circuit back and forth between the circuit states according to control signals on the at least one control terminal;
• wherein the control circuit is connected to the common gate terminal point and the source terminal point of the attenuating circuit and includes a voltage terminal and a reference potential terminal,
• wherein each of the attenuation devices further includes a first field effect transistor (FET) having a predetermined gate source capacitance, a second FET having a predetermined gate source capacitance and a resistor element having a predetermined resistance value,
• wherein a drain terminal of the first FET is connected to a terminal for the first bus line and a drain terminal of the second FET is connected to a terminal for the second bus line,
• wherein a source terminal of the first FET and a source terminal of the second FET are connected to a common source terminal point,
• wherein a gate terminal of the first FET and a gate terminal of the second FET are connected to a common gate terminal point,
• wherein the resistor element is connected to the source terminal point and the common gate terminal point,
• wherein the control circuit, when a voltage is applied to the voltage terminal and a reference potential is applied to the reference potential terminal, is configured to perform the following:
• connecting the source terminal point to the voltage terminal and connect the common gate terminal point to the reference potential terminal when at least one voltage that signals the first circuit state is applied to the at least one control terminal;
• switching the source terminal point and the common gate terminal point open in the control circuit when at least one voltage that signals the second circuit state is applied to the at least one control terminal;
• making a low-resistance connection between the source terminal point and the common gate terminal point when at least one voltage that signals the third circuit state is applied to the at least one control terminal, and
• wherein the predetermined gate source capacitance and/or the predetermined resistance value of different ones of the attenuation devices have different values.

An attenuation apparatus, comprising:

• a plurality of attenuation devices, each of the attenuation devices being configured for a controller area network bus of a bus system based on differential voltage signals, the bus including a first bus line and a second bus line;
• wherein each of the attenuation devices include:
• an attenuating circuit that provides a variable electrical resistance value between the first bus line and the second bus line and that is operable in at least three circuit states, wherein in a first circuit state, the first bus line and the second bus line are connected by an attenuation resistor having a first resistance value, in a second circuit state the first bus line and the second bus line are connected by the attenuation resistor having a second resistance value, and in a third circuit state the first bus line and the second bus line are connected by the attenuation resistor having a third resistance value, wherein the first resistance value is less than the second resistance value, and the second resistance value is less than the third resistance value;
• wherein the attenuation devices are connected in parallel on the first and second bus lines, and
• a plurality of control apparatuses, each of the control apparatuses including:
• terminal elements for connecting to the first and the second bus lines and at least one output, for connecting to the at least one control terminal, and for performing the following:
• detecting an edge in a differential voltage signal;
• providing, when the edge is detected, at least one voltage to the at least one control terminal, wherein:
• in a first time period, the at least one voltage is provided corresponding to the first circuit state, and
• in a second time period that follows the first time period, the at least one voltage is provided corresponding to the second circuit state;
• wherein the edge is a falling edge of the differential voltage signal, and
• wherein each of the control apparatuses is connected to one of the plurality of attenuation devices, wherein the first and/or second predetermined time period of at least two different control apparatuses is different for each of the control apparatuses.