US 7,804,188 B2Granted

Termination circuit, vehicle-mounted control apparatus, and vehicle-mounted communication system

AssigneeDenso Corporation

InventorsNaoto Sakai, Kouji Kondoh

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Abstract

The termination circuit for use in a transmission line to transmit a differential signal includes a first series circuit of a resistive element and an inductive element connected between one of two signal wires of the transmission line and a reference potential, and a second series circuit of a resistive element and an inductive element connected between the other of the signal wires and the reference potential. The inductive elements of the first and second series circuits are magnetically coupled such that they generate magnetic fields having such directions as to reinforce each other when a common-mode signal flows along the transmission line, and generate magnetic fields having such directions as to weaken each other when a differential-mode signal flows along the transmission line.

Claims17

Dependent claims

A termination circuit for use in a transmission line constituted by a first signal wire and a second signal wire to transmit a differential signal comprising:

a first series circuit of a first resistive element and a first inductive element, one end of said first resistive element being connected to said first signal wire, the other end of said first resistive element being connected to one end of said first inductive element, the other end of said first inductive element being applied with a reference voltage;
a second series circuit of a second resistive element and a second inductive element, one end of said second resistive element being connected to said second signal wire, the other end of said second resistive element being connected to one end of said second inductive element, the other end of said second inductive element being applied with said reference voltage;
and
a reference potential generating circuit generating, as said reference voltage, a potential equivalent to a center potential of said differential signal, wherein said reference potential generating circuit includes a voltage dividing circuit for dividing a power supply voltage to generate said reference voltage;
said first and second inductive elements being magnetically coupled such that said first and second inductive elements generate magnetic fields having such directions as to reinforce each other when a common-mode signal flows along said transmission line, and generate magnetic fields having such directions as to weaken each other when a differential-mode signal flows along said transmission line.

2 more elements

A vehicle-mounted control apparatus comprising:

a transmit/receive circuit having a capability of exchanging a differential signal with another vehicle-mounted control apparatus through a transmission line constituted by a first signal wire and a second signal wire;
and
a termination circuit connected to said transmission line;
said termination circuit including:
a first series circuit of a first resistive element and a first inductive element, one end of said first resistive element being connected to said first signal wire, the other end of said first resistive element being connected to one end of said first inductive element, the other end of said first inductive element being applied with a reference voltage;
a second series circuit of a second resistive element and a second inductive element, one end of said second resistive element being connected to said second signal wire, the other end of said second resistive element being connected to one end of said second inductive element, the other end of said second inductive element being applied with said reference voltage;
and
a reference potential generating circuit generating, as said reference voltage, a potential equivalent to a center potential of said differential signal, wherein said reference potential generating circuit includes a voltage dividing circuit for dividing a power supply voltage to generate said reference voltage;
said first and second inductive elements being magnetically coupled such that said first and second inductive elements generate magnetic fields having such directions as to reinforce each other when a common-mode signal flows along said transmission line, and generate magnetic fields having such directions as to weaken each other when a differential-mode signal flows along said transmission line.

6 more elements

A vehicle-mounted communication system comprising:

a transmission line constituted by a first signal wire and a second signal wire;
a plurality of vehicle-mounted control apparatuses, each one of which includes a transmit/receive circuit having a capability of exchanging a differential signal with other said vehicle-mounted control apparatuses through said transmission line;
and
a termination circuit connected to said transmission line;
said termination circuit including:
a first series circuit of a first resistive element and a first inductive element, one end of said first resistive element being connected to said first signal wire, the other end of said first resistive element being connected to one end of said first inductive element, the other end of said first inductive element being applied with a reference voltage;
a second series circuit of a second resistive element and a second inductive element, one end of said second resistive element being connected to said second signal wire, the other end of said second resistive element being connected to one end of said second inductive element, the other end of said second inductive element being applied with said reference voltage;
and
a reference potential generating circuit generating, as said reference voltage, a potential equivalent to a center potential of said differential signal, wherein said reference potential generating circuit includes a voltage dividing circuit for dividing a power supply voltage to generate said reference voltage;
said first and second inductive elements being magnetically coupled such that said first and second inductive elements generate magnetic fields having such directions as to reinforce each other when a common-mode signal flows along said transmission line, and generate magnetic fields having such directions as to weaken each other when a differential-mode signal flows along said transmission line.

7 more elements

A vehicle-mounted communication system comprising:

a transmission line constituted by a first signal wire and a second signal wire;
a plurality of vehicle-mounted control apparatuses, each one of which includes a transmit/receive circuit having a capability of exchanging a differential signal with other said vehicle-mounted control apparatuses through said transmission line;
and
a termination circuit connected to said transmission line;
said termination circuit including:
a first series circuit of a first resistive element and a first inductive element, one end of said first resistive element being connected to said first signal wire, the other end of said first resistive element being connected to one end of said first inductive element, the other end of said first inductive element being applied with a reference voltage;
a second series circuit of a second resistive element and a second inductive element, one end of said second resistive element being connected to said second signal wire, the other end of said second resistive element being connected to one end of said second inductive element, the other end of said second inductive element being applied with said reference voltage;
and
a reference potential generating circuit generating, as said reference voltage, a potential equivalent to a center potential of said differential signal;
wherein said reference potential generating circuit includes a voltage dividing circuit for dividing a power supply voltage to generate said reference voltage.

7 more elements

Dependencies are inferred from the claim text.