JP4193060B2 - Electronic circuit - Google Patents

Description

  The present invention relates to an electronic circuit that can suitably perform communication between substrates such as an IC (Integrated Circuit) bare chip and a PCB (printed circuit board).

  The present inventors have system-in-package (SiP) in which a plurality of bare chips are encapsulated in one LSI (Large Scale Integration) package by a method in which chips are three-dimensionally mounted and the chips are electrically connected by inductive coupling. Has been proposed (see Patent Document 1).

  FIG. 3 is a diagram showing the configuration of the electronic circuit of the invention of the prior application. The electronic circuit includes first to third LSI chips 31a to 31c. In this example, LSI chips are stacked in three layers to form a bus extending over three chips. That is, one communication channel that can communicate with each other between three parties (three LSI chips) is configured. First to third LSI chips 31a to 31c are stacked vertically, and the respective chips are fixed to each other with an adhesive. On the first to third LSI chips 31a to 31c, first to third transmission coils 33a to 33c used for transmission are formed by wiring, respectively, and first to third reception coils 35a to 35c used for reception are respectively formed. 35c is formed by wiring. These three pairs of transmitting and receiving coils 33 and 35 are arranged on the first to third LSI chips 31a to 31c so that the centers of the openings coincide with each other. As a result, the three pairs of transmitting and receiving coils 33 and 35 form inductive coupling, and communication is possible. The first to third transmission circuits 33a to 33c are connected to the first to third transmission circuits 32a to 32c, respectively, and the first to third reception coils 35a to 35c are respectively connected to the first to third reception circuits 34a to 34c. Is connected. The transmission / reception coils 33 and 35 are mounted as three-dimensional or more coils in a three-dimensional manner within the area allowed for communication, utilizing multilayer wiring of process technology. The transmission / reception coils 33 and 35 have an optimum shape for communication, and it is necessary to take an optimum number of turns, openings, and line widths. Generally, the transmission coil 33 is smaller than the reception coil 35.

FIG. 4 is a diagram showing a configuration example of a transmission circuit used in the electronic circuit of the prior invention. This transmission circuit includes a delay buffer 41 and transistors T7 to T10. The transistors T7 and T8, and the transistors T9 and T10 form inverters, function as buffers, and drive the transmission coil 42. When the input transmission data Txdata goes from low to high, it is inverted by the transistors T7 and T8, the current IT is passed through the transmission coil 42, delayed by the delay buffer 41, inverted by the transistors T9 and T10, and inverted by the transmission coil 42. Stop the current IT. As a result, a triangular wave-shaped pulse current is caused to flow through the transmission coil 42. When the transmission data Txdata changes from high to low, a pulse current having a reverse triangular wave shape is caused to flow through the transmission coil 42.
Japanese Patent Application No. 2004-037242

  However, in the case of the transmission circuit described above, both ends of the transmission coil 42 are in a short circuit state while the transmission coil 42 is not transmitting, that is, while no current is flowing through the transmission coil 42. While the other transmission coils constituting the signal are transmitting signals, the induced current in the transmission coil 42 interferes with the change in the magnetic field and attenuates the received signal.

  The present invention has been made in view of the above problems, and an object thereof is to provide an electronic circuit capable of suppressing interference to communication by a transmission coil not transmitting a signal when inter-board communication is realized by inductive coupling. To do.

An electronic circuit of the present invention includes a first receiving coil that is formed by wiring on a substrate and receives a signal, a first receiving circuit that inputs a signal from the first receiving coil, and the first receiving coil by wiring on the substrate. A first transmission coil that is formed at a position where it is inductively coupled to the first transmission coil, and outputs a signal to the first transmission coil and opens the first transmission coil while the first reception circuit is receiving the signal . A first substrate having one transmitter circuit, a second receiver coil that is formed at a position corresponding to the first transmitter coil by wiring on the substrate to form a communication channel and receive a signal; and from the second receiver coil A second receiving circuit for inputting a signal and an inductive coupling with the second receiving coil by a wiring on the substrate are formed at a position corresponding to the first receiving coil to form a communication channel between the first receiving coil and the signal. Second transmission to send During a coil, wherein the output signals to the second transmission coil second receiver circuit is receiving a signal and a second substrate having a second transmission circuit for opening the second transmission coil.

According to the present invention, when inter-board communication is realized by inductive coupling, it is possible to easily determine when to open the transmission coil and to suppress interference to communication by the transmission coil not transmitting a signal. .

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

  1 is a diagram illustrating a configuration of a transmission circuit in an electronic circuit according to a first embodiment of the present invention. This transmission circuit includes a delay buffer 11, NOT12, NAND13, NOR14, and transistors T1 to T4, and drives the transmission coil 15. The delay buffer 11 and the transistors T1 to T4 are the same as the delay buffer 41 and the transistors T7 to T10 described as the prior art, and detailed description thereof is omitted. The signal Tx / bar (Rx) is a signal that is high when transmitting and low when receiving, assuming that this chip is receiving when this chip is not transmitting for this communication channel. It is. As a result, when the chip is not transmitting (in this embodiment 1, that is, when receiving), since the signal Tx / bar (Rx) is low, the output of the NOT 12 is high and the output of the NAND 13 Is high and the output of the NOR 14 is low, turning off the transistors T3 and T4 and opening the transmission coil 15. For this reason, the transmission coil 15 does not interfere with the change of the magnetic field and does not attenuate the reception signal.

  FIG. 2 is a diagram illustrating a configuration of a transmission circuit in an electronic circuit according to the second embodiment of the present invention. This transmission circuit includes NOT 21, NAND 22, NOR 23, transistors T 5 and T 6, and a capacitor 25, and drives the transmission coil 24. NOT21, NAND22, and NOR23 are the same as NOT12, NAND13, and NOR14 of the first embodiment, and detailed description thereof is omitted. The capacitor 25 can be easily manufactured by using the capacitance of the MOS transistor. At the time of transmission, that is, when Tx / bar (Rx) is high, when the input transmission data Txdata goes from low to high, the transistor T5 turns from off to on, and the transistor T6 turns from on to off, A current IT flows through the transmission coil 24 and charges the capacitor 25. When the capacitor 25 is fully charged, the current IT stops, and eventually, a triangular wave-shaped pulse current flows through the transmission coil 24. Next, when the transmission data Txdata goes from high to low, the transistor T5 turns from on to off and the transistor T6 turns from off to on, and the current IT flows in the transmission coil 24 in the reverse direction, discharging the capacitor 25. When the capacitor 25 is sufficiently discharged, the current IT stops and a pulse current having a triangular wave shape with a reverse polarity flows through the transmission coil 24. In the case of the second embodiment, since the discharge of the capacitor 25 is used to flow the pulse current having the reverse polarity and the power supply current is not used, power can be saved. Further, since the delay buffer 11 can be omitted and the two buffers (T1 to T4) for driving the transmission coil 24 can be made one (T5, T6), power can be further saved. In addition, since the charge / discharge current when charging / discharging the capacitor via the coil has good linearity, a large signal can be transmitted from the transmission coil 24 with a small current, and power can be saved also in this respect.

  In addition, this invention is not limited to the said Example.

  When there are a plurality of transmission coils in one communication channel, each transmission coil is opened while the other transmission coil is transmitting, and a transmission coil not transmitting interferes with other communications. That is the essence of the present invention.

  You may decide to open | release the transmission coil which is not transmitting.

  In the case of two-party communication such as communication between two chips, the transmission coil may be opened during reception.

  As for a communication channel between three or more parties, there may be a board on which only a transmission coil is mounted without a reception coil on a certain board related to the communication channel. Even in that case, the transmitting coil is opened while the other transmitting coil is transmitting.

It is a figure which shows the structure of the transmission circuit in the electronic circuit by Example 1 of this invention. It is a figure which shows the structure of the transmission circuit in the electronic circuit by Example 2 of this invention. It is a figure which shows the structure of the electronic circuit of prior invention. It is a figure which shows the structural example of the transmission circuit used for the electronic circuit of prior application invention.

Explanation of symbols

11 Delay buffer 12 NOT
13 NAND
14 NOR
15 Transmitting coil 21 NOT
22 NAND
23 NOR
24 transmission coil 25 capacitor 31 LSI chip 32 transmission circuit 33 transmission coil 34 reception circuit 35 reception coil 41 delay buffer 42 transmission coils T1 to T10 transistor Txdata transmission data

Claims (1)

A first receiving coil that is formed by wiring on the substrate and receives a signal, a first receiving circuit that inputs a signal from the first receiving coil, and a position that is inductively coupled to the first receiving coil by wiring on the substrate A first transmission coil that transmits a signal and a first transmission circuit that outputs a signal to the first transmission coil and opens the first transmission coil while the first reception circuit receives the signal . 1 substrate,
A second receiving coil which is formed at a position corresponding to the first transmitting coil by wiring on the substrate to form a communication channel and receives a signal; a second receiving circuit which inputs a signal from the second receiving coil; and a substrate A second transmitter coil that is inductively coupled to the second receiver coil by the upper wiring, is formed at a position corresponding to the first receiver coil, forms a communication channel with the first receiver coil, and transmits a signal; An electronic circuit comprising: a second substrate having a second transmission circuit that outputs a signal to a transmission coil and opens the second transmission coil while the second reception circuit receives the signal .

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