Low-voltage cold start circuit system for energy acquisition circuit

Abstract

The invention relates to the field of circuits, and discloses a low-voltage cold start circuit system for an energy acquisition circuit, which comprises a low-power-consumption ring oscillator and a multi-stage cascade boost charge pump, and is characterized in that the low-power-consumption ring oscillator is used for generating a non-overlapping anti-phase clock signal when a first input voltage is lower than a preset threshold value; the voltage input end of the multi-stage cascade boost charge pump is connected with the direct-current voltage output by the micro-photovoltaic panel and forms a second input voltage, the clock input end of the multi-stage cascade boost charge pump is connected with the non-overlapping anti-phase clock signal output by the low-power-consumption ring oscillator, the second input voltage is gradually boosted to the target voltage, and the multi-stage cascade boost charge pump is connected to the energy acquisition circuit. According to the low-power-consumption ring oscillator, the low-power-consumption ring oscillator can autonomously complete self-excitation starting and generate a non-overlapping anti-phase clock signal, the starting reliability and starting efficiency of the micro-energy collection chip are improved, the low-power-consumption ring oscillator can efficiently drive the multi-stage cascade boost charge pump to achieve rapid transfer and step-by-step boosting of charges, and the boosting efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of circuit technology, and more specifically to a low-voltage cold-start circuit system for energy harvesting circuits. Background Technology

[0002] In the current era of rapid development of the global intelligent industry, technological iterations in fields such as the Internet of Things and embedded control systems are accelerating. Various intelligent terminal products are evolving towards miniaturization, integration, and modularization. Low power consumption and low carbon emissions have become the core themes and inevitable trends of industry development. Against this backdrop, micro-energy harvesting technology stands out with its unique advantages: micro-energy harvesting technology can efficiently collect low-grade energy such as light energy, mechanical energy, electromagnetic energy, and thermal energy that are widely present in the environment and convert them into electrical energy, thereby supporting terminal products to achieve battery-free autonomous operation. This perfectly meets the core needs of the current intelligent industry for sustainable power supply and low environmental impact.

[0003] However, the practical application of micro-energy harvesting technology still faces the following technical challenges: The output voltage of the front-end energy harvester in existing micro energy harvesting chips (such as the Mead Square MF9005 chip) is often extremely low. The subsequent functional circuits inside the chip (such as signal processing circuits, control circuits, etc.) require a stable high voltage bias and clock signal to work normally. In the initial startup stage of the chip, the internal circuits have not yet been activated and cannot generate the required bias voltage and clock signal on their own, making it difficult for the chip to start from the initial state of ultra-low voltage and enter a stable working mode.

[0004] Therefore, existing technologies lack boost circuits that can achieve stable self-starting using ultra-low input voltage without requiring external auxiliary power. Summary of the Invention

[0005] Therefore, the present invention provides a low-voltage cold-start circuit system for energy harvesting circuits, which effectively solves the technical problem of the lack of boost circuits in the prior art that can achieve stable self-starting without external auxiliary power supply and using ultra-low input voltage.

[0006] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution: a low-voltage cold-start circuit system for an energy harvesting circuit, wherein its input terminal is connected to the output terminal of a micro photovoltaic panel, and its output terminal is connected to the energy harvesting circuit, characterized in that it includes: A low-power ring oscillator is provided, with its power supply terminal connected to the DC voltage output by the micro photovoltaic panel to form a first input voltage. The low-power ring oscillator is used to generate a non-overlapping inverted clock signal when the first input voltage is lower than a preset threshold. A multi-stage cascaded boost charge pump connects to the DC voltage output from the micro-photovoltaic panel at its voltage input terminal to form a second input voltage, and connects to the non-overlapping inverted clock signal output from the low-power ring oscillator at its clock input terminal to gradually boost the second input voltage to the target voltage and connect it to the energy harvesting circuit.

[0007] Furthermore, the low-power ring oscillator operates by being powered by the DC voltage of the micro photovoltaic panel without an external clock input.

[0008] Furthermore, the low-power ring oscillator consists of an odd number of low-threshold inverters.

[0009] Furthermore, the low threshold inverter is constructed using two MOS transistors.

[0010] Furthermore, each of the low-threshold inverters provides a 180° phase shift during logic flips, and the total phase shift of an odd number of low-threshold inverters is 180°, so that when the output signal of the last stage low-threshold inverter is fed back to the input of the first stage low-threshold inverter, it is out of phase with the original input signal, forming a continuous oscillation.

[0011] Furthermore, the multi-stage cascaded boost charge pump includes multi-stage cascaded charge pump units; The charge pump unit includes a flying capacitor and a one-way conduction switch; The flying capacitor is used to store and transfer charge, and the unidirectional conduction switch is used to ensure the unidirectional transfer direction of charge.

[0012] Furthermore, the operation of the multi-stage cascaded booster charge pump includes the following steps: When the CK signal is high and the CKb signal is low, the flying capacitor connected to the CK signal is charged and the charge is transferred to the flying capacitor at the rear end. When the CK signal is low and the CKb signal is high, the flying capacitor connected to the CKb signal is charged and the charge is transferred to the flying capacitor at the rear end. Through the alternating drive of the non-overlapping inverted clock signals, the charge of the flying capacitor accumulates step by step, causing the output voltage of the multi-stage cascaded boost charge pump to gradually increase to the target voltage; The flying capacitors are alternately connected to the CK and CKb signals, which are a set of non-overlapping inverted clock signals generated by a low-power ring oscillator.

[0013] Furthermore, it also includes filter capacitors; The output voltage is smoothed by the filter capacitor.

[0014] Compared with the prior art, the present invention has the following advantages: In this invention, the low-power ring oscillator can directly respond to the weak DC voltage output by the micro photovoltaic panel in the micro energy harvesting scenario. It does not need to rely on external auxiliary power supply, pre-charging circuit or other external excitation. It can autonomously complete self-excitation startup and generate non-overlapping inverted clock signal, ensuring that the system can start smoothly from the weak DC voltage cold start state. It provides a stable and continuous clock drive for the subsequent multi-stage cascaded boost charge pump, improving the startup reliability and startup efficiency of the micro energy harvesting chip. Meanwhile, the low-power ring oscillator can directly output a high-frequency square wave non-overlapping inverted clock signal, which can efficiently drive a multi-stage cascaded boost charge pump to achieve rapid charge transfer and step-by-step voltage boost. This not only improves boost efficiency but also has good compatibility, making it suitable for various types of subsequent energy harvesting circuits and load circuits. Attached Figure Description

[0015] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0016] Figure 1 A schematic diagram of a low-voltage cold-start circuit system for an energy harvesting circuit is provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a low-power ring oscillator in an embodiment of the present invention; Figure 3 This is a schematic diagram of the low threshold inverter in an embodiment of the present invention; Figure 4 The following is a waveform diagram of a set of non-overlapping inverted clock signals in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of a multi-stage cascaded booster charge pump in an embodiment of the present invention; Figure 6 The output voltage waveforms before and after filtering are shown in the embodiment of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] like Figure 1 As shown, the present invention provides a low-voltage cold-start circuit system for an energy harvesting circuit. Its input terminal is connected to the output terminal of a micro photovoltaic panel, and its output terminal is connected to an energy harvesting circuit. The micro photovoltaic panel is used to convert ambient light energy into a weak DC voltage, and the energy harvesting circuit is used to harvest energy.

[0019] This invention provides a low-voltage cold-start circuit system for energy harvesting circuits, comprising a low-power ring oscillator and a multi-stage cascaded boost charge pump, with the specific connection method and function as follows: A low-power ring oscillator is connected to the DC voltage output by the micro photovoltaic panel to form the first input voltage. The low-power ring oscillator is used to generate a non-overlapping inverted clock signal when the first input voltage is lower than a preset threshold. A multi-stage cascaded boost charge pump connects to the DC voltage output from a micro-photovoltaic panel at its voltage input terminal to form a second input voltage. Its clock input terminal is connected to the output terminal of a low-power ring oscillator and is connected to a non-overlapping inverted clock signal output from the low-power ring oscillator. The second input voltage is gradually boosted to the target voltage and then connected to the energy harvesting circuit.

[0020] In this invention, the low-power ring oscillator can directly respond to the weak DC voltage output by the micro photovoltaic panel in the micro energy harvesting scenario. It does not need to rely on external auxiliary power supply, pre-charging circuit or other external excitation. It can autonomously complete self-excitation startup and generate non-overlapping inverted clock signal, ensuring that the system can start smoothly from the weak DC voltage cold start state. It provides a stable and continuous clock drive for the subsequent multi-stage cascaded boost charge pump, improving the startup reliability and startup efficiency of the micro energy harvesting chip. Meanwhile, the low-power ring oscillator can directly output a high-frequency square wave non-overlapping inverted clock signal, which can efficiently drive a multi-stage cascaded boost charge pump to achieve rapid charge transfer and step-by-step voltage boost. This not only improves boost efficiency but also has good compatibility, making it suitable for various types of subsequent energy harvesting circuits and load circuits.

[0021] The low-power ring oscillator in this invention adopts an autonomous excitation architecture design. Without any external clock signal input, it can complete the power supply and startup process solely by the weak DC voltage output from the micro photovoltaic panel. No additional external drive module or auxiliary power supply unit is required. This design simplifies the overall system structure, reduces hardware costs, and ensures the autonomy and reliability of the system startup in extremely low-power scenarios, forming an efficient match with the weak energy output characteristics of the micro photovoltaic panel.

[0022] A low-power ring oscillator is used to generate a non-overlapping inverted clock signal when the first input voltage is lower than a preset threshold. The specific structure of the low-power ring oscillator is as follows: like Figure 2 As shown, the low-power ring oscillator consists of an odd number of low-threshold inverters.

[0023] The configuration of an odd number of low-threshold inverters ensures that each low-threshold inverter provides a 180° phase shift during logic flips, and the total phase shift of the odd number of low-threshold inverters is an odd multiple of 180°, resulting in an equivalent phase shift of 180°.

[0024] In the formula, For the total phase shift, N is the number of low-threshold inverters. In a circuit structure with an odd number of low-threshold inverters connected in series, the signal is input from the first-stage low-threshold inverter, transmitted sequentially through each stage of low-threshold inverters, and finally output from the last stage of low-threshold inverter. At this time, the total phase of the output signal and the input signal is exactly reversed by 180° (i.e., the output signal is completely opposite to the input signal). When the output signal of the final low-threshold inverter is fed back to the input of the first low-threshold inverter, it is out of phase with the original input signal, thus generating continuous oscillation, such as... Figure 4 The figure shows a waveform of a set of non-overlapping inverted clock signals generated by the aforementioned low-power ring oscillator.

[0025] Based on this phase control mechanism, an odd number of low-threshold inverters can autonomously form a stable oscillation circuit, thereby continuously generating a non-overlapping inverted clock signal that meets the driving requirements, providing timing assurance for the operation of a multi-stage cascaded boost charge pump.

[0026] In the low-power ring oscillator design of this invention, conventional standard inverters are limited by threshold voltage and cannot achieve effective logic switching under the extremely low input voltage conditions faced by this system, thus failing to stably generate clock signals. Therefore, this invention employs a low-threshold inverter, which is constructed from two low-threshold MOS transistors (e.g., Figure 3 As shown, it can adapt to the weak voltage output of micro photovoltaic panels, ensuring that the low-power ring oscillator can start smoothly and output a stable clock signal under ultra-low voltage.

[0027] Based on this, the overall circuit structure of the present invention does not introduce discrete components such as inductors and large-capacity capacitors, which effectively simplifies the circuit topology, reduces the chip layout area, and lowers the chip manufacturing cost. In addition, the circuit structure also has excellent process compatibility, is compatible with existing CMOS processes, fits the current development trend of miniaturization, integration, and modularization of smart terminals, and can adapt to the integrated design requirements of micro-energy harvesting chips, laying the foundation for their engineering application in scenarios such as IoT micro-sensor nodes and portable low-power electronic devices.

[0028] In this invention, the function of the multi-stage cascaded boost charge pump is to receive a non-overlapping inverted clock signal output from a low-power ring oscillator. This non-overlapping inverted clock signal drives the orderly transfer and accumulation of charge, thereby gradually boosting the second input voltage (the weak DC voltage output from the micro-photovoltaic panel) to the target voltage required for the energy harvesting circuit, and then stably outputting it to the energy harvesting circuit. The specific structure of the multi-stage cascaded boost charge pump is as follows: like Figure 5 As shown, the multi-stage cascaded boost charge pump includes a multi-stage cascaded charge pump unit; The charge pump unit includes a flying capacitor and a unidirectional conduction switch; Among them, the flying capacitor is used to store and transfer charge, providing energy carrier for the step-by-step voltage increase, and the one-way conduction switch is used to ensure the unidirectional transmission direction of charge, ensuring that the charge flows only in one direction along the voltage boost direction, avoiding the problem of reduced boost efficiency or voltage instability caused by charge backflow, and ensuring the high efficiency and stability of the boost process under the multi-stage cascaded architecture.

[0029] The multi-stage cascaded boost charge pump provided by this invention is shown in the figure. C1~Cn are flying capacitors, D1~Dn are unidirectional conduction switches with a conduction voltage drop of <0.2V (effectively reducing energy loss during charge transfer) to ensure unidirectional charge transfer, p1~pn are the nodes of the circuit, i1~in are the currents formed during charge transfer, VI is the second input voltage, and VO is the output voltage. The working process of a multi-stage cascaded booster charge pump includes the following steps: When the CK signal is high and the CKb signal is low, the flying capacitors C1, C3, C5, ... connected to the CK signal are charged. VI charges C1, C2 charges C3, C4 charges C5, and so on, thus sequentially transferring charge to the flying capacitor at the rear. When the CK signal is low and the CKb signal is high, the flying capacitors C2, C4, C6, ... connected to the CKb signal are charged. C1 charges C2, C3 charges C4, and so on, thus sequentially transferring charge to the flying capacitor at the rear. Driven by the alternating non-overlapping inverted clock signals, the charge of the flying capacitors C1, C2, C3, ... accumulates step by step over time, and the positive / negative potential of the flying capacitor Cn in the output stage becomes higher and higher, so that the output voltage of the multi-stage cascaded boost charge pump gradually increases to the target voltage. It should be noted that the CK and CKb signals mentioned above are a set of non-overlapping inverted clock signals generated by a low-power ring oscillator. The flying capacitors are alternately connected to the CK and CKb signals to ensure the orderliness and continuity of charge transfer.

[0030] In addition, this system also integrates filter capacitors, such as Figure 1 and Figure 6 As shown ( Figure 1 (Co is the filter capacitor). The voltage signal output by the multi-stage cascaded boost charge pump is filtered by the filter capacitor to obtain a smooth voltage, which further improves the stability of the output voltage and provides power supply guarantee for the stable operation of the subsequent energy harvesting circuit.

[0031] The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. The scope of protection of this application is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this application within its substance and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this application.

Claims

1. A low-voltage cold-start circuit system for an energy harvesting circuit, wherein its input terminal is connected to the output terminal of a micro photovoltaic panel, and its output terminal is connected to the energy harvesting circuit, characterized in that, include: A low-power ring oscillator is provided, with its power supply terminal connected to the DC voltage output by the micro photovoltaic panel to form a first input voltage. The low-power ring oscillator is used to generate a non-overlapping inverted clock signal when the first input voltage is lower than a preset threshold. A multi-stage cascaded boost charge pump connects to the DC voltage output from the micro-photovoltaic panel at its voltage input terminal to form a second input voltage, and connects to the non-overlapping inverted clock signal output from the low-power ring oscillator at its clock input terminal to gradually boost the second input voltage to the target voltage and connect it to the energy harvesting circuit.

2. The low-voltage cold-start circuit system for energy harvesting circuits according to claim 1, characterized in that, The low-power ring oscillator operates by being powered by the DC voltage of the micro photovoltaic panel without an external clock input.

3. The low-voltage cold-start circuit system for energy harvesting circuits according to claim 1 or 2, characterized in that, The low-power ring oscillator consists of an odd number of low-threshold inverters.

4. The low-voltage cold-start circuit system for energy harvesting circuits according to claim 3, characterized in that, The low threshold inverter is constructed using two MOS transistors.

5. The low-voltage cold-start circuit system for energy harvesting circuits according to claim 3, characterized in that, Each of the low-threshold inverters provides a 180° phase shift during logic flips, and the total phase shift of an odd number of low-threshold inverters is 180°, so that when the output signal of the last stage low-threshold inverter is fed back to the input of the first stage low-threshold inverter, it is out of phase with the original input signal, forming a continuous oscillation.

6. The low-voltage cold-start circuit system for energy harvesting circuits according to claim 1, characterized in that, The multi-stage cascaded boost charge pump includes a multi-stage cascaded charge pump unit; The charge pump unit includes a flying capacitor and a one-way conduction switch; The flying capacitor is used to store and transfer charge, and the unidirectional conduction switch is used to ensure the unidirectional transfer direction of charge.

7. The low-voltage cold-start circuit system for energy harvesting circuits according to claim 6, characterized in that, The operation of the multi-stage cascaded booster charge pump includes the following steps: When the CK signal is high and the CKb signal is low, the flying capacitor connected to the CK signal is charged and the charge is transferred to the flying capacitor at the rear end. When the CK signal is low and the CKb signal is high, the flying capacitor connected to the CKb signal is charged and the charge is transferred to the flying capacitor at the rear end. Through the alternating drive of the non-overlapping inverted clock signals, the charge of the flying capacitor accumulates step by step, causing the output voltage of the multi-stage cascaded boost charge pump to gradually increase to the target voltage; The flying capacitors are alternately connected to the CK and CKb signals, which are a set of non-overlapping inverted clock signals generated by a low-power ring oscillator.

8. The low-voltage cold-start circuit system for energy harvesting circuits according to claim 7, characterized in that, It also includes filter capacitors; The output voltage is smoothed by the filter capacitor.

Images