JP7249211B2 - Wireless device wake-up circuit - Google Patents

Description

The present invention relates to wake-up circuitry for wireless devices.

For example, in order for all things represented by the International Organization of Employers (IoE) to exchange large amounts of data in a wireless system, a compact and low power consumption wireless system is required. Recently, 60 GHz band wireless devices are being actively developed. A wireless device used in such a wireless system uses a wakeup circuit to wake up the main circuit. Therefore, the wakeup circuit is also required to be smaller and consume less power.

FIG. 12 is a diagram showing an example of a wakeup circuit of a conventional wireless device. For example, conventionally, as shown in FIGS. 12(A) and 12(C), a λ/4 coupler is provided before and after the LNA, and the wakeup signal is detected by a detection circuit from the output of the λ/4 coupler. Was. Conventionally, for example, as shown in FIG. 12B, a switch switches between RF signal and wakeup signal inputs, and a detection circuit detects the wakeup signal from the output of a separately provided LNA. As described above, the conventional wakeup circuit cannot be miniaturized because it uses a λ/4 coupler, a switch, and an LNA for the input of the detection circuit.

Japanese Patent Application Laid-Open No. 2007-258901

SUMMARY OF THE INVENTION It is an object of the present invention to provide a wireless device wakeup circuit that can be miniaturized using a millimeter wave band.

In order to solve the above-described problems and achieve the object, the present invention provides a wake-up circuit for a wireless device that amplifies an RF signal input from an antenna with an LNA and then demodulates the RF signal, comprising: A transformer provided between the amplifiers or on the output side of the amplifiers, functioning as a matching circuit, and having a detection coil for detecting a wakeup signal; and a detection circuit that detects and outputs a wakeup signal from an RF signal of a wakeup beacon.

Further, according to one aspect of the present invention, the transformer may be a Trifilar Transformer.

Further, according to one aspect of the present invention, the amplifier may be an LNA (Low Noise AMP).

Further, according to one aspect of the present invention, the detection circuit compares a detection circuit that detects the output of the detection coil, the output of the detection circuit, and a reference voltage, and uses the comparison result as the wake-up signal. and a comparator that outputs as a signal.

Further, according to one aspect of the present invention, the detection circuit and/or the amplifier may operate intermittently.

Also, according to one aspect of the present invention, the other communication device may be a base station.

According to the present invention, it is possible to miniaturize the wakeup circuit of a wireless device that uses the millimeter wave band.

FIG. 1 is a diagram showing a configuration example of a radio system according to this embodiment. FIG. 2 is a diagram for explaining a Wake-Up beacon (signal) transmitted from the base station in FIG. FIG. 3 is a diagram showing a schematic configuration example of a wireless device according to this embodiment. 4 is a diagram illustrating an example of a timing chart of the wireless device of FIG. 3. FIG. FIG. 5 is a diagram showing a first configuration example of the wakeup circuit of FIG. FIG. 6 is a diagram showing a second configuration example of the wakeup circuit of FIG. FIG. 7 is a diagram showing an example of intermittent operation timing of the second configuration example of the wakeup circuit of FIG. FIG. 8 is a diagram showing a third configuration example of the wakeup circuit of FIG. FIG. 9 is a diagram showing a fourth configuration example of the wakeup circuit of FIG. FIG. 10 is a diagram showing a circuit configuration example of the detection circuit of FIG. 11 is a diagram showing a timing chart of a fourth configuration example of the wakeup circuit of FIG. 9. FIG. FIG. 12 is a diagram showing an example of a wakeup circuit of a conventional wireless device.

Embodiments of wakeup circuits for wireless devices according to the present invention will be described in detail below with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, components in the following embodiments include those that can be easily assumed by those skilled in the art or substantially the same components. While the components of the present invention are generally illustrated in the drawings herein, it will be readily appreciated that they may be arranged and designed in a wide variety of different configurations. Accordingly, the following more detailed description of apparatus embodiments of the invention is not intended to limit the scope of the invention as set forth in the claims, but is merely illustrative of selected embodiments of the invention. be. This specification incorporates known technology by reference. As such, one of ordinary skill in the art will understand that the present invention can be implemented without one or more of the specific details, or with other methods, components, materials, using known techniques.

[1. Configuration example of wireless system]
In wireless systems, an event-driven type wake-up or the like is used. In the present embodiment, a compact, low-power-consumption, event-driven wakeup circuit using a millimeter wave band is provided by a transformer having a detection coil for detecting a wakeup signal (for example, a Trifilar Transformer). realized by using

FIG. 1 is a diagram showing an example of a radio system according to this embodiment. A wireless system 1 according to the present embodiment, as shown in FIG. 1, includes a base station 2 and wireless devices 3 such as smart phones, mobile phone terminals, and tablets. The base station 2 and wireless devices 3 . . . communicate using, for example, a millimeter wave band (eg, 60 GHz band).

The base station 2 transmits an RF signal of a Wake-Up beacon (Beacon) for waking up the wireless device 3 . The base station 2 is for transmitting predetermined data (eg, big data) to the wireless device 3, for example.

FIG. 2 is a diagram for explaining a Wake-Up beacon (signal) transmitted from a base station. As shown in FIG. 2, the base station 2 outputs an RF signal of a Wake-Up beacon in a millimeter wave band having a width of T1 and an idle period of T2.

When the wireless device 3 approaches the base station 2 while in a power saving standby state (also referred to as “Wake-Up mode”), the FR signal of the Wake-Up beacon sent from the base station 2 A Wake-Up signal is detected to wake up the transceiver or the like of the wireless device 3 to shift to a normal state (also referred to as "receiving mode") in which communication is possible.

For example, when the wireless device 3 approaches the base station 2, the wireless device 3 detects a Wake-Up signal from the RF signal of the Wake-Up beacon output from the base station 2 and wakes up the transceiver or the like. Thereafter, communication is performed between the base station 2 and the Wake-Up wireless device 3 , and for example, the wireless device 3 can download predetermined data (eg, big data) from the base station 2 . Thus, the wireless device 3 can instantly download desired data simply by approaching the base station 2 .

[2. Configuration example of wireless device]
FIG. 3 is a diagram showing a schematic configuration example of the wireless device 3. As shown in FIG. Broadly speaking, the wireless device 3 includes a wireless module 10 for wireless communication and a battery 20 for supplying power to each part of the wireless module 10 .

The wireless module 10 includes an antenna 11, a transceiver 12, a Wake-Up circuit 13, a detection circuit 14 constituting the Wake-Up circuit 13, a control unit 15, a first LDO (linear regulator) 16, and a 2 LDOs (linear regulators) 17 are provided.

The battery 20 is, for example, a storage battery such as a lithium ion battery, and supplies power to the control unit 15, the first LDO 16, and the second LDO 17.

The first LDO 16 operates permanently, converts the power supplied from the battery 20 to a predetermined voltage level, and outputs the voltage to the detection circuit 14 .

The second LDO 17 operates in response to the Wake-ON signal from the control unit 15 , converts the power supplied from the battery 20 to a predetermined voltage level, and outputs the voltage to the transceiver 12 . Since the second LDO 17 does not supply power to the transceiver 12 in the standby state, power consumption in the transceiver 12 can be reduced.

Transceiver 12 is circuitry used to communicate data. Since the transceiver 12 is not supplied with power from the second LDO 17 in the standby state, only passive elements such as a trifiler transformer and circuits connected to the first LDO 16 can operate. On the other hand, when the Wake-ON signal is input to the transceiver 12 in the standby state, the power is supplied from the second LDO 17 to operate the active elements and enter a normal state in which communication is possible.

Transceiver 12 includes LNAs, matching circuits with trifilar transformers, modulators, demodulators, local oscillators, filters, and the like. The transceiver 12 modulates transmission data generated by the control unit 15 using a predetermined method to generate a transmission signal (RF signal), and transmits the transmission signal via the antenna 11 . Also, the transceiver 12 receives a reception signal (RF signal) via the antenna 11 and outputs reception data obtained by demodulating the reception signal by a predetermined method to the control unit 15 . As a modulation/demodulation method, for example, a superheterodyne method or a direct conversion method can be used.

The wake-up circuit 13 is composed of a detection circuit 14 and a detection coil of the trifilar transformer of the transceiver 12 (see FIG. 5). Since the detection circuit 14 is always powered by the first LDO 16, it operates permanently. Since the Trifiler Transformer is a passive device, it can operate without power.

The Wake-Up circuit 13 is always activated, and uses the detection coil of the trifilar transformer of the transceiver 12 to detect the Wake-Up signal from the RF signal transmitted from the base station 2 and send it to the control unit 15. Output.

The control unit 15 is composed of a microcomputer or the like including a processor and a recording medium storing a program for operating the processor. The control unit 15 controls the entire wireless device 3, and has a function of performing power control and communication control.

For example, the control unit 15 shifts from the normal state to the standby state under a predetermined condition (for example, when the wireless device 3 is not operated by an operation unit (not shown) for a predetermined time), and in the standby state, the Wake-Up circuit is activated. When the Wake-Up signal is input from 13, it shifts to the normal state. Specifically, when the Wake-Up signal is input from the Wake-Up circuit 13, the control unit 15 sends out the Wake-ON signal to the second LDO 17 and the transceiver 12, and the second LDO 17 and the transceiver 12 start up.

FIG. 4 is a diagram showing an example of a timing chart of the wireless device 3 of FIG. 3 above. In the figure, (A) is the RF signal, (B) is the Wake-Up signal, (C) is the Wake-ON signal, and (D) is the state of the transceiver 12. FIG.

For example, when an RF signal as shown in (A) is input from the base station 2, the Wake-Up circuit 13 detects a Wake-Up signal as shown in (B) from the RF signal and outputs it to the control unit 15. do.

When the Wake-Up signal is input, the control unit 15 outputs the Wake-ON signal as shown in (C) to the second LDO 17 and the transceiver 12 . When the Wake-ON signal is input, the transceiver 12 shifts to the normal state and becomes capable of transmitting and receiving data, as shown in (D).

For example, after shifting to the normal state, the control unit 15 may perform various authentication operations with the base station 2, recognize that the signal is a desired signal, and then perform data communication (for example, downloading big data). Also, if the signal is not the desired signal, the wireless device 3 may be shifted to the standby state again.

[3. First Configuration Example of Wake-Up Circuit]
FIG. 5 is a diagram showing a first configuration example of the Wake-Up circuit 13 of FIG. As shown in FIG. 5, by using a trifiler transformer 22 in the matching circuit of the LNA (Low Noise Amplifier) 21 of the antenna 11 and the transceiver 12, when detecting the wake-up signal, compared to the conventional type Miniaturization has been achieved. As shown in FIG. 5, the detection circuit 14 has a detection circuit 31 and a comparator 32 .

The Wake-Up circuit 13 is provided between the antenna 11 and the LNA 21 and functions as an impedance matching circuit between the antenna 11 and the LNA 21. The input side coil P1 (first winding) to which the RF signal is input, and the RF signal to the LNA 21 output side coil P2 (second winding) to output to, a trifilar transformer 22 including a detection coil P3 (third winding) for detecting the Wake-Up signal, and the output of the detection coil P3 is detected and a comparator 32 that compares the output of the detection circuit 31 with a reference voltage Vref and outputs the comparison result to the control unit 15 as a Wake-Up signal. By mounting the trifilar transformer 22 functioning as a matching circuit and for Wake-Up signal detection in this way, it is possible to downsize the configuration for Wake-Up signal detection.

In the trifilar transformer 22, one end of the input side coil P1 is connected to the antenna 11, and the other end is connected to the ground. Both ends of the output side coil P2 are connected to differential input terminals of the LNA 21 . One end of the detection coil P3 is connected to the detection circuit 31, and the other end is connected to the ground via the capacitor C. As shown in FIG.

Next, the operation of detecting the Wake-Up signal from the RF signal in the standby state will be described. An RF signal input from the antenna 11 is impedance-matched by the input side coil P1 and the output side coil P2 of the trifilar transformer 22 and differentially input to the LNA 21 .

On the other hand, the RF signal output from the detection coil P3 is detected by the detection circuit 31, and the detection output is output to the comparator 32. FIG. The comparator 32 receives the detected output and the reference voltage Vref, compares the detected output with the reference voltage Vref, and outputs the comparison result to the control unit 15 as a Wake-Up signal.

[4. Second Configuration Example of Wake-Up Circuit]
FIG. 6 is a diagram showing a second configuration example of the Wake-Up circuit 13 of FIG. In FIG. 6, parts having functions equivalent to those in FIG. In FIG. 6, in the second configuration example of the Wake-Up circuit 13, in the first configuration example shown in FIG. Low power consumption is achieved by making the device operate.

FIG. 7 is a diagram illustrating an example of intermittent operation timing. In FIG. 7, as shown in (A), the period of the Wake-Up beacon transmitted from the base station 2 is, for example, width=10 μsec and pause period=50 μsec. In this case, the period of the intermittent operation of the detection circuit 31 by the Enable Control signal is set to, for example, an operation period of 110 μsec and a rest period of 1 msec. good.

[5. Third Configuration Example of Wake-Up Circuit]
FIG. 8 is a diagram showing a third configuration example of the Wake-Up circuit 13 of FIG. In FIG. 8, in the third configuration example of the Wake-Up circuit 13, by using the trifiler transformer 22 in the subsequent stage of the LNA 21, that is, in the matching circuit of the output of the LNA 21, miniaturization and higher sensitivity than the conventional type is realized. A Balun transformer 23 as a matching circuit is arranged between the antenna 11 and the LNA 21 .

By arranging the trifiler transformer 22 in the subsequent stage of the LNA 21 in this way, the Wake-Up signal can be detected with high sensitivity. In the third configuration example, power is supplied from the second LDO 17 (see FIG. 3) to the LNA 21 even in the standby state, and the LNA 21 is operable. The configurations and operations of the detection circuit 31 and the comparator 32 are the same as those of the first configuration example, and thus descriptions thereof are omitted.

[6. Fourth Configuration Example of Wake-Up Circuit]
FIG. 9 is a diagram showing a fourth configuration example of the Wake-Up circuit 13 of FIG. In FIG. 9, in the fourth configuration example of the Wake-Up circuit 13, in the third configuration example shown in FIG. As a result, it is smaller, has higher sensitivity, and consumes less power than the conventional type.

(6-1. Configuration example of detection unit)
FIG. 10 is a diagram showing a circuit configuration example of the detection circuit 31 of FIG. The detection circuit 31 includes a resistor R1, an FET1, a capacitor C1, a resistor R2, an FET2, a capacitor C2, a resistor R3, a resistor R4, a capacitor C3, a voltage source VDD, a current source Io, and a diode connection. A bias circuit 40 composed of an FET 3, a switch SW1, and an instrumentation amplifier (instrumentation AMP) 41 are provided.

The control unit 15 causes the detection circuit 31 to intermittently operate according to the Enable Control signal. Specifically, the ON/OFF of SW1 is switched by the Enable Control signal, and the application of the bias voltage of the bias circuit 40 to the gates of FET1 and FET2 is turned ON/OFF to intermittently operate. Further, the control unit 15 causes the instrumentation amplifier 41 to intermittently operate according to the Enable Control signal.

An RF signal is input to the gate of FET1. The gate of FET1 is connected to bias circuit 40 via resistor R3. The source of FET1 is grounded. The drain of the FET1 is connected in parallel with the voltage source VDD through the resistor R1 and the + differential input terminal of the instrumentation amplifier 41 . A capacitor C1 is connected between the drain and source of FET1.

The gate of FET2 is connected in parallel with capacitor C3 and bias circuit 40 via resistor R4. The source of FET2 is grounded. The drain of the FET2 is connected in parallel with the constant voltage source VDD through the resistor R2 and the -differential input terminal of the instrumentation amplifier 41 . A capacitor C2 is connected between the drain and source of FET2.

The instrumentation amplifier 41 inputs the drain voltage of FET1 to the -differential input terminal, the drain voltage of FET2 to the -differential input terminal, and differentially amplifies the differential input of the RF signal. Output to comparator 32 .

The FET1 and FET2 are biased in the sub-threshold region by the bias circuit 40, and the drain currents I _dFET1 and I _dFET2 flowing through the FET1 and FET2 when there is no RF input are given by the following equations.

Here, the drain current _IdFET1 flowing through the FET1 when there is an RF input is given by the following equation.

Since the drain current of FET1 flows with respect to FET2 by the term of the broken line in the above equation, the voltage of NodeA decreases with respect to NodeB, and a difference occurs in the input of the instrumentation amplifier 41. Up signal can be detected.

(6-2. Timing chart of wake-up circuit)
FIG. 11 is a diagram showing an example of a timing chart of the Wake-Up circuit 13 of FIG. 9, (A) is the waveform of Node A in FIG. 9 (input of antenna 11), (B) is the waveform of Node B in FIG. 9 (output of detection circuit 31), and (C) is the waveform of Node C in FIG. (output of the comparator 32). As shown in (A), the RF signal is superimposed on NodeA, and when the voltage of NodeB drops below the reference voltage Vref as shown in (B), NodeC (comparator 32 ) outputs a Wake-Up signal.

In the example shown in FIG. 11, for example, the first pulse of the RF signal (Wake-Up beacon) has a small amplitude due to attenuation or the like, so the Wake-Up signal cannot be detected, but the second pulse of the RF signal The pulse (beacon for Wake-Up) shows a case where the Wake-Up signal can be detected because the amplitude is greater than or equal to a predetermined value.

Here, it is assumed that the reference voltage Vref is lower than the reference voltage Vref, but the present invention is not limited to this. A configuration may be adopted in which a Wake-Up signal is output when the voltage rises.

In the above embodiment, the trifiler transformer 22 is used, but the present invention is not limited to this. Just do it. Moreover, you may use another kind of amplifier instead of LNA21.

Further, in the present embodiment, the Wake-Up beacon is transmitted from the base station 2, but the communication device that transmits the Wake-Up beacon is not limited to this. Other communication devices, such as a smart phone, may transmit.

As described above, according to the present embodiment, the Wake-Up circuit 13 is provided between the antenna 11 and the LNA 21 or on the output side of the LNA 21, functions as a matching circuit, and connects the input side coil and the output side coil. , a trifiler transformer 22 including a detection coil, a detection circuit 14 that detects and outputs a wakeup signal from an RF signal of a wakeup beacon transmitted from another communication device based on the output of the detection coil. , so that the transformer functioning as a matching circuit is provided with the detection coil, so that the size of the Wake-Up circuit can be reduced.

In this case, by providing a trifiler transformer 22 between the antenna 11 and the LNA 21, it is possible to further reduce the size.

Further, by providing the trifiler transformer 22 on the output side of the LNA 21, it is possible to improve the detection sensitivity of the Wake-Up signal.

Further, according to the present embodiment, the detection circuit 14 compares the detection circuit 31 that detects the output of the detection coil P3, the output of the detection circuit 31, and the reference voltage Vref, and outputs the comparison result as Wake- and the comparator 32 that outputs the Up signal, it is possible to detect the Wake-Up signal with a simple configuration.

Also, according to the present invention, the detection circuit 14 and/or the LNA 21 intermittently operate, so power consumption can be reduced.

1 Wireless System 2 Base Station 3 Wireless Device 10 Wireless Module 11 Antenna 12 Transceiver 13 Wake-Up Circuit 14 Detection Circuit 15 Control Unit 16 First LDO
17 Second LDO
20 Battery 21 LNA
22 Trifiler Transformer 23 Balun Transformer 31 Detection Circuit 32 Comparator 40 Bias Circuit 41 Instrumentation Amplifier

Claims (6)

A wake-up circuit for a wireless device that demodulates an RF signal input from an antenna after amplifying the RF signal with an amplifier,
a transformer provided between the antenna and the amplifier or on the output side of the amplifier, functioning as a matching circuit, and having a detection coil for detecting a wakeup signal;
a detection circuit that detects and outputs a wakeup signal from an RF signal of a wakeup beacon transmitted from another communication device based on the output of the detection coil;
A wake-up circuit for a wireless device, comprising: 2. The wireless device wake-up circuit of claim 1, wherein the transformer is a Trifilar Transformer. 3. The wireless device wake-up circuit according to claim 1, wherein the amplifier is an LNA (Low Noise AMP). The detection circuit is
a detection circuit for detecting the output of the detection coil;
a comparator that compares the output of the detection circuit with a reference voltage and outputs the comparison result as the wakeup signal;
The wireless device wake-up circuit according to any one of claims 1 to 3, comprising: The wireless device wake-up circuit according to any one of claims 1 to 4, wherein the detection circuit and/or the amplifier operate intermittently. The wireless device wake-up circuit according to any one of claims 1 to 5, wherein the other communication device is a base station.

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