Optical sensor label chip and communication method and communication system thereof

Abstract

The invention 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 fully differential rectification circuit, a photocell charge pump combination circuit and an energy management unit, the fully differential rectification circuit and the photocell 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, and the optical sensor is used for converting an optical signal into an electric signal and generating a first transmission signal; the digital baseband is electrically connected with the analog front end, and the digital baseband is used for carrying out coding verification processing on the first transmission signal and generating a second transmission signal; and the modulation circuit is electrically connected with the digital base band and is used for modulating the second transmission signal and transmitting the second transmission signal to the mobile equipment, so that the application range of the optical sensor tag chip can be expanded.

Description

Technical Field

[0001] The present invention belongs to the field of communication technology, and in particular relates to an optical sensor tag chip and a communication method and a communication system thereof. Background Art

[0002] Generally speaking, after decades of development, the Internet of Things (IoT) technology has been widely used in various fields such as smart homes, smart cities, smart agriculture, logistics and transportation, and biomedicine. IoT technologies mainly include Radio Frequency Identification (RFID), Bluetooth, WiFi, and ZigBee. RFID electronic tags have gradually been applied to the field of identification technology. RFID electronic tags mainly consist of three parts: tag chips, readers, and data transmission and processing systems. The optical sensor tag chip is a microchip that integrates optical sensing and wireless communication functions. It senses the changes in light in the environment, converts optical signals into electrical signals, and further modulates the electrical signals onto wireless communication signals to achieve data transmission.

[0003] The common optical sensor tag chip currently includes an optical sensor, an oscillator, a memory and a processing system, wherein the oscillator is used to provide a clock signal to ensure that the tag can work properly, the timer is used to regularly send and receive data, the optical sensor is used to collect optical signals and convert them into electrical signals, and the processing system is used to process the electrical signals to generate communication signals and output the communication signals to the reader, thereby realizing the collection and communication of ambient light. However, the above-mentioned tag chip is a semi-active chip, which is powered by a battery or uses solar energy to charge and power the battery, resulting in the tag chip not being able to work properly under certain extreme weather conditions, which in turn leads to a limited scope of application of the tag chip. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a light sensor tag chip and a communication method and a communication system thereof. The technical problem to be solved by the present invention is achieved by the following technical solutions:

[0005] In a first aspect, the present invention provides a light sensor tag chip, comprising:

[0006] An energy supply system, comprising a fully differential rectifier circuit, a photocell charge pump combination circuit and an energy management unit, wherein the fully differential rectifier circuit is used to receive radio frequency signals and convert the radio frequency signals into direct current energy, the photocell charge pump combination circuit is used to collect ambient light and generate current, the fully differential rectifier circuit and the photocell charge pump combination circuit are both electrically connected to the energy management unit, and the energy management unit is used to control the fully differential rectifier circuit and / or the photocell charge pump combination circuit to supply power;

[0007] An analog front end is electrically connected to the energy supply system, and the analog front end includes a light sensor, and the light sensor is used to convert the light signal into an electrical signal and generate a first transmission signal;

[0008] A digital baseband is electrically connected to the analog front end, and is used to perform coding verification processing on the first transmission signal and generate a second transmission signal;

[0009] The modulation circuit is electrically connected to the digital baseband and is used for modulating the second transmission signal and transmitting the second transmission signal to the mobile device.

[0010] In one embodiment of the present invention, the energy supply system further includes a PMOS tube and a capacitor C1, the source of the PMOS tube is connected to the differential rectifier circuit, the gate of the PMOS tube is connected to the photocell 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;

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

[0012] In one embodiment of the present invention, the analog front end also includes a reference circuit, a low-voltage dropout linear regulator and a reset circuit. The energy supply system, the low-voltage dropout linear regulator and the optical sensor are all electrically connected to the reference circuit. The reference circuit is used to provide a bias current, a bias voltage and a reference voltage. The low-voltage dropout linear regulator is used to stabilize the current provided by the energy supply system and generate a power supply voltage. The reset circuit is used to generate a reset signal.

[0013] In one embodiment of the present invention, it also includes a clock module, which is used to provide a clock signal. The analog front end also includes a frequency division circuit. The digital baseband, the modulation circuit and the clock module are all electrically connected to the frequency division circuit. The frequency division circuit is used to divide the clock signal and transmit the clock signal to the digital baseband and the modulation circuit.

[0014] In one embodiment of the present invention, the clock module includes 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. One end of the demodulation circuit is connected to the envelope detection circuit, and the other end is connected to the frequency division circuit.

[0015] In one embodiment of the present invention, the optical sensor includes a photodiode, a nonlinear current amplifier, a transimpedance amplifier and a successive approximation analog-to-digital converter 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, and the successive approximation analog-to-digital converter is used to convert the voltage signal output by the transimpedance amplifier into a digital signal and output it to a digital baseband.

[0016] In one embodiment of the present invention, the digital baseband includes a coding module, a process management module, a verification module and an output control module, the coding module is connected to the optical sensor, the coding module, the verification module and the output control module are all connected to the process management module, the coding module, the verification module and the output control module are connected in sequence, and the output control module is connected to the modulation circuit;

[0017] The encoding module is used to encode the first transmission signal output by the optical sensor, the verification module is used to generate a data verification code, the output control module is used to transmit a read / write enable signal and an address signal to the modulation circuit, and the process management module is used to control the encoding module, the verification module and the output control module to work.

[0018] In one embodiment of the present invention, the modulation circuit is an FSK circuit and an MN1 tube, the frequency division circuit and the output control module are both connected to the FSK circuit, the MN1 tube and the frequency division circuit output two clock signals of different frequencies to the FSK circuit, the FSK circuit is used to modulate 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 tube is used to perform backscatter modulation on the signal output by the FSK circuit to obtain the modulated wave of the BLE communication channel.

[0019] In a second aspect, the present invention provides a communication method of an optical sensor tag chip, which is applied to the optical sensor tag chip provided in the above scheme, wherein the optical sensor tag chip includes an energy supply system, the energy supply system includes a fully differential rectifier circuit, a photocell 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 photocell charge pump combination circuit to supply power;

[0021] 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;

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

[0023] In the third aspect, the present invention 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 scheme, the carrier transmitter is used to send a carrier signal to an energy supply system of the light sensor tag chip, the 2.4GHz transmitter is used to send a 2.4GHz carrier to a modulation circuit of the light sensor tag chip, and the light sensor tag chip is used to collect ambient light to generate a communication signal and transmit the communication signal to the mobile device.

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

[0025] In the above scheme of the present application, the optical sensor tag chip includes an energy supply system, an analog front end, a digital baseband and a modulation circuit. The energy supply system includes a fully differential rectifier circuit, a photocell charge pump combination circuit and an energy management unit. The fully differential rectifier circuit is used to receive radio frequency signals and convert radio frequency signals into DC energy. The photocell charge pump combination circuit is used to collect ambient light and generate current. The fully differential rectifier circuit and the photocell charge pump combination circuit are both electrically connected to the energy management unit. The energy management unit is used to control the fully differential rectifier circuit and / or the photocell charge pump combination circuit for power supply. The analog front end is electrically connected to the energy supply system. The analog front end includes a light sensor. The light sensor is used to convert the light 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 verification processing on the first transmission signal and generate a second transmission signal. The modulation circuit is electrically connected to the digital baseband and is used to modulate the second transmission signal and transmit it to the mobile device. In this way, the optical sensor tag chip can realize the collection and communication of ambient light. With this structure, first, the RF signal is received and converted into DC energy through a fully differential rectifier circuit, and the ambient light is collected and current is generated through a photocell charge pump combination circuit, so that the optical sensor tag chip can be powered by both ambient light energy and RF signals. Different power supply methods can be used according to different usage environments, so that the optical sensor tag chip can be suitable for a variety of extreme weather conditions, thereby improving the scope of application of the optical sensor tag chip. In addition, the above-mentioned optical sensor tag chip of the present application can utilize 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 above-mentioned optical sensor tag chip of the present application can be integrated inside the chip, making the optical sensor tag chip more integrated.

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

[0027] Figure 1 is a schematic diagram of a light sensor tag chip provided by an embodiment of the present invention;

[0028] Figure 2 is a schematic diagram of an energy supply system in an embodiment of the present invention;

[0029] Figure 3 is a schematic diagram of an optical sensor in an embodiment of the present invention;

[0030] Figure 4 is a schematic diagram of a photovoltaic cell charge pump combination circuit in an embodiment of the present invention;

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

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

[0033] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0034] After decades of development, the Internet of Things (IoT) technology has been widely used in various fields such as smart homes, smart cities, smart agriculture, logistics and transportation, and biomedicine. IoT technologies mainly include Radio Frequency Identification (RFID), Bluetooth, WiFi, and ZigBee. Among them, RFID is the most mature technology, with the advantages of low cost, long life, and reusability. It is widely used in logistics, management, production, transportation, and other fields.

[0035] Bluetooth Low Energy (BLE) is a personal area network technology designed by the Bluetooth SIG, which can be applied to enterprise IoT, beacons, 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 used low-power Bluetooth standards, which makes every mobile device a potential reader. However, the power consumption of traditional BLE transmitters is still too large compared to the power consumption of backscatter modulation. If the uplink information path of traditional passive tags is changed and backscatter technology is used to transmit data to mobile devices through low-power Bluetooth channels, not only can long-distance mobile communication be achieved, but the energy consumed by backscattering is also much less than the energy consumed by traditional BLE transmitters.

[0036] The application of wireless sensor networks (WSN) is an important part of the development of the Internet of Things. In these practical applications, the collection of sensor information is crucial. A sensor system without information collection has no practical significance. Therefore, the collection and quantification of a variable in the environment by the Internet of Things node or tag is one of the cores of the wireless sensor network. Ambient light sensors are generally composed of photosensitive elements and data conversion modules. Ambient light sensors can convert illumination into electrical signals to achieve the functions of controlling backlight brightness and improving user visual effects. Common traditional light sensors have the disadvantages of large size, high power consumption, and high cost, 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, and high reliability. It can be used in smart homes, environmental monitoring, smart agriculture, etc. to passively collect and quantify ambient light and communicate with mobile devices.

[0037] Embodiment 1:

[0038] See also Figure 1 , Figure 2 , Figure 3 and Figure 6 An embodiment of the present invention provides a light sensor tag chip, including an energy supply system, an analog front end, a digital baseband and a modulation circuit. The energy supply system includes a fully differential rectifier circuit, a photocell charge pump combination circuit and an energy management unit. The fully differential rectifier circuit is used to receive a radio frequency signal and convert the radio frequency signal into direct current energy. The photocell charge pump combination circuit is used to collect ambient light and generate current. The fully differential rectifier circuit and the photocell charge pump combination circuit are both electrically connected to the energy management unit. The energy management unit is used to control the fully differential rectifier circuit and / or the photocell charge pump combination circuit to supply power; the analog front end is electrically connected to the energy supply system, the analog front end includes a light sensor, the light sensor is used to convert the light 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 verification processing on the first transmission signal, and generate a second transmission signal; the modulation circuit is electrically connected to the digital baseband, and is used to modulate the second transmission signal and transmit it to a mobile device.

[0039] In some embodiments of the present application, a fully differential rectifier circuit (RECT) is a circuit structure that rectifies AC power into DC power. A common fully 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 fully differential rectifier circuit RECT can convert the AC carrier signal received by the antenna into a DC signal.

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

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

[0042] In some embodiments of the present application, Figure 2 and Figure 3 As shown, the photovoltaic cell charge pump combination circuit Phot ocellCP includes a photovoltaic cell group and a three-stage cascade charge pump. The photovoltaic cell group is composed of photodiodes integrated on the chip in parallel. The negative poles of all photodiodes are grounded, and the positive poles are output to the three-stage cascade charge pump as the light energy collection output terminal. Since the voltage of a conventional single-junction photovoltaic cell is less than 0.5V, a PN junction series connection is used for boosting. The standard CMOS process is adopted. Taking the P+ / NWELL type PN junction as an example, the first-stage structure is consistent with the single-stage photodiode. NWEL and PSUB are led out through a metal short circuit as the negative pole of the photovoltaic cell as a whole. The P terminal is interconnected with the second-stage NWELL through a metal connection to complete the series connection of the two-stage photovoltaic cells. The second-stage P terminal is led out as the positive pole of the photovoltaic cell as a whole. By Figure 3 From the circuit model diagram, it can be seen that the parasitic transistor of the first stage is shielded by short circuit.

[0043] In some embodiments of the present application, a power management unit (PMU) is a highly integrated microcontroller that is mainly used to control the power function of a digital platform. The power management unit PMU integrates traditional discrete power management devices (such as low dropout linear regulators (LDOs), direct current converters (DC / DC), etc.) into a single package to achieve higher power conversion efficiency, lower power consumption, and fewer components to adapt to 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 optical 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. The core of the BLE backscatter communication system is to transmit data by reflecting or scattering incident BLE signals without actively transmitting radio frequency signals. This technology is similar to the principle of radar. When electromagnetic waves encounter objects, part of their energy will be reflected, and the strength of the reflected signal depends on the shape, material and distance of the object. By changing the intensity 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 photovoltaic cell group outputs a photovoltaic voltage at the positive electrode, but this voltage is still insufficient for the subsequent circuit to work normally. To solve this problem, a charge pump is required at the photovoltage output end to boost the voltage again. When the light sensor tag chip is in an environment with low light intensity, it can be considered that the voltage output by the charge pump is low. At this time, the energy management unit switches to a fully differential rectifier circuit to use RF energy for power supply.

[0047] In some embodiments of the present application, a light sensor is a device that can convert light energy into an electrical signal, and is mainly used to detect light energy ranging from ultraviolet light to infrared light. The light sensor is mainly composed of photosensitive elements and can be divided into types such as ambient light sensors, infrared light sensors, sunlight sensors, and ultraviolet light sensors. 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 optical sensor tag chip of the present application has low power consumption, is highly integrated, does not require external power supply voltage, can be applied to a variety of ambient light detection scenarios, and can communicate with mobile devices over long distances. After collecting and quantizing ambient light, data can be transmitted to mobile devices by backscattering.

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

[0050] In the above scheme of the present application, the optical sensor tag chip includes an energy supply system, an analog front end, a digital baseband and a modulation circuit. The energy supply system includes a fully differential rectifier circuit, a photocell charge pump combination circuit and an energy management unit. The fully differential rectifier circuit is used to receive radio frequency signals and convert radio frequency signals into DC energy. The photocell charge pump combination circuit is used to collect ambient light and generate current. The fully differential rectifier circuit and the photocell charge pump combination circuit are both electrically connected to the energy management unit. The energy management unit is used to control the fully differential rectifier circuit and / or the photocell charge pump combination circuit for power supply. The analog front end is electrically connected to the energy supply system. The analog front end includes a light sensor. The light sensor is used to convert the light 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 verification processing on the first transmission signal and generate a second transmission signal. The modulation circuit is electrically connected to the digital baseband and is used to modulate the second transmission signal and transmit it to the mobile device. In this way, the optical sensor tag chip can realize the collection and communication of ambient light. With this structure, first, the RF signal is received and converted into DC energy through a fully differential rectifier circuit, and the ambient light is collected and current is generated through a photocell charge pump combination circuit, so that the optical sensor tag chip can be powered by both ambient light energy and RF signals. Different power supply methods can be used according to different usage environments, so that the optical sensor tag chip can be suitable for a variety of extreme weather conditions, thereby improving the scope of application of the optical sensor tag chip. In addition, the above-mentioned optical sensor tag chip of the present application can utilize 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 above-mentioned optical sensor tag chip of the present application can be integrated inside the chip, making the optical sensor tag chip more integrated.

[0051] In some embodiments of the present application, Figure 2 As shown, the energy supply system also includes a PMOS tube and a capacitor C1, the source of the PMOS tube is connected to the differential rectifier circuit, the gate of the PMOS tube is connected to the photocell 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 off according to the voltage of the capacitor C1, and 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 photocell charge pump combination circuit and the full differential rectifier circuit, and the energy management unit PMU can control the photocell 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 being powered by RF energy, and a portion of energy will be stored on the capacitor C1, so that the energy management unit PMU can be charged to the start-up voltage faster when switching to RF power supply.

[0052] In some embodiments of the present application, Figure 2 As shown, the PMOS tube is the MP1 tube. When the ambient light is weak, the combination of the photocell and the charge pump can hardly reach the voltage required for the normal operation of the subsequent circuit. At this time, the MP1 tube in the energy supply system is turned on, and 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, the entire chip is in a working state, and the energy supply system supplies power to the subsequent circuit; when the charge of the capacitor C1 is consumed to a certain extent, the voltage drops and is not enough to make the subsequent circuit continue to work. The energy management unit PMU is turned off, and the chip is in a standby state. At this time, no energy is consumed, and the rectifier or charge pump continues to charge the capacitor C1 until the next work can start.

[0053] In some embodiments of the present application, Figure 1 As shown, the analog front end also includes a reference circuit, a low-voltage dropout linear regulator and a reset circuit. The energy supply system, the low-voltage dropout linear regulator and the optical sensor are all electrically connected to the reference circuit. The reference circuit is used to provide bias current, bias voltage and reference voltage. The low-voltage dropout linear regulator is used to stabilize the current provided by the energy supply system and generate a power supply voltage VDD. 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 a reference voltage for the low-voltage dropout linear regulator, so that the low-voltage dropout linear regulator can stabilize the reference voltage and generate a power supply voltage VDD. The power supply voltage VDD can power each module of the analog front end and the digital baseband. The reset circuit can generate a voltage jump signal used as a reset switch. When starting to work, the reset signal is later than the power supply voltage VDD. When the digital baseband receives the reset signal, it starts to work normally, ensuring that the optical sensor tag chip can work normally.

[0054] In some embodiments of the present application, a reference circuit (REF) is an existing circuit for providing a 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, a low dropout regulator (LDO) is an existing regulator capable of maintaining a stable output voltage, and its core advantage is that it can maintain a stable output voltage when the voltage difference between the input voltage and the output voltage is very 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 through the reference circuit REF. The low-dropout linear regulator LDO then amplifies and stabilizes the reference voltage to provide the power supply voltage VDD for the entire analog front end and digital baseband.

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

[0058] In some embodiments of the present application, the optical sensor tag chip also includes a clock module, which is used to provide a clock signal. The analog front end also includes a frequency division circuit. The digital baseband, the modulation circuit and the clock module are all electrically connected to the frequency division circuit. 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 to the analog front end, so that the optical sensor tag chip can work normally; when the clock signal is divided by the frequency division circuit and the clock signal is transmitted to the digital baseband and the modulation circuit, it can ensure that the clock signal can be transmitted to the digital baseband to ensure that the digital baseband can work normally, and the modulation circuit can use two clock signals of different frequencies for modulation. In addition, since the traditional on-chip clock of the tag is difficult to meet the standards of the BLE backscatter system due to the influence of PVT, this embodiment adopts an external clock acquisition method, uses the clock module to obtain the clock signal and provides it to the analog front end for the next step of processing, so as to meet the standards 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 for use as the clock signal CLK. 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 with different frequencies. These two signals F_0 and F_1 are used for use by the modulation circuit.

[0060] In some embodiments of the present application, the clock module includes 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. 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. Among them, 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, an envelope detection circuit (Envelope Detection, ED) is an existing circuit for extracting a modulated signal from a modulated signal. The envelope detection circuit realizes demodulation of an amplitude modulated signal through rectification and filtering processes.

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

[0063] In some embodiments of the present application, Figure 4 As shown, the optical sensor includes a photodiode (Diode), a nonlinear current amplifier, a transimpedance amplifier (RTIA) and a successive approximation 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 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 a photoconductive mode and is used to convert the ambient light illumination into a photocurrent. Since the human eye has a nonlinear response range to light intensity, a nonlinear current amplifier is used to perform nonlinear fitting amplification on the photocurrent output by the photodiode. The transimpedance amplifier is used to convert the processed photocurrent into a photovoltage signal for output. The obtained photovoltage signal is quantized by a successive approximation analog-to-digital converter and output to the digital baseband. Since the photodiode needs to work under a reverse bias voltage, a bias voltage Vbias is connected to its negative pole, and this voltage can be provided by a reference circuit.

[0064] In some embodiments of the present application, the ambient light sensor quantifies the ambient light when the power supply voltage VDD is stable. The specific steps are as follows: the photodiode is reverse biased due to Vbias, and the illuminance received by the light sensor tag chip is converted into a photocurrent Iin. At the same time, in order to handle a wider range of illuminance response, a nonlinear current amplifier is used to convert the current into a current proportional to √Iin, i.e., Iout. The output of the nonlinear current amplifier is connected to the negative input of the transimpedance amplifier, and the feedback resistor Rf is connected to the positive input and output of the transimpedance amplifier to convert the current Iout into a photovoltage. The photovoltage is then quantized by a 10-bit successive approximation analog-to-digital converter SAR ADC to output a 10-bit digital code Data[9:0].

[0065] In some embodiments of the present application, the digital baseband includes an encoding module (ENCODE), a process management unit (PMU), a check module (CRC) and an output control module (OCU), the encoding module is connected to the optical sensor, the encoding module, the check module and the output control module are all connected to 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 to the modulation circuit; the encoding module is used to encode the first transmission signal output by the optical sensor, the check module is used to generate a data check code, the output control module is used to transmit a read / write enable signal (Ble_en) and an address signal (Ble_data) to the modulation circuit, and the process management module is used to control 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. Among them, the encoding module ENCODE is used to encode the 10-bit data of the ambient light sensor for light quantization; the verification module CRC is used to generate a data verification code, and the mobile device can determine whether the data is correct based on the verification code; the output control module OCU is used to transmit the relevant read / write enable signal (Ble_en) and address signal (Ble_data) to the modulation circuit; the process management module PMU is used to control the workflow of each module.

[0067] In some embodiments of the present application, Figure 5 As shown in the figure, after the light sensor ALS quantifies the ambient light, it sends the data Data[9:0] to the digital baseband. The workflow of the digital baseband is as follows: Figure 5 . When the tag enters the BLE working mode, the process management unit module starts to work, first reading the BLE configuration data and ID data, and managing the data flow processing process by controlling the clock of each module. After the data is encoded and encrypted, the CRC module generates a CRC check code, and then whitens the data and the check code to obtain the whitened data. Next, the framing module combines the preamble, address, quantized data and CRC check code in sequence and outputs them serially, and generates an enable signal Ble_en at the same time.

[0068] In some embodiments 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 to the FSK circuit, the MN1 tube and the frequency division circuit output two clock signals of different frequencies to the FSK circuit, the FSK circuit is used to modulate 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 tube is used to backscatter modulate the signal output by the FSK circuit to obtain the 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 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 technology that transmits digital information by changing the frequency of a carrier signal. In FSK, two different frequencies are usually used to represent the numbers 0 and 1. When sending the number 1, the frequency of the carrier will switch to a specific value; and when sending the number 0, the frequency of the carrier will switch to another specific value. The receiving end determines whether 0 or 1 is sent based on the received signal frequency, thereby restoring 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, whose gate is connected to the FSK circuit, the source is grounded, and the drain receives a 2.4 GHz carrier.

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

[0072] Embodiment 2:

[0073] This embodiment provides a communication method of an optical sensor tag chip, which is applied to the optical sensor tag chip provided in the above-mentioned embodiment 1. The optical sensor tag chip includes an energy supply system, and the energy supply system includes a fully differential rectifier circuit, a photocell charge pump combination circuit and an energy management unit. The method includes:

[0074] When the light sensor tag chip is in a first brightness environment, the energy management unit controls the photocell 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, and the brightness value of the second brightness environment is less than the preset brightness threshold.

[0077] The beneficial effects of the second embodiment of the present invention and its various implementations can be analyzed by referring to the beneficial effects of the first embodiment and its various implementations, which will not be described in detail here.

[0078] Embodiment three:

[0079] See also Figure 6 This embodiment provides a communication system, which is 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 embodiment 1, wherein the carrier transmitter is used to send a carrier signal to an energy supply system of the light sensor tag chip, the 2.4GHz transmitter is used to send a 2.4GHz carrier to a modulation circuit of the light sensor tag chip, and the light sensor tag chip is used to collect ambient light to generate a communication signal, and transmit 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 an ASK circuit. The transmitted carrier is used to provide energy and an external clock to the tag chip. The tag can rectify the carrier energy through the corresponding antenna to power the chip. At the same time, the clock acquisition module in the tag extracts the envelope in the high-frequency carrier by means of envelope detection. The extracted envelope signal usually contains some high-frequency components or noise, which needs to be filtered by a bandpass filter. The filtered low-frequency signal generates a reference voltage through a peak detection circuit, and finally the low-frequency signal is compared with the reference voltage through a hysteresis comparator to recover and output the 2M clock.

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

[0082] In some embodiments of the present application, the 2.4 GHz transmitter is used to send a 2.4 GHz carrier to the modulation circuit. The tag modulates the 2.4 GHz carrier and reflects it as a Bluetooth signal that meets the BLE communication standard, and finally the signal is received by a mobile device.

[0083] The beneficial effects of the second embodiment of the present invention and its various implementations can be analyzed by referring to the beneficial effects of the first embodiment and its various implementations, which will not be described in detail here.

[0084] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0085] Although the present application is described herein in conjunction with various embodiments, in the process of implementing the claimed application, those skilled in the art may understand and implement other variations of the disclosed embodiments by viewing the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "one" or "an" does not exclude multiple situations. A single processor or other unit may implement several functions listed in a claim. Certain measures are recorded in different dependent claims, but this does not mean that these measures cannot be combined to produce good results.

[0086] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, devices (equipment), or computer program products. Therefore, the present application may adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware, which are collectively referred to as "modules" or "systems" herein. Moreover, the present application may adopt the form of computer program products implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program codes. The computer program is stored / distributed in a suitable medium, provided together with other hardware or as a part of hardware, or may adopt other distribution forms, such as by Internet or other wired or wireless telecommunication systems.

[0087] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A light sensor tag chip, characterized in that: include: An energy supply system, comprising a fully differential rectifier circuit, a photocell charge pump combination circuit and an energy management unit, wherein the fully differential rectifier circuit is used to receive a radio frequency signal and convert the radio frequency signal into direct current energy, the photocell charge pump combination circuit is used to collect ambient light and generate current, the fully differential rectifier circuit and the photocell charge pump combination circuit are both electrically connected to the energy management unit, and the energy management unit is used to control the fully differential rectifier circuit and / or the photocell charge pump combination circuit to supply power; An analog front end, electrically connected to the energy supply system, the analog front end comprising a light sensor, the light sensor being used to convert an optical signal into an electrical signal and generate a first transmission signal; A digital baseband, electrically connected to the analog front end, the digital baseband being used to perform coding verification processing on the first transmission signal and generate a second transmission signal; The modulation circuit is electrically connected to the digital baseband and is used to modulate the second transmission signal and transmit it to the mobile device.

2. The optical sensor tag chip according to claim 1, characterized in that: The energy supply system further includes a PMOS tube and a capacitor C1, the source of the PMOS tube is connected to the differential rectifier circuit, the gate of the PMOS tube is connected to the photocell 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 off according to the voltage of the capacitor C1.

3. The optical sensor tag chip according to claim 1, characterized in that: The analog front end also includes a reference circuit, a low-voltage dropout linear regulator and a reset circuit. The energy supply system, the low-voltage dropout linear regulator and the optical sensor are all electrically connected to the reference circuit. The reference circuit is used to provide a bias current, a bias voltage and a reference voltage. The low-voltage dropout linear regulator is used to stabilize the current provided by the energy supply system and generate a power supply voltage. The reset circuit is used to generate a reset signal.

4. The optical sensor tag chip according to claim 3, characterized in that: It also includes a clock module, which is used to provide a clock signal. The analog front end also includes a frequency division circuit. The digital baseband, modulation circuit and clock module are all electrically connected to the frequency division circuit. The frequency division circuit is used to divide the clock signal and transmit the clock signal to the digital baseband and the modulation circuit.

5. The optical sensor tag chip according to claim 4, characterized in that: The clock module includes 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. One end of the demodulation circuit is connected to the envelope detection circuit, and the other end is connected to the frequency division circuit.

6. The optical sensor tag chip according to claim 1, characterized in that: The light sensor includes a photodiode, a nonlinear current amplifier, a transimpedance amplifier, and a successive approximation analog-to-digital converter connected in sequence, wherein 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, and the successive approximation 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.

7. The optical sensor tag chip according to claim 5, characterized in that: The digital baseband includes a coding module, a process management module, a verification module and an output control module, the coding module is connected to the optical sensor, the coding module, the verification module and the output control module are all connected to the process management module, the coding module, the verification module and the output control module are connected in sequence, and the output control module is connected to the modulation circuit; The encoding module is used to encode the first transmission signal output by the optical sensor, the verification module is used to generate a data verification code, the output control module is used to transmit a read / write enable signal and an address signal to the modulation circuit, and the process management module is used to control the encoding module, the verification module and the output control module to work.

8. The optical sensor tag chip according to claim 7, characterized in that: The modulation circuit is an FSK circuit and an MN1 tube. The frequency division circuit and the output control module are both connected to the FSK circuit. The MN1 tube and the frequency division circuit output two clock signals of different frequencies to the FSK circuit. The FSK circuit is used to modulate the signal transmitted by the output control module according to the two clock signals of different frequencies output by the frequency division circuit. The MN1 tube is used to perform backscatter modulation on the signal output by the FSK circuit to obtain the modulated wave of the BLE communication channel.

9. A communication method for an optical sensor tag chip, characterized in that: Applied to the optical sensor tag chip according to any one of claims 1 to 8, the optical sensor tag chip includes an energy supply system, the energy supply system includes a fully differential rectifier circuit, a photocell charge pump combination circuit and an energy management unit, the method includes: When the light sensor tag chip is in a first brightness environment, the energy management unit controls the photocell 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 fully differential rectifier circuit to supply power; The brightness value of the first brightness environment is greater than a preset brightness threshold, and the brightness value of the second brightness environment is less than the preset brightness threshold.

10. A communication system, characterized in that: Applied to BLE passive backscatter communication, including a carrier transmitter, a 2.4GHz transmitter, a mobile device and a light sensor tag chip as described in any one of claims 1 to 8, wherein the carrier transmitter is used to send a carrier signal to an energy supply system of the light sensor tag chip, the 2.4GHz transmitter is used to send a 2.4GHz carrier to a modulation circuit of the light sensor tag chip, and the light sensor tag chip is used to collect ambient light to generate a communication signal, and transmit the communication signal to the mobile device.

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