JP2020202537A - Wake-up circuit of wireless device - Google Patents

Abstract

To provide a wake-up circuit of a wireless device that allows the wake-up circuit of the wireless device using a millimeter wave band to be miniaturized.SOLUTION: A wake-up circuit according to an embodiment is a wake-up circuit of a wireless device that demodulates RF signals after amplifying the RF signals input from an antenna with an amplifier, and includes: a transformer that is provided between the antenna and the amplifier or on an output side of the amplifier, functions as a matching circuit, and includes a detection coil for detecting a wake-up signal; and a detection circuit that detects and outputs a wake-up signal from an RF signal of a wake-up beacon transmitted from another communication device, based on an output of the detection coil.SELECTED DRAWING: Figure 5

Description

The present invention relates to a wake-up circuit for a wireless device.

For example, in order for all things represented by the International Organization of Employers (IoE) to exchange large-scale data with a wireless system, a small and low power consumption wireless system is required. Recently, the development of wireless devices in the 60 GHz band has been actively carried out. The wireless device used in such a wireless system uses a wakeup circuit to activate the main circuit. Therefore, even the wake-up circuit is required to be miniaturized and have low power consumption.

FIG. 12 is a diagram showing an example of a wake-up circuit of a conventional wireless device. For example, conventionally, as shown in FIGS. 12A and 12C, a λ / 4 coupler is provided in the front and rear stages of the LNA, and a wakeup signal is detected by a detection circuit from the output of the λ / 4 coupler. Was. Further, conventionally, as shown in FIG. 12B, for example, the input of the RF signal and the wakeup signal is switched by the switch, and the wakeup signal is detected by the detection circuit from the output of the separately provided LNA. As described above, the conventional wake-up circuit cannot be miniaturized because it uses a λ / 4 coupler, a switch, and an LNA for the input of the detection circuit.

JP-A-2007-258901

The present invention has been made in view of the above, and an object of the present invention is to provide a wake-up circuit of a wireless device capable of miniaturizing a wake-up circuit of a wireless device using a millimeter wave band.

In order to solve the above-mentioned problems and achieve the object, the present invention is a wake-up circuit of a wireless device that amplifies an RF signal input from an antenna with LNA and then demolishes the RF signal. A transformer provided between the amplifiers or on the output side of the amplifier, which functions as a matching circuit and has a detection coil for detecting a wake-up signal, and is transmitted from another communication device based on the output of the detection coil. It is characterized by including a detection circuit that detects and outputs a wakeup signal from the RF signal of the 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 the detection circuit that detects the output of the detection coil with the output of the detection circuit and the reference voltage, and wakes up the comparison result. A comparator that outputs as a signal may be included.

Further, according to one aspect of the present invention, the detection circuit and / or the amplifier may perform intermittent operation.

Further, 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 wake-up circuit of a wireless device that uses the millimeter wave band.

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

Hereinafter, embodiments of a wake-up circuit for a wireless device according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment. In addition, the components in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same. Although the components of the present invention are generally shown in the drawings of the present specification, it is easily understood that the components may be widely arranged and designed in various configurations. Therefore, the following more detailed description of an embodiment of the apparatus of the present invention does not limit the scope of the invention as shown in the claims, but merely shows an example of the selected embodiment of the present invention. is there. The present specification incorporates known techniques by reference. Therefore, those skilled in the art can understand that the present invention can be realized without one or more specific details, or with other methods, parts, and materials by using known techniques.

[1. Wireless system configuration example]
In the wireless system, an Event driven type work-up or the like is used. In the present embodiment, a compact and low power consumption Event driven wakeup circuit using a millimeter wave band is used, and a transformer having a detection coil for detecting the wakeup signal (for example, a Trifilar Transformer) is used. Realize using.

FIG. 1 is a diagram showing an example of a wireless system according to the present embodiment. As shown in FIG. 1, the wireless system 1 according to the present embodiment includes a base station 2 and wireless devices 3 such as smartphones, mobile phone terminals, and tablets. The base station 2 and the wireless device 3 ... Communicate using, for example, a millimeter wave band (for example, a 60 GHz band).

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

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

When the wireless device 3 approaches the base station 2 in the standby state (also referred to as "Wake-Up mode") which is a power saving state, the FR signal of the Wake-Up beacon transmitted from the base station 2 is used. The 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 "reception mode") in which communication is possible.

For example, when the wireless device 3 approaches the base station 2, the wireless device 3 detects the 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. After that, 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 (for example, big data) from the base station 2. In this way, the wireless device 3 can instantly download desired data simply by approaching the base station 2.

[2. Wireless device configuration example]
FIG. 3 is a diagram showing a schematic configuration example of the wireless device 3. The wireless device 3 is roughly classified into a wireless module 10 for performing wireless communication and a battery 20 for supplying electric 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 first unit. It is equipped with two LDOs (linear regulators) 17.

The battery 20 is, for example, a storage battery such as a lithium ion battery, and supplies electric 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 into a predetermined voltage level, and outputs the power to the detection circuit 14.

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

The transceiver 12 is a circuit used for data communication. Since the transceiver 12 is not supplied with power from the second LDO 17 in the standby state, only a passive element such as a trifilar transformer and a circuit 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, power is supplied from the second LDO 17 and the active element operates to enter a normal state in which communication is possible.

The transceiver 12 includes an LNA, a matching circuit equipped with a trifilar transformer, a modulator, a demodulator, a local oscillator, a filter, and the like. The transceiver 12 modulates the transmission data generated by the control unit 15 by a predetermined method to generate a transmission signal (RF signal), and transmits the transmission signal via the antenna 11. Further, the transceiver 12 receives the received signal (RF signal) via the antenna 11, demodulates the received signal by a predetermined method, and outputs the received data obtained by demodulating the received signal to the control unit 15. As the modulation / demodulation method, for example, a superheterodyne method or a direct conversion method can be used.

The Wake-Up circuit 13 includes 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 constantly supplied with electric power from the first LDO 16, the detection circuit 14 operates permanently. Since the trifilar transformer is a passive element, it can operate even when no power is supplied.

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 causes the control unit 15 to detect the Wake-Up signal. Output.

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

The control unit 15 shifts from the normal state to the standby state under predetermined conditions (for example, when the operation of the wireless device 3 is not performed for a predetermined time in an operation unit (not shown)), and the Wake-Up circuit is in the standby state. When the Wake-Up signal is input from 13, the normal state is entered. Specifically, when the Wake-Up signal is input from the Wake-Up circuit 13, the control unit 15 sends a Wake-ON signal to the second LDO 17 and the transceiver 12, and the second LDO 17 and the transceiver 12 To start.

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

When an RF signal as shown in (A) is input from the base station 2, the Wake-Up circuit 13 detects the Wake-Up signal as shown in (B) from the RF signal and outputs it to the control unit 15. To 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 or the transceiver 12. When the Wake-ON signal is input, the transceiver 12 shifts to the normal state and can transmit and receive data as shown in (D).

For example, the control unit 15 may perform various authentication operations with the base station 2 after shifting to the normal state, recognize that it is a desired signal, and then perform data communication (for example, download big data). If the signal is not the desired signal, the wireless device 3 may be moved 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, when the Wake-Up signal is detected by using the trifilar transformer 22 in the matching circuit of the LNA (Low Noise Amplifier) 21 of the antenna 11 and the transceiver 12, the conventional type is used. Achieves miniaturization. As shown in FIG. 5, the detection circuit 14 includes a detection circuit 31 and a comparator 32.

The Wake-Up circuit 13 is provided between the antenna 11 and the LNA 21, functions as an impedance matching circuit between the antenna 11 and the LNA 21, and inputs the RF signal to the input side coil P1 (first winding) and the RF signal to the LNA 21. Detects the output of the output side coil P2 (second winding), the trifilar transformer 22 including the detection coil P3 (third winding) for detecting the Wake-Up signal, and the detection coil P3. The detection circuit 31 is provided with a comparator 32 that compares the output of the detection circuit 31 with the reference voltage Vref and outputs the comparison result as a Wake-Up signal to the control unit 15. As described above, by mounting the matching circuit and the trifilar transformer 22 functioning for the Wake-Up signal detection, the configuration for the Wake-Up signal detection can be miniaturized.

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

Next, the operation of detecting the Wake-Up signal from the RF signal in the standby state will be described. The 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. The detection output and the reference voltage Vref are input to the comparator 32, the reference voltage Vref and the detection output are compared, and the comparison result is output 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 the same functions as those in FIG. 5 are designated by a common reference numeral, and the description of the common parts will be omitted. In FIG. 6, in the second configuration example of the Wake-Up circuit 13, in the first configuration example shown in FIG. 5, the control unit 15 sends an Enable Control signal to the detection circuit 31 to intermittently send the Enable Control signal to the detection circuit 31. By performing the operation, low power consumption is realized.

FIG. 7 is a diagram showing an example of the timing of the intermittent operation. In FIG. 7, as shown in (A), the period of the Wake-Up beacon transmitted from the base station 2 is, for example, a width = 10 μsec and a rest 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 = 110 μsec and a pause period = 1 msec, and it is also a timing at which two Wake-Up beacons can be detected in one operation. Good.

[5. Third configuration example of the 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 trifilar transformer 22 in the subsequent stage of the LNA 21, that is, in the matching circuit of the output of the LNA 21, the size and sensitivity are increased as compared with the conventional type. Has been realized. A matching circuit, the Balun transformer 23, is arranged between the antenna 11 and the LNA 21.

By arranging the trifilar transformer 22 after the LNA 21 in this way, it is possible to detect the Wake-Up signal with high sensitivity. In the third configuration example, power is supplied to the LNA 21 from the second LDO 17 (see FIG. 3) even in the standby state, and the LNA 21 can operate. Since the configuration and operation of the detection circuit 31 and the comparator 32 are the same as those of the first configuration example, the description thereof will be 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. 8, the control unit 15 sends an Enable Control signal to the LNA 21 and the detection circuit 31 to perform intermittent operation. By making it possible, it is smaller, more sensitive, 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, a FET 1, a capacitor C1, a resistor R2, a FET 2, a capacitor C2, a resistor R3, a resistor R4, a capacitor C3, a voltage source VDD, a current source Io, and a diode connection. It includes a bias circuit 40 composed of the above-mentioned FET 3, a switch SW1, and an instrumentation AMP 41.

The control unit 15 intermittently operates the detection circuit 31 by the Enable Control signal. Specifically, the SW1 is switched ON / OFF 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 perform intermittent operation. In addition, the control unit 15 intermittently operates the instrument maintenance amplifier 41 by the Enable Control signal.

An RF signal is input to the gate of FET1. The gate of the FET 1 is connected to the bias circuit 40 via the resistor R3. The source of FET1 is grounded. The drain of the FET 1 is connected in parallel with the voltage source VDD and the + differential input terminal of the instrument maintenance amplifier 41 via the resistor R1. Further, a capacitor C1 is connected between the drain and the source of the FET 1.

In the FET 2, the gate is connected to the capacitor C3 and the bias circuit 40 in parallel via the resistor R4. The source of FET 2 is grounded. In the drain of the FET 2, the constant voltage source VDD via the resistor R2 and the-differential input terminal of the instrument maintenance amplifier 41 are connected in parallel. Further, a capacitor C2 is connected between the drain and the source of the FET 2.

In the instrumentation amplifier 41, the drain voltage of FET1 is input to the-differential input terminal, the drain voltage of FET2 is input to the-differential input terminal, and the differential input of the RF signal is differentially amplified. Output to the comparator 32.

The FET 1 and FET 2 are biased to the sub-threshold region by the bias circuit 40, and the drain currents I _dFET1 and I _{dFET 2} flowing through the FET 1 and the FET 2 when there is no RF input are as shown in the following equation.

Here, the drain current I _dFET1 flowing through the FET 1 when there is an RF input is as shown in the following equation.

Since the drain current of FET1 flows to FET2 only for the term of the broken line in the above equation, the voltage of NodeA drops with respect to NodeB, and a difference occurs in the input of the instrumentation amplifier 41. Therefore, Wake- The Up signal can be detected.

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

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

Here, it is assumed that the voltage is lower than the reference voltage Vref, but the present invention is not limited to this. By adding an inverting amplifier circuit after detection and inverting the characteristics of the comparator 32, the voltage is lower than the reference voltage Vref. The Wake-Up signal may be output when the voltage rises.

In the above embodiment, the trifilar transformer 22 is used, but the present invention is not limited to this, and the transformer (matching circuit) may be configured to include a coil for detecting a Wake-Up signal. Just do it. Further, another type of amplifier may be used instead of the LNA 21.

Further, in the present embodiment, the beacon for Wake-Up is transmitted from the base station 2, but the communication device for transmitting the beacon for Wake-Up is not limited to this, and for example, a personal computer, a tablet, or the like. It may be transmitted by another communication device such as a smartphone.

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 has an input side coil and an output side coil. , The trifilar transformer 22 including the detection coil, and the detection circuit 14 that detects and outputs the wakeup signal from the RF signal of the wakeup beacon transmitted from another communication device based on the output of the detection coil. , Therefore, since the transformer functioning as a matching circuit is provided with the detection coil, the Wake-Up circuit can be miniaturized.

In this case, by providing the trifilar transformer 22 between the antenna 11 and the LNA 21, the size can be further reduced.

Further, by providing the trifilar 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 output of the detection circuit 31 that detects the output of the detection coil P3 with the output of the detection circuit 31 and the reference voltage Vref, and obtains a comparison result of Wake-. Since the comparator 32 that outputs as an Up signal is included, the Wake-Up signal can be detected with a simple configuration.

Further, according to the present invention, since the detection circuit 14 and / or the LNA 21 is determined to perform intermittent operation, it is possible to reduce the power consumption.

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 Trifilar Transformer 23 Balun Transformer 31 Detection Circuit 32 Comparator 40 Bias Circuit 41 Instrumentation Amplifier

Claims (6)

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

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