Optical sensor tag chip and communication method and communication system thereof

Abstract

The application discloses an optical sensor tag chip and a communication method and system thereof, and belongs to the field of communication.The optical sensor tag chip comprises an energy supply system, an analog front end, a digital baseband and a modulation circuit.The energy supply system comprises a full-difference rectifier circuit, a photovoltaic cell charge pump combination circuit and an energy management unit.The full-difference rectifier circuit and the photovoltaic cell charge pump combination circuit are electrically connected with the energy management unit.The analog front end is electrically connected with the energy supply system.The analog front end comprises an optical sensor, which is used for converting an optical signal into an electrical signal and generating a first transmission signal.The digital baseband is electrically connected with the analog front end.The digital baseband is used for encoding and checking the first transmission signal and generating a second transmission signal.The modulation circuit is electrically connected with the digital baseband, used for modulating the second transmission signal and transmitting the second transmission signal to a mobile device, so that the application range of the optical sensor tag chip can be improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of communication, and particularly relates to an optical sensor tag chip and a communication method and system thereof. BACKGROUND

[0002] Generally, the Internet of Things (IoT) technology has been widely applied in intelligent home, smart city, smart agriculture, logistics transportation and biological medicine and other fields after decades of development. The Internet of Things technology mainly includes Radio Frequency Identification (RFID), Bluetooth, WiFi and ZigBee technologies. RFID electronic tags have been gradually applied to the field of identification technology. RFID electronic tags mainly consist of three parts: tag chip, reader, data transmission and processing system. The optical sensor tag chip is a microchip integrating optical sensing function and wireless communication function. It converts the light signal into an electrical signal by sensing the change of light in the environment, and further modulates the electrical signal onto the wireless communication signal to realize data transmission.

[0003] The common optical sensor tag chip currently includes an optical sensor, an oscillator, a memory and a processing system. The oscillator is used to provide a clock signal to ensure that the tag can work normally. The timer is used to time the data transmission and reception. The optical sensor is used to collect the light signal and convert the light signal into an electrical signal. The processing system is used to process the electrical signal to generate a communication signal and output the communication signal to the reader, so that the collection of ambient light and communication can be realized. However, the above-mentioned tag chip is a semi-active chip, and its power supply mode is battery power supply or charging and power supply by using solar energy, which leads to that the tag chip cannot work normally under certain extreme weather conditions, and thus the application range of the tag chip is limited. SUMMARY

[0004] In order to solve the above-mentioned problems in the prior art, the present application provides an optical sensor tag chip and a communication method and system thereof. The technical problem to be solved by the present application is solved by the following technical scheme:

[0005] In a first aspect, the present application provides an optical sensor tag chip, comprising:

[0006] An energy supply system, comprising a full-differential rectifier circuit, a photovoltaic cell charge pump combination circuit and an energy management unit. The full-differential rectifier circuit is used to receive a radio frequency signal and convert the radio frequency signal into direct current energy. The photovoltaic cell charge pump combination circuit is used to collect ambient light and generate an electric current. The full-differential rectifier circuit and the photovoltaic cell charge pump combination circuit are electrically connected with the energy management unit. The energy management unit is used to control the full-differential rectifier circuit and / or the photovoltaic cell charge pump combination circuit to supply power.

[0007] an analog front end electrically connected with the energy supply system, the analog front end comprising a light sensor configured to convert a light signal into an electrical signal and generate a first transmission signal;

[0008] a digital baseband electrically connected with the analog front end, the digital baseband configured to encode and check the first transmission signal and generate a second transmission signal;

[0009] a modulation circuit electrically connected with the digital baseband, the modulation circuit configured to modulate the second transmission signal and transmit the modulated second transmission signal to a mobile device.

[0010] In an embodiment of the present application, the energy supply system further comprises a PMOS tube and a capacitor C1, a source of the PMOS tube is connected with the full differential rectifier circuit, a gate of the PMOS tube is connected with the photovoltaic cell charge pump combination circuit, a drain of the PMOS tube is connected with the capacitor C1, and both the PMOS tube and the capacitor C1 are connected with the energy management unit.

[0011] The energy management unit is configured to control the PMOS tube to be turned on or turned off according to a voltage of the capacitor C1.

[0012] In an embodiment of the present application, the analog front end further comprises a reference circuit, a low dropout linear regulator, and a reset circuit, the energy supply system, the low dropout linear regulator, and the light sensor are electrically connected with the reference circuit, the reference circuit is configured to provide a bias current, a bias voltage, and a reference voltage, the low dropout linear regulator is configured to stabilize a current provided by the energy supply system and generate a power supply voltage, and the reset circuit is configured to generate a reset signal.

[0013] In an embodiment of the present application, a clock module is further included, the clock module is configured to provide a clock signal, the analog front end further comprises a frequency division circuit, the digital baseband, the modulation circuit, and the clock module are electrically connected with the frequency division circuit, and the frequency division circuit is configured to divide the clock signal and transmit the divided clock signal to the digital baseband and the modulation circuit.

[0014] In an embodiment of the present application, the clock module comprises an envelope detection circuit and a demodulation circuit, the envelope detection circuit is configured to acquire and extract a clock signal on a carrier signal, one end of the demodulation circuit is connected with the envelope detection circuit, and the other end of the demodulation circuit is connected with the frequency division circuit.

[0015] In an embodiment of the present application, the light sensor comprises a photodiode, a nonlinear current amplifier, a transimpedance amplifier, and a successive approximation register analog-to-digital converter connected in sequence, the photodiode is configured to collect ambient light and convert the ambient light into an electrical signal, the nonlinear current amplifier is configured to amplify the electrical signal output by the photodiode, the transimpedance amplifier is configured to convert a current signal output by the nonlinear current amplifier into a voltage signal, and the successive approximation register analog-to-digital converter is configured to convert the voltage signal output by the transimpedance amplifier into a digital signal and output the digital signal to the digital baseband.

[0016] In one embodiment of the present application, the digital baseband includes an encoding module, a process management module, a check module and an output control module, the encoding module is connected with the light sensor, the encoding module, the check module and the output control module are all connected with the process management module, the encoding module, the check module and the output control module are connected in sequence, and the output control module is connected with the modulation circuit.

[0017] The encoding module is used for encoding the first transmission signal output by the light sensor, the check module is used for generating a data check code, the output control module is used for transmitting a read / write enable signal and an address signal to the modulation circuit, and the process management module is used for controlling the encoding module, the check module and the output control module to work.

[0018] In one embodiment of the present application, the modulation circuit is an FSK circuit and an MN1 tube, the frequency division circuit and the output control module are both connected with the FSK circuit, the frequency division circuit outputs two clock signals with different frequencies to the FSK circuit, the FSK circuit is used for modulating the signal transmitted by the output control module according to the two clock signals with different frequencies output by the frequency division circuit, and the MN1 tube is used for backscatter modulation of the signal output by the FSK circuit to obtain a modulation wave of the BLE communication channel.

[0019] In a second aspect, the present application provides a communication method of a light sensor tag chip, applied to the light sensor tag chip provided in the above-mentioned solution, the light sensor tag chip including an energy supply system, the energy supply system including a full-differential rectifier circuit, a photovoltaic cell charge pump combination circuit and an energy management unit, and the method includes:

[0020] When the light sensor tag chip is in a first brightness environment, the energy management unit controls the photovoltaic cell charge pump combination circuit to supply power;

[0021] When the light sensor tag chip is in a second brightness environment, the energy management unit controls the full-differential rectifier circuit to supply power;

[0022] Among them, the brightness value of the first brightness environment is greater than a preset brightness threshold value, and the brightness value of the second brightness environment is less than the preset brightness threshold value.

[0023] In a third aspect, the present application provides a communication system, applied to BLE passive backscatter communication, including a carrier transmitter, a 2.4GHz transmitter, a mobile device and a light sensor tag chip provided in the above-mentioned solution, the carrier transmitter is used for sending a carrier signal to the energy supply system of the light sensor tag chip, the 2.4GHz transmitter is used for sending a 2.4GHz carrier to the modulation circuit of the light sensor tag chip, and the light sensor tag chip is used for collecting ambient light to generate a communication signal and transmitting the communication signal to the mobile device.

[0024] Compared with the prior art, the application has the following beneficial effects:

[0025] In the above scheme of the application, the optical sensor tag chip comprises an energy supply system, an analog front end, a digital baseband and a modulation circuit. The energy supply system comprises a full-difference rectifier circuit, a photovoltaic cell charge pump combination circuit and an energy management unit. The full-difference rectifier circuit is used to receive a radio frequency signal and convert the radio frequency signal into direct current energy. The photovoltaic cell charge pump combination circuit is used to collect ambient light and generate an electric current. The full-difference rectifier circuit and the photovoltaic cell charge pump combination circuit are both electrically connected to the energy management unit. The energy management unit is used to control the full-difference rectifier circuit and / or the photovoltaic cell charge pump combination circuit to supply power. The analog front end is electrically connected to the energy supply system. The analog front end comprises an optical sensor. The optical sensor is used to convert a light signal into an electric signal and generate a first transmission signal. The digital baseband is electrically connected to the analog front end. The digital baseband is used to perform encoding and checking processing on the first transmission signal and generate a second transmission signal. The modulation circuit is electrically connected to the digital baseband. The modulation circuit is used to modulate the second transmission signal and transmit the second transmission signal to a mobile device. In this way, the optical sensor tag chip can realize the collection of ambient light and communication. By using this structure, first, the full-difference rectifier circuit receives a radio frequency signal and converts the radio frequency signal into direct current energy. The photovoltaic cell charge pump combination circuit collects ambient light and generates an electric current. The optical sensor tag chip can use ambient light energy to supply power and can use a radio frequency signal to supply power. Therefore, different power supply modes can be used according to different use environments. The optical sensor tag chip can be suitable for various extreme weather conditions and the application range of the optical sensor tag chip is improved. In addition, the optical sensor tag chip described above can use a three-point communication system architecture to separate the energy collection and communication functions, thereby optimizing the communication distance of the optical sensor tag chip. Moreover, each circuit module in the optical sensor tag chip described above can be integrated inside the chip, so that the integration degree of the optical sensor tag chip is higher.

[0026] The application will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 FIG. 1 is a schematic diagram of an optical sensor tag chip provided by an embodiment of the application;

[0028] Figure 2 FIG. 1 is a schematic diagram of an optical sensor tag chip provided by an embodiment of the application;

[0029] Figure 3 FIG. 1 is a schematic diagram of an optical sensor tag chip provided by an embodiment of the application;

[0030] Figure 4 FIG. 1 is a schematic diagram of an optical sensor tag chip provided by an embodiment of the application;

[0031] Figure 5 is a schematic diagram of a working process of a digital baseband in an embodiment of the present application;

[0032] Figure 6 is a schematic diagram of a communication system provided by an embodiment of the present application. DETAILED DESCRIPTION

[0033] The present application will be further described in details below in conjunction with specific embodiments, but the embodiments of the present application are not limited thereto.

[0034] Internet of Things (IoT) technology has been widely applied in smart home, smart city, smart agriculture, logistics and transportation, and biological medicine after decades of development. Internet of Things technology mainly includes Radio Frequency Identification (RFID), Bluetooth, WiFi and ZigBee technologies, among which the radio frequency identification technology is the most mature technology, with the advantages of low cost, long life, and reusable, and is widely used in logistics, management, production, transportation and other fields.

[0035] Bluetooth Low Energy (BLE) is a personal area network technology designed by Bluetooth Special Interest Group, which can be applied in enterprise Internet of Things, beacon, smart home appliances, device management and other fields. Compared with classic Bluetooth, low-power Bluetooth aims to significantly reduce power consumption and cost while maintaining the same communication range. With the popularity of portable mobile devices, today's smartphones and mobile devices have widely applied low-power Bluetooth standards, which makes every mobile device become a potential reader. However, the power consumption of the traditional BLE transmitter is still too large compared with the power consumption of backscatter modulation. If the uplink information path of the traditional passive tag is changed, the data is transmitted to the mobile device through the low-power Bluetooth channel by using backscatter technology, not only can realize long-distance mobile communication, but also the energy consumption of backscatter is far less than the energy consumption of the traditional BLE transmitter.

[0036] Wireless sensor network (WSN) is an important part of the development of the Internet of Things. In these practical applications, the collection of sensor information is crucial, and a sensor system without information collection has no practical significance. Therefore, the collection and quantification of a variable in the environment by an Internet of Things node or tag is one of the cores of a wireless sensor network. An ambient light sensor generally consists of a photosensitive element and a data conversion module. The ambient light sensor can convert illumination into an electrical signal to achieve the functions of controlling backlight brightness and improving user visual effects. The common traditional light sensor has the disadvantages of large size, high power consumption, high cost, etc., and cannot be well applied to the Internet of Things. The integrated light sensor tag chip has the advantages of small size, low power consumption, wide application range, low cost, high reliability, etc. The application of the integrated light sensor tag chip in smart home, environmental monitoring, intelligent agriculture, etc. can passively collect and quantify ambient light and communicate with mobile devices.

[0037] Embodiment one:

[0038] Please refer to Figure 1 , Figure 2 , Figure 3 and Figure 6 , the embodiment of the present application provides a light sensor tag chip, which comprises an energy supply system, an analog front end, a digital baseband and a modulation circuit. The energy supply system comprises a full-differential rectifier circuit, a photovoltaic cell charge pump combination circuit and an energy management unit. The full-differential rectifier circuit is used for receiving a radio frequency signal and converting the radio frequency signal into direct current energy. The photovoltaic cell charge pump combination circuit is used for collecting ambient light and generating a current. The full-differential rectifier circuit and the photovoltaic cell charge pump combination circuit are both electrically connected with the energy management unit. The energy management unit is used for controlling the full-differential rectifier circuit and / or the photovoltaic cell charge pump combination circuit to supply power. The analog front end is electrically connected with the energy supply system. The analog front end comprises a light sensor. The light sensor is used for converting a light signal into an electrical signal and generating a first transmission signal. The digital baseband is electrically connected with the analog front end. The digital baseband is used for encoding and checking processing the first transmission signal and generating a second transmission signal. The modulation circuit is electrically connected with the digital baseband. The modulation circuit is used for modulating the second transmission signal and transmitting the second transmission signal to a mobile device.

[0039] In some embodiments of the present application, the full-differential rectifier circuit (RECT, Rectifier) is a circuit structure for converting alternating current into direct current. A common full-differential rectifier circuit is composed of two differential input rectifiers, and the rectifier can be a diode. In the embodiment of the present application, the full-differential rectifier circuit RECT can convert the alternating current signal received by the antenna into a direct current signal.

[0040] In some embodiments of the present application, the full-differential rectifier circuit RECT is a five-stage rectifier.

[0041] In some embodiments of the present application, the photocell charge pump combination circuit (Photocell CP) is a circuit that combines photocell and charge pump technology, used to convert light energy into electrical energy and perform voltage regulation or voltage boosting.

[0042] In some embodiments of the present application, as shown in Figure 2 and Figure 3 , the photocell charge pump combination circuit Photocell CP includes a photocell group and a three-stage cascade charge pump, the photocell group is composed of on-chip photodiodes in parallel, all negative electrodes of the photodiodes are grounded, and the positive electrodes are output as light energy collection output terminals to the three-stage cascade charge pump. Since the voltage of a conventional single-junction photocell is less than 0.5V, a series of PN junctions is used for voltage boosting. Using a standard CMOS process, taking a P+ / NWELL type PN junction as an example, the first stage structure is consistent with a single-stage photodiode, NWEL is connected to PSUB through a metal short circuit and is led out as the negative electrode of the entire photocell, the P terminal is connected to the second-stage NWELL through a metal connection, completing the series connection of the two-stage photocell, and the second-stage P terminal is led out as the positive electrode of the entire photocell. As can be seen from the circuit model diagram of Figure 3 , the parasitic transistor of the first stage is shielded by short circuiting.

[0043] In some embodiments of the present application, the power management unit (PMU) is a highly integrated microcontroller mainly used for controlling the power supply function of a digital platform. The power management unit PMU integrates traditional discrete power management devices (such as low dropout linear regulator (LDO), direct current converter (DC / DC), etc.) in a single package to achieve higher power conversion efficiency, lower power consumption and fewer component quantities, and adapt to the reduced board space.

[0044] In some embodiments of the present application, the light sensor tag chip is a passive micro-power light sensor tag chip.

[0045] In some embodiments of the present application, the light sensor tag chip of the present application is used in a passive BLE backscatter communication system. The BLE backscatter communication system is a system that uses Bluetooth Low Energy (BLE) technology to achieve wireless communication, and its core is to transmit data by reflecting or scattering the incident BLE signal without actively transmitting radio frequency signals. This technology is similar to the principle of radar, part of the electromagnetic wave energy is reflected when it encounters an object, and the strength of the reflected signal depends on the shape, material and distance of the object. By changing the strength of the reflected signal, data transmission can be achieved.

[0046] In some embodiments of the present application, when the light sensor tag chip is in an environment with high light intensity, the photocell group outputs a photovoltaic voltage at the positive electrode, but this voltage is still insufficient to make the subsequent circuit work normally. To solve this problem, a charge pump needs to be used at the photovoltaic voltage output end to perform voltage boosting processing again. When the light sensor tag chip is in an environment with weak light intensity, the voltage output by the charge pump can be considered to be low, at which time the energy management unit is switched to a full differential rectifier circuit to use radio frequency energy for power supply.

[0047] In some embodiments of the present application, the light sensor is a device capable of converting light energy into an electrical signal, mainly used for detecting light energy in the range from ultraviolet light to infrared light. The light sensor is mainly composed of a photosensitive element and can be divided into ambient light sensors, infrared light sensors, sunlight sensors, ultraviolet light sensors and other types. The light sensor in the embodiments of the present application is an ambient light sensor (ALS).

[0048] In some embodiments of the present application, the light sensor tag chip of the present application has low power consumption and is highly integrated, does not need to be provided with an external power supply voltage, can be applied to various ambient light detection scenes, and can communicate with a mobile device at a long distance. After the ambient light is collected, quantized and modulated, the data can be transmitted to the mobile device in a backscattering manner.

[0049] In some embodiments of the present application, the mobile device can be a mobile electronic device such as a mobile phone, a tablet computer or a remote controller.

[0050] In the above scheme of the application, the optical sensor tag chip comprises an energy supply system, an analog front end, a digital baseband and a modulation circuit. The energy supply system comprises a full differential rectifier circuit, a photovoltaic cell charge pump combination circuit and an energy management unit. The full differential rectifier circuit is used to receive a radio frequency signal and convert the radio frequency signal into direct current energy. The photovoltaic cell charge pump combination circuit is used to collect ambient light and generate a current. The full differential rectifier circuit and the photovoltaic cell charge pump combination circuit are both electrically connected to the energy management unit. The energy management unit is used to control the full differential rectifier circuit and / or the photovoltaic cell charge pump combination circuit to supply power. The analog front end is electrically connected to the energy supply system. The analog front end comprises an optical sensor. The optical sensor is used to convert an optical signal into an electrical signal and generate a first transmission signal. The digital baseband is electrically connected to the analog front end. The digital baseband is used to perform encoding and checking processing on the first transmission signal and generate a second transmission signal. The modulation circuit is electrically connected to the digital baseband. The modulation circuit is used to modulate the second transmission signal and transmit the second transmission signal to a mobile device. In this way, the optical sensor tag chip can realize the collection of ambient light and communication. With this structure, first, the full differential rectifier circuit receives a radio frequency signal and converts the radio frequency signal into direct current energy. The photovoltaic cell charge pump combination circuit collects ambient light and generates a current. The optical sensor tag chip can use ambient light energy for power supply and can use a radio frequency signal for power supply. Therefore, different power supply modes can be used according to different use environments. The optical sensor tag chip can be suitable for various extreme weather conditions and improve the application range of the optical sensor tag chip. In addition, the optical sensor tag chip can use a three-point communication system architecture to separate the energy collection and communication functions, thereby optimizing the communication distance of the optical sensor tag chip. Moreover, each circuit module in the optical sensor tag chip can be integrated inside the chip, so that the integration degree of the optical sensor tag chip is higher.

[0051] In some embodiments of the application, as shown in Figure 2 The energy supply system further comprises a PMOS tube and a capacitor C1. The source of the PMOS tube is connected to the full differential rectifier circuit. The gate of the PMOS tube is connected to the photovoltaic cell charge pump combination circuit. The drain of the PMOS tube is connected to the capacitor C1 and both are connected to the energy management unit. The energy management unit is used to control the PMOS tube to be turned on or turned off according to the voltage of the capacitor C1. The output of the energy management unit is the energy supply port of the entire tag chip. With this structure, the capacitor C1 can store the energy output by the photovoltaic cell charge pump combination circuit and the full differential rectifier circuit. The energy management unit PMU can control the photovoltaic cell charge pump combination circuit or the full differential rectifier circuit to supply power according to the voltage of the capacitor C1. In addition, when the ambient light is weak, the dual power supply system switches back to radio frequency energy supply. At the same time, a part of energy will be stored on the capacitor C1, so that the energy management unit PMU can be charged to the start voltage faster when switching to radio frequency power supply.

[0052] In some embodiments of the present application, as shown in Figure 2 When the ambient light is weak, the combination of the photovoltaic cell and the charge pump is difficult to reach the voltage required for the normal operation of the subsequent circuit, at this time the MP1 transistor in the energy supply system is turned on, the rectifier circuit collects energy from the radio frequency field and transmits it to the capacitor C1 and the energy management unit PMU, the working mode of the energy management unit PMU is the duty cycle mode; when the voltage on the capacitor C1 reaches a certain value, the energy management unit PMU is turned on, and the whole chip is in working state, and the energy supply system supplies power to the subsequent circuit; when the charge amount of the capacitor C1 is consumed to a certain extent, the voltage drops and is insufficient to continue the work of the subsequent circuit, the energy management unit PMU is turned off, and the chip is in standby state, at this time no energy is consumed, and the rectifier or the charge pump continues to charge the capacitor C1 until the next work can be started.

[0053] In some embodiments of the present application, as shown in Figure 1 The analog front end further includes a reference circuit, a low dropout linear regulator, and a reset circuit, the energy supply system, the low dropout linear regulator, and the light sensor are electrically connected with the reference circuit, the reference circuit is used to provide bias current, bias voltage, and reference voltage, the low dropout linear regulator is used to stabilize the current provided by the energy supply system and generate a power voltage VDD, and the reset circuit is used to generate a reset signal. With this structure, the reference circuit can be used to provide bias current and bias voltage for each module, so that each module can work normally, the reference circuit can provide reference voltage for the low dropout linear regulator, so that the low dropout linear regulator can stabilize the reference voltage and generate the power voltage VDD, which can be used to power each module of the analog front end and the digital baseband, and the reset circuit can generate a voltage jump signal as a reset switch, the reset signal is later than the power voltage VDD at the beginning of work, and the digital baseband starts to work normally after receiving the reset signal, so as to ensure that the light sensor tag chip can work normally.

[0054] In some embodiments of the present application, the reference circuit (REF, Reference) is a kind of existing circuit for providing stable voltage or current reference, which is widely used in various electronic devices to ensure the stability and accuracy of the system.

[0055] In some embodiments of the present application, the low dropout linear regulator (Low Dropout Regulator, LDO) is a kind of existing voltage stabilizer that can keep the output voltage stable, and its core advantage is that it can keep the output voltage stable when the pressure difference between the input voltage and the output voltage is small.

[0056] In some embodiments of the present application, the bias voltage required by the ambient light sensor, the reference voltage required by the low dropout linear regulator LDO, and the bias current required by each module can be obtained by the reference circuit REF, and the low dropout linear regulator LDO amplifies and stabilizes the reference voltage to provide a power supply voltage VDD for the entire analog front end and digital baseband.

[0057] In some embodiments of the present application, the reset circuit (RST, Reset) is a circuit structure that is used to restore the circuit to the initial state, and is usually composed of a resistor and a capacitor.

[0058] In some embodiments of the present application, the light sensor tag chip further comprises a clock module for providing a clock signal, and the analog front end further comprises a frequency division circuit, and the digital baseband, the modulation circuit, and the clock module are electrically connected to the frequency division circuit, and the frequency division circuit is used to divide the clock signal and transmit the clock signal to the digital baseband and the modulation circuit. With this structure, the clock module provides a clock signal for the analog front end, so that the light sensor tag chip can work normally; when the frequency division circuit divides the clock signal and transmits the clock signal to the digital baseband and the modulation circuit, it can not only ensure that the clock signal can be transmitted to the digital baseband to ensure that the digital baseband can work normally, but also enable the modulation circuit to use two different frequency clock signals for modulation work. Moreover, since the traditional tag on-chip clock is difficult to meet the standard of the BLE backscatter system due to PVT influence, the external clock acquisition method is adopted in this embodiment to obtain the clock signal by the clock module and provide it to the analog front end for further processing, thereby meeting the standard of the BLE backscatter system.

[0059] In some embodiments of the present application, the frequency division circuit can provide the clock signal output by the clock module to the digital baseband as a clock signal CLK, and at the same time, the frequency division circuit can divide the clock signal output by the clock module to obtain two signals F_0 and F_1 of different frequencies, which are used for the modulation circuit.

[0060] In some embodiments of the present application, the clock module comprises an envelope detection circuit and a demodulation circuit, the envelope detection circuit is used to obtain and extract the clock signal on the carrier signal, and one end of the demodulation circuit is connected to the envelope detection circuit, and the other end is connected to the frequency division circuit. With this structure, the clock module can obtain the clock on the carrier signal by envelope detection method. The clock signal on the carrier is extracted by the envelope detection circuit, and the residual carrier frequency is removed by a low-pass filter to obtain a preliminary clock envelope signal. The clock envelope signal and the reference voltage output by the peak holding circuit are restored to the required clock signal through a hysteresis comparator.

[0061] In some embodiments of the present application, the envelope detection circuit (ED) is a kind of existing circuit for extracting the modulated signal from the modulated signal. The envelope detection circuit realizes the demodulation of the amplitude modulation signal through the rectification and filtering process.

[0062] In some embodiments of the present application, the demodulation circuit (DEM) is a kind of existing circuit for restoring the modulated signal to the original signal.

[0063] In some embodiments of the present application, as shown in Figure 4 The light sensor includes a photodiode, a nonlinear current amplifier, a transimpedance amplifier (RTIA) and a successive approximation register analog-to-digital converter (SAR ADC) connected in sequence. The photodiode is used to collect ambient light and convert it into an electrical signal. The nonlinear current amplifier is used to amplify the electrical signal output by the photodiode. The transimpedance amplifier is used to convert the current signal output by the nonlinear current amplifier into a voltage signal. The successive approximation register analog-to-digital converter is used to convert the voltage signal output by the transimpedance amplifier into a digital signal and output it to the digital baseband. With this structure, the photodiode works in the photoconductive mode and is used to convert ambient light intensity into photocurrent. Since the human eye responds to light intensity in a nonlinear range, a nonlinear current amplifier is used to nonlinearly fit and amplify the photocurrent output by the photodiode. The transimpedance amplifier is used to convert the processed photocurrent into a photovoltage signal output. The obtained photovoltage signal is quantized by the successive approximation register analog-to-digital converter and output to the digital baseband. Since the photodiode needs to work under reverse bias voltage, a bias voltage Vbias is applied to the negative electrode of the photodiode. This voltage can be provided by a reference circuit.

[0064] In some embodiments of the present application, the ambient light sensor quantizes the ambient light when the power supply voltage VDD is stable. The specific steps are as follows: the photodiode is under reverse bias due to Vbias, which converts the light intensity received by the light sensor tag chip into photocurrent Iin. In order to handle a wider range of light intensity response, a nonlinear current amplifier is used to convert the current into an amount of current proportional to √Iin, i.e. Iout. The output end of the nonlinear current amplifier is connected to the negative input end of the transimpedance amplifier, and the feedback resistor Rf is connected between the positive input end and the output end of the transimpedance amplifier, which is used to convert the current Iout into a photovoltage. Then the 10-bit successive approximation register analog-to-digital converter SAR ADC quantizes the photovoltage and outputs a 10-bit digital code Data[9:0].

[0065] In some embodiments of the present application, the digital baseband comprises an encoding module (ENCODE), a process management module (PMU), a check module (CRC) and an output control module (OCU), the encoding module is connected with the light sensor, the encoding module, the check module and the output control module are all connected with the process management module, the encoding module, the check module and the output control module are connected in sequence, and the output control module is connected with the modulation circuit; the encoding module is used for encoding the first transmission signal output by the light sensor, the check module is used for generating a data check code, the output control module is used for transmitting a read / write enable signal (Ble_en) and an address signal (Ble_data) to the modulation circuit, and the process management module is used for controlling the encoding module, the check module and the output control module to work. With this structure, the signal output by the analog front end can be encoded and checked by the digital baseband, and the communication data and the related enable signal can be transmitted to the modulation circuit.

[0066] In some embodiments of the present application, the digital baseband can process the tag ID and the data sent by the analog front end into the data format specified by the BLE communication protocol. The encoding module ENCODE is used for encoding the 10-bit data quantized by the ambient light sensor; the check module CRC is used for generating a data check code, and the mobile device can judge whether the data is correct according to the check code; the output control module OCU is used for transmitting the related read / write enable signal (Ble_en) and the address signal (Ble_data) to the modulation circuit; and the process management module PMU is used for controlling the working process of each module.

[0067] In some embodiments of the present application, as shown in Figure 5 The light sensor ALS quantizes the ambient light once, and sends the data Data[9:0] to the digital baseband, and the working process of the digital baseband is shown in Figure 5 When the tag enters the BLE working mode, the process management unit module starts to work, first reads the BLE configuration data and ID data, and manages the data flow processing process by controlling the clock of each module. After the data is encoded and encrypted, the CRC check code is generated by the CRC module, and then the data and the check code are whitened to obtain the data after the whitening process. Next, the preamble, address, quantized data and CRC check code are combined in sequence by the framing module, and then output in series, and the enable signal Ble_en is generated.

[0068] In some embodiments of the present application, the modulation circuit is an FSK circuit and an MN1 transistor, the frequency division circuit and the output control module are connected to the FSK circuit, the frequency division circuit outputs two clock signals of different frequencies to the FSK circuit, the FSK circuit is used for modulating the signal transmitted by the output control module according to the two clock signals of different frequencies output by the frequency division circuit, and the MN1 transistor is used for backscatter modulation of the signal output by the FSK circuit to obtain a modulated wave of the BLE communication channel. With this structure, the modulation circuit can perform FSK modulation on the data and ID processed by the digital baseband, and then backscatter the data and ID to the mobile device through the 2.4GHz carrier.

[0069] In some embodiments of the present application, the FSK circuit is a circuit using frequency shift keying (FSK) technology. FSK is a digital modulation technique that transmits digital information by changing the frequency of a carrier signal. In FSK, two different frequencies are usually used to represent digital 0 and 1. When transmitting a digital 1, the frequency of the carrier is switched to a specific value; when transmitting a digital 0, the frequency of the carrier is switched to another specific value. The receiving end determines whether 0 or 1 is transmitted according to the received signal frequency, thereby recovering the original digital information. The FSK circuit usually includes a carrier generator, a modulator, and a demodulator.

[0070] In some embodiments of the present application, the MN1 transistor is an N-type metal oxide semiconductor (MOS) transistor, the gate of which is connected to the FSK circuit, the source is grounded, and the drain receives the 2.4GHz carrier.

[0071] In some embodiments of the present application, the modulation circuit starts FSK modulation on the data after receiving the enable signal. The clock required for FSK modulation is generated by a frequency divider in the analog front end, and the modulated signal is further backscatter modulated by the MN1 transistor. Finally, the modulated wave of the BLE communication channel is reflected. The modulated wave can be received by the mobile device to read the address data and the light intensity quantized data of the tag.

[0072] Embodiment two:

[0073] The embodiment provides a communication method of a light sensor tag chip, applied to the light sensor tag chip provided in the above-mentioned embodiment one, the light sensor tag chip comprising an energy supply system, the energy supply system comprising a full-differential rectifier circuit, a photovoltaic cell charge pump combination circuit and an energy management unit, and the method comprises the following steps:

[0074] When the light sensor tag chip is in a first brightness environment, the energy management unit controls the photovoltaic cell charge pump combination circuit to supply power;

[0075] When the light sensor tag chip is in the second brightness environment, the energy management unit controls the full differential rectifier circuit to supply power;

[0076] The brightness value of the first brightness environment is greater than a preset brightness threshold value, and the brightness value of the second brightness environment is less than the preset brightness threshold value.

[0077] The beneficial effects of the second embodiment and various implementation manners of the present application can be referred to the beneficial effect analysis in the first embodiment and various implementation manners, which will not be repeated here.

[0078] Embodiment three:

[0079] Please refer to Figure 6 The embodiment provides a communication system applied to BLE passive backscatter communication, including a carrier transmitter, a 2.4GHz transmitter, a mobile device and a light sensor tag chip as provided in the above-mentioned first embodiment, the carrier transmitter is used for transmitting a carrier signal to the energy supply system of the light sensor tag chip, the 2.4GHz transmitter is used for transmitting a 2.4GHz carrier to the modulation circuit of the light sensor tag chip, and the light sensor tag chip is used for collecting ambient light to generate a communication signal and transmitting the communication signal to the mobile device.

[0080] In some embodiments of the present application, the carrier transmitter transmits a 922.5MHz carrier, which includes a 2M clock signal for the ASK circuit. The transmitted carrier is used to provide energy and an external clock for the tag chip. The tag can rectify the carrier energy through the corresponding antenna, thereby providing energy for the chip. At the same time, the clock acquisition module in the tag extracts the envelope in the high-frequency carrier through envelope detection. The extracted envelope signal usually contains some high-frequency components or noise, which needs to be filtered through a band-pass filter. The low-frequency signal after filtering generates a reference voltage through the peak detection circuit, and finally the low-frequency signal is compared with the reference voltage through the hysteresis comparator, and the 2M clock is recovered and output.

[0081] In some embodiments of the present application, the carrier transmitter transmits a 922.5MHz carrier signal to provide the energy required for the passive operation of the tag, and the photovoltaic cell group in the tag chip can also collect ambient light energy to convert it into electrical energy to power the chip.

[0082] In some embodiments of the present application, the 2.4GHz transmitter is used to transmit a 2.4GHz carrier to the modulation circuit, the tag modulates the 2.4GHz carrier, reflects it as a Bluetooth signal meeting the BLE communication standard, and finally uses a mobile device to receive the signal.

[0083] The beneficial effects of the second embodiment and various implementation manners of the present application can be referred to the beneficial effect analysis in the first embodiment and various implementation manners, which will not be repeated here.

[0084] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate different embodiments or examples described in the specification.

[0085] Although the present application is described herein in conjunction with various embodiments, those skilled in the art will appreciate that other changes in the described embodiments can be understood and effected by those skilled in the art in view of the above description, the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions of the described embodiments. Measures described in mutually different dependent claims can be combined and implemented in a combination that is also good.

[0086] Those skilled in the art will appreciate that embodiments of the present application can be provided as methods, apparatuses (devices), or computer program products. Therefore, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects, all of which are referred to herein as "modules" or "systems". Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The computer program can be stored / distributed in a suitable medium, provided with other hardware, or as part of the hardware, and can also take other distribution forms, such as through the Internet or other wired or wireless telecommunications systems.

[0087] The above is a further detailed description of the present application in conjunction with specific preferred embodiments, and the specific implementation of the present application cannot be limited to these descriptions. For those skilled in the art, without departing from the concept of the present application, a number of simple deductions or substitutions can also be made, which should be considered to fall within the scope of protection of the present application.

Claims

1. An optical sensor tag chip, characterized by The energy supply system comprises a full differential rectifier circuit, a photovoltaic cell charge pump combination circuit and an energy management unit, the full differential rectifier circuit is used for receiving a radio frequency signal and converting the radio frequency signal into direct current energy, the photovoltaic cell charge pump combination circuit is used for collecting ambient light and generating an electric current, the full differential rectifier circuit and the photovoltaic cell charge pump combination circuit are electrically connected with the energy management unit, and the energy management unit is used for controlling the full differential rectifier circuit and / or the photovoltaic cell charge pump combination circuit to supply power, wherein the photovoltaic cell charge pump combination circuit comprises a photovoltaic cell group and a three-stage cascade charge pump, the photovoltaic cell group is composed of on-chip photodiodes in parallel, all the negative electrodes of the photodiodes are grounded, and the positive electrodes are output to the three-stage cascade charge pump as a light energy collection output end; An analog front end is electrically connected with the energy supply system, the analog front end comprises a light sensor, and the light sensor is used for converting a light signal into an electric signal and generating a first transmission signal; A digital baseband is electrically connected with the analog front end, and the digital baseband is used for encoding and checking the first transmission signal and generating a second transmission signal; A modulation circuit is electrically connected with the digital baseband, and the modulation circuit is used for modulating the second transmission signal and transmitting the second transmission signal to a mobile device; The energy supply system further comprises a PMOS tube and a capacitor C1, the source of the PMOS tube is connected with the full differential rectifier circuit, the gate of the PMOS tube is connected with the photovoltaic cell charge pump combination circuit, the drain of the PMOS tube is connected with the capacitor C1, and both the PMOS tube and the capacitor C1 are connected with the energy management unit; The energy management unit is used for controlling the PMOS tube to be turned on or turned off according to the voltage of the capacitor C1; The light sensor tag chip further comprises a clock module, the clock module is used for providing a clock signal, the analog front end further comprises a frequency division circuit, the digital baseband, the modulation circuit and the clock module are electrically connected with the frequency division circuit, and the digital baseband comprises an encoding module, a process management module, a checking module and an output control module; The modulation circuit is an FSK circuit and an MN1 tube, the frequency division circuit and the output control module are connected with the FSK circuit, the frequency division circuit outputs two clock signals with different frequencies to the FSK circuit, the FSK circuit is used for modulating the signal transmitted by the output control module according to the two clock signals with different frequencies output by the frequency division circuit, the MN1 tube is used for backscatter modulation of the signal output by the FSK circuit to obtain a modulation wave of a BLE communication channel, the MN1 tube is an N-type metal oxide semiconductor transistor, the gate of the MN1 tube is connected with the FSK circuit, the source is grounded, and the drain receives a 2.4 GHz carrier wave. ​ 2. The optical sensor tag chip according to claim 1, characterized in that The analog front end further comprises a reference circuit, a low-dropout linear regulator and a reset circuit, the energy supply system, the low-dropout linear regulator and the light sensor are electrically connected with the reference circuit, the reference circuit is used for providing bias current, bias voltage and reference voltage, the low-dropout linear regulator is used for stabilizing the current provided by the energy supply system and generating a power supply voltage, and the reset circuit is used for generating a reset signal.

3. The optical sensor tag chip of claim 2, wherein, The frequency division circuit is used for frequency dividing the clock signal and transmitting the clock signal to the digital baseband and the modulation circuit.

4. The optical sensor tag chip of claim 3, wherein, The clock module comprises an envelope detection circuit and a demodulation circuit, the envelope detection circuit is used for acquiring and extracting the clock signal on the carrier signal, one end of the demodulation circuit is connected with the envelope detection circuit, and the other end is connected with the frequency division circuit.

5. The optical sensor tag chip of claim 1, wherein, The light sensor comprises a photodiode, a nonlinear current amplifier, a transimpedance amplifier and a successive approximation analog-to-digital converter connected in sequence, the photodiode is used for collecting ambient light and converting it into an electric signal, the nonlinear current amplifier is used for amplifying the electric signal output by the photodiode, the transimpedance amplifier is used for converting the current signal output by the nonlinear current amplifier into a voltage signal, and the successive approximation analog-to-digital converter is used for converting the voltage signal output by the transimpedance amplifier into a digital signal and outputting the digital signal to the digital baseband.

6. The optical sensor tag chip of claim 4, wherein, The encoding module is connected with the light sensor, the encoding module, the check module and the output control module are connected with the process management module, the encoding module, the check module and the output control module are connected in sequence, and the output control module is connected with the modulation circuit. The encoding module is used for encoding the first transmission signal output by the light sensor, the check module is used for generating a data check code, the output control module is used for transmitting a read / write enable signal and an address signal to the modulation circuit, and the process management module is used for controlling the encoding module, the check module and the output control module to work.

7. A communication method of an optical sensor tag chip, characterized by, The method is applied to the light sensor tag chip in any one of claims 1-6, the light sensor tag chip comprises an energy supply system, the energy supply system comprises a full-differential rectifier circuit, a photovoltaic cell charge pump combination circuit and an energy management unit, and the method comprises: When the light sensor tag chip is in a first brightness environment, the energy management unit controls the photovoltaic cell charge pump combination circuit to supply power; When the light sensor tag chip is in a second brightness environment, the energy management unit controls the full-differential rectifier circuit to supply power; The brightness value of the first brightness environment is greater than a preset brightness threshold value, and the brightness value of the second brightness environment is less than the preset brightness threshold value.

8. A communication system, characterized by For BLE passive backscatter communication, comprising a carrier transmitter for transmitting a carrier signal to the energy supply system of the optical sensor tag chip, a 2.4 GHz transmitter for transmitting a 2.4 GHz carrier to the modulation circuit of the optical sensor tag chip, the optical sensor tag chip for collecting ambient light to generate a communication signal and transmitting the communication signal to the mobile device.

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