WIRELESS COMMUNICATION SYSTEM AND WIRELESS COMMUNICATION APPARATUS
A first communication device includes a first coupling element and a second communication device includes a second coupling element. The first and second communication devices are configured to wirelessly transmit, between the first and second communication devices, a differential-mode signal and a common-mode signal simultaneously through non-contact coupling between the first and second coupling elements.
1 . A wireless communication system comprising:
first and second communication devices;
a first coupling element connected to the first communication device through a first signal line pair; and
a second coupling element connected to the second communication device through a second signal line pair, wherein
the first and second communication devices are configured to wirelessly transmit, between the first and second communication devices, a differential-mode signal and a common-mode signal simultaneously through non-contact coupling between the first and second coupling elements.
2 . The wireless communication system according to claim 1 , wherein
the differential-mode signal is a baseband signal, and
the common-mode signal is a modulated carrier wave signal.
3 . The wireless communication system according to claim 1 , wherein
the differential-mode signal is a baseband signal, and
the common-mode signal is a sine wave signal, or a band-limited rectangular-wave signal whose bandwidth is limited in comparison to that of the baseband signal.
4 . The wireless communication system according to claim 1 , wherein
the first coupling element comprises a first inductor including a first conductive loop,
the second coupling element comprises a second inductor including a second conductive loop, and
the first and second coupling elements are arranged so that the first and second conductive loops face each other, and thereby form the non-contact coupling.
5 . A wireless communication apparatus comprising:
a first communication device; and
a first coupling element connected to the first communication device through a first signal line pair, wherein
the first communication device is configured to perform simultaneous wireless transmission of a differential-mode signal and a common-mode signal with another wireless communication apparatus through non-contact coupling between the first coupling element and a second coupling element provided in the anther wireless communication apparatus.
6 . The wireless communication apparatus according to claim 5 , wherein
the differential-mode signal is a baseband signal, and
the common-mode signal is a modulated carrier wave signal.
7 . The wireless communication apparatus according to claim 5 , wherein
the differential-mode signal is a baseband signal, and
the common-mode signal is a sine wave signal, or a band-limited rectangular-wave signal whose bandwidth is limited in comparison to that of the baseband signal.
8 . The wireless communication apparatus according to claim 7 , wherein a center frequency of the carrier wave signal, the sine wave signal, or the band-limited rectangular-wave signal is substantially equal to a half of a bit-rate of the baseband signal or substantially equal to an integral multiple of the half of the bit-rate of the baseband signal.
9 . The wireless communication apparatus according to claim 8 , wherein a phase of the carrier wave signal, the sine wave signal, or the band-limited rectangular-wave signal is shifted from a phase of the baseband signal by 90 electrical degrees.
10 . The wireless communication apparatus according to claim 5 , wherein the first communication device comprises:
at least one of a differential-mode transmitter that supplies the differential-mode signal to the first signal line pair and a differential-mode receiver that receives the differential-mode signal from the first signal line pair; and
at least one of a common-mode transmitter that supplies the common-mode signal to the first signal line pair and a common-mode receiver that receives the common-mode signal from the first signal line pair.
11 . The wireless communication apparatus according to claim 5 , wherein
the first coupling element comprises a first inductor including a first conductive loop,
the second coupling element comprises a second inductor including a second conductive loop, and
the first coupling element is disposed so that the first and second conductive loops face each other, and thereby forms the non-contact coupling.
12 . The wireless communication apparatus according to claim 11 , wherein
the first communication device is configured to drive both ends of the first conductive loop by two signals having mutually-opposite phases and constituting the differential-mode signal, or is configured to receive the differential-mode signal from both ends of the first conductive loop, and
the first communication device is further configured to drive both ends of the first conductive loop by two signals having the same phase and constituting the common-mode signal, or is configured to receive the common-mode signal from both ends of the first conductive loop.
13 . The wireless communication apparatus according to claim 11 , wherein the first inductor is formed by a printed wiring on a wiring board, a lead frame inside a semiconductor package, or a wiring layer on a semiconductor substrate.
14 . The wireless communication apparatus according to claim 11 , wherein
each of the first and second conductive loops has an axial-symmetric shape, and
the first inductor is arranged so that a plane containing a symmetry axis of the first conductive loop is in parallel with a plane containing a symmetry axis of the second conductive loop.
15 . The wireless communication apparatus according to claim 14 , wherein the first conductive loop has an identical shape to that of the second conductive loop.
16 . The wireless communication apparatus according to claim 5 , wherein
the non-contact coupling includes inductive coupling and capacitive coupling,
the differential-mode signal is transmitted mainly by the inductive coupling between the first and second coupling elements, and
the common-mode signal is transmitted mainly by the capacitive coupling between the first and second coupling elements.
17 . The wireless communication apparatus according to claim 5 , wherein the first communication device is configured to wake up a circuit for transmitting or receiving the differential-mode signal in response to successful transmission of the common-mode signal.
18 . The wireless communication apparatus according to claim 5 , wherein the first communication device is configured to transmit or receive, by using the common-mode signal, control data used for a transmission power adjustment of the differential-mode signal.
19 . The wireless communication apparatus according to claim 17 , wherein the wireless communication apparatus is configured to display, on a display device, information for urging a user to adjust an arrangement of the wireless communication apparatus or an arrangement of the another wireless communication apparatus, in response to insufficient reception quality of the common-mode signal or the differential-mode signal.
20 . The wireless communication apparatus according to claim 10 , wherein the common-mode receiver comprises a rectifier that rectifies the common-mode signal received by the common-mode receiver.