RF-DC Rectifier And Energy Harvesting Device Including the Same

Abstract

An RF-DC rectifier circuit for rectifying an antenna output voltage converted from RF energy according to one embodiment of the present invention is characterized by rectifying the antenna output voltage using a first diode which is an NMOS transistor, a second diode which is a PMOS transistor, and a capacitor to output an energy harvesting current.

Description

Technology Field

[0001] This specification relates to an RF-DC rectifier and an energy harvesting device including the same. Background Technology

[0002] An energy harvesting device receives energy from an external energy source, such as light, heat, radio waves, pressure, etc., converts the received energy into electrical energy, and collects the converted electrical energy to charge a battery. Such an energy harvesting device may include a circuit for converting energy received from an external energy source into electrical energy and effectively charging the converted electrical energy into a battery. The problem to be solved

[0003] The technical objective of the present invention is to provide an RF-DC rectifier that outputs a high and stable voltage and an energy harvesting device including the same. means of solving the problem

[0004] An RF-DC rectifier circuit for rectifying an antenna output voltage converted from RF energy according to one embodiment of the present invention is characterized by rectifying the antenna output voltage using a first diode which is an NMOS transistor, a second diode which is a PMOS transistor, and a capacitor to output an energy harvesting current.

[0005] In addition, an energy harvesting device according to one embodiment of the present invention comprises: an RF energy conversion unit that converts ambient RF energy to output an energy harvesting current; and an energy storage unit that receives and stores the energy harvesting current and outputs a first auxiliary voltage from the stored power; wherein the RF energy conversion unit comprises: an antenna unit including an antenna that collects ambient RF energy and outputs an antenna output voltage; and an RF-DC rectification circuit unit that rectifies the antenna output voltage using a first diode which is an NMOS transistor, a second diode which is a PMOS transistor, and a capacitor, and outputs the energy harvesting current. Effects of the invention

[0006] The RF-DC rectifier according to the present invention and the energy harvesting device including the same have the effect of outputting a stable and high voltage compared to an RF-DC rectifier circuit composed only of NMOS transistors and an RF-DC rectifier circuit composed only of PMOS transistors, by including an NMOS transistor having a high threshold voltage and a low turn-on resistance and a PMOS transistor having a low threshold voltage and a high turn-on resistance.

[0007] In addition, the RF-DC rectifier according to the present invention and the energy harvesting device including the same have the effect of including an RF-DC rectifier circuit that rectifies electrical energy converted from RF energy, so that an RF energy conversion unit that converts RF energy into electrical energy can be directly connected to an energy storage unit. Brief explanation of the drawing

[0008] FIG. 1 is a diagram showing the configuration of an energy harvesting device according to one embodiment of the present invention. FIG. 2 is a diagram showing the structure of the antenna section of an RF energy conversion unit according to one embodiment of the present invention. FIG. 3 is a diagram showing the circuit structure of an RF-DC rectifier circuit section according to one embodiment of the present invention. Figure 4 is a graph showing the voltage output from an RF-DC rectifier circuit according to one embodiment of the present invention. FIG. 5 is a flowchart showing an energy harvesting process according to one embodiment of the present invention. Specific details for implementing the invention

[0009] Throughout the specification, identical reference numbers denote substantially identical components. In the following description, detailed descriptions of components and functions known in the art may be omitted if they are not related to the core components of the invention. The meanings of the terms described in this specification should be understood as follows.

[0010] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims.

[0011] The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining embodiments of the present invention are exemplary, and therefore the present invention is not limited to the depicted details. Throughout the specification, the same reference numerals refer to the same components. Furthermore, in describing the present invention, if it is determined that a detailed description of related known technology may unnecessarily obscure the essence of the present invention, such detailed description is omitted.

[0012] Where terms such as 'comprising,' 'having,' 'consisting of,' etc. are used in this specification, other parts may be added unless 'only' is used. Where a component is expressed in the singular, it includes cases where it is included in the plural unless specifically stated otherwise.

[0013] In interpreting the components, they are interpreted to include a margin of error even in the absence of a separate explicit statement.

[0014] In the case of an explanation of a temporal relationship, for example, when a temporal sequence is explained using 'after', 'following', 'next', 'before', etc., it may include cases where the sequence is not continuous unless 'immediately' or 'directly' is used.

[0015] Although terms such as "first," "second," etc. are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another. Accordingly, the first component mentioned below may be the second component within the technical scope of the present invention.

[0016] The term “at least one” should be understood to include all combinations that can be presented from one or more related items. For example, the meaning of “at least one of the first item, the second item, and the third item” may mean not only the first item, the second item, or the third item individually, but also all combinations of items that can be presented from two or more of the first item, the second item, and the third item.

[0017] The features of each of the various embodiments of the present invention may be combined or combined with one another, either partially or wholly, and may technically enable various interlocking and operation. Each embodiment may be implemented independently of one another or may be implemented together in an associated relationship.

[0019] Hereinafter, an energy harvesting device according to the present invention will be described in detail with reference to FIGS. 1 to 4. FIG. 1 is a diagram showing the configuration of an energy harvesting device according to one embodiment of the present invention, FIG. 2 is a diagram showing the structure of the antenna section of an RF energy conversion unit according to one embodiment of the present invention, and FIG. 3 is a diagram showing the circuit structure of an RF-DC rectifier circuit section according to one embodiment of the present invention. FIG. 4 is a graph showing the voltage output from the RF-DC rectifier circuit section according to one embodiment of the present invention.

[0020] An energy harvesting device (100) converts RF energy into electrical energy and outputs it. An energy harvesting device (100) according to one embodiment of the present invention includes an RF energy conversion unit (110), an energy storage unit (120), and a voltage stabilization unit (130), as shown in FIG. 1.

[0021] The RF energy conversion unit (110) collects ambient RF energy and converts the collected RF energy into electrical energy. Specifically, the RF energy conversion unit (110) collects ambient RF energy and converts the collected RF energy to output an energy harvesting current (Ceh) to the energy storage unit (120). At this time, the energy harvesting current (Ceh) output from the RF energy conversion unit (110) may contain noise because it has not passed through a separate rectifier circuit.

[0022] An RF energy conversion unit (110) according to one embodiment of the present invention includes an antenna unit (111), an impedance matching circuit unit (112), and an RF-DC rectification circuit unit (113), as shown in FIG. 1.

[0023] The antenna unit (111) collects RF energy resulting from external electromagnetic radiation from the surrounding environment and generates an antenna output voltage corresponding to the collected RF energy. At this time, the antenna output voltage is an alternating current voltage.

[0024] The antenna section (111) may include a plurality of antennas that collect RF energy of different frequencies to increase the total amount of RF energy collected. The antenna section (111) may include a plurality of antennas that collect each RF energy corresponding to a frequency band. Specifically, as shown in FIG. 2, the antenna section (111) may include a first antenna (111a) and a second antenna (111b) that collect RF energy of different frequency bands. Each antenna may have a smaller area as the frequency band being received increases. For example, the antenna section (111) may include a first antenna (111a) that collects RF energy of a 1.1 GHz frequency band and a second antenna (111b) that collects RF energy of a 1.8 GHz frequency band, and the first antenna (111a) may have a larger area than the second antenna (111b).

[0025] The impedance matching circuit (112) matches the impedance between the antenna section (111) and the RF-DC rectifier circuit (113) to improve the reception efficiency of RF energy collected by the antenna section (111).

[0026] The RF-DC rectifier circuit (113) rectifies the impedance-matched antenna output voltage and outputs an energy harvesting current (Ceh) to the energy storage unit (120). Specifically, the RF-DC rectifier circuit (113) receives a first antenna output voltage (Vao1), which is an antenna output voltage output from the antenna unit (111), and a second antenna output voltage (Vao2), which is an inverted voltage of the antenna output voltage, as inputs, rectifies them, and outputs an energy harvesting current (Ceh). For example, as shown in FIG. 3, the RF-DC rectifier circuit (113) receives the first antenna output voltage (Vao1) through the first input terminal (IN1) and receives the second antenna output voltage (Vao2) through the second input terminal (IN2), rectifies them, and outputs an energy harvesting current (Ceh).

[0027] The RF-DC rectifier circuit (113) according to an embodiment of the present invention does not include an oscillation unit including a separate clock because it receives a first antenna output voltage (Vao1), which is an antenna output voltage, and a second antenna output voltage (Vao2), which is an inverted voltage of the antenna output voltage.

[0028] An RF-DC rectifier circuit (113) according to one embodiment of the present invention rectifies an antenna output voltage using a plurality of diodes (D1, D2) and capacitors (C1, C2). Specifically, the RF-DC rectifier circuit (113) includes at least one unit rectifier circuit (URC) comprising a first diode (D1) which is an NMOS transistor, a second diode (D2) which is a PMOS transistor, a first capacitor (C1) connected to the output terminal of the first diode (D1), and a second capacitor (C2) connected to the output terminal of the second diode (D2). Accordingly, the RF-DC rectifier circuit (113) may be configured such that at least one unit rectifier circuit (URC) is linearly connected. Accordingly, the RF-DC rectifier circuit (113) rectifies a first antenna output voltage (Vao1) and a second antenna output voltage (Vao2) through at least one unit rectifier circuit (URC) to output an energy harvesting current (Ceh).

[0029] The RF-DC rectifier circuit section (113) includes a first input terminal (IN1) that receives a first antenna output voltage (Vao1), which is an antenna output voltage; a second input terminal (IN2) that receives a second antenna output voltage (Vao2), which is an inverted voltage of the antenna output voltage; and an output terminal (OUT) that outputs an energy harvesting current (Ceh) rectified by at least one unit rectifier circuit (URC) and at least one unit rectifier circuit (URC). At this time, as shown in FIG. 3, the first input terminal (IN1) is connected to the output terminal of the first diode (D1) and the input terminal of the second diode (D2) through a first capacitor (C1), and the second input terminal (IN2) is connected to the input terminal and control terminal of the first diode (D1), and is connected to the output terminal and control terminal of the second diode (D2) through a second capacitor (C2).

[0030] An RF-DC rectifier circuit (113) according to one embodiment of the present invention includes a first diode (D1) which is an NMOS transistor having a high threshold voltage and a low turn-on resistance, and a second diode (D2) which is a PMOS transistor having a low threshold voltage and a high turn-on resistance. Accordingly, as shown in FIG. 4, the RF-DC rectifier circuit (113) including the first diode (D1) which is an NMOS transistor and the second diode (D2) which is a PMOS transistor outputs a more stable voltage than a rectifier circuit composed only of NMOS transistors and outputs a higher voltage than a rectifier circuit composed only of PMOS transistors.

[0031] The energy storage unit (120) receives an energy harvesting current (Ceh) and stores power, and when the first auxiliary voltage (Va1), which is a voltage generated by the stored power, is greater than or equal to the available voltage, the first auxiliary voltage (Va1) is output to the voltage stabilization unit (130).

[0032] As the energy harvesting current (Ceh) is input to the energy storage unit (120), the amount of power stored in the energy storage unit (120) increases. Accordingly, the first auxiliary voltage (Va1) generated by the stored power rises, and when the first auxiliary voltage (Va1) is greater than or equal to the available voltage, the energy storage unit (120) outputs the first auxiliary voltage (Va1).

[0033] According to one embodiment of the present invention, the RF energy conversion unit (110) includes an RF-DC rectification circuit unit (113) and outputs a rectified energy harvesting current (Ceh), and accordingly, the energy storage unit (120) can be directly connected to the RF energy conversion unit (110). That is, since the energy storage unit (120) directly receives the unrectified energy harvesting current (Ceh) output from the RF energy conversion unit (110), the first auxiliary voltage (Va1) output from the energy storage unit (120) may contain noise, so the first auxiliary voltage (Va1) can output a stable second auxiliary voltage (Va2) with the noise removed through the voltage stabilization unit (130) described later.

[0034] The energy storage unit (120) includes a storage unit (121) that receives an energy harvesting current (Ceh) and stores power, and a switching unit (122) that outputs the first auxiliary voltage (Va1), which is a voltage generated by the stored power, to a voltage stabilization unit (130) when the first auxiliary voltage (Va1) is greater than or equal to the available voltage.

[0035] The storage unit (121) receives an energy harvesting current (Ceh) from the RF energy conversion unit (110) and stores power.

[0036] The switching unit (122) controls the storage unit (121) to output the first auxiliary voltage (Va1) to the voltage stabilization unit (130) when the first auxiliary voltage (Va1) generated by the power stored in the storage unit (121) is greater than or equal to the available voltage.

[0037] The voltage stabilizer (130) rectifies the first auxiliary voltage (Va1) output from the energy storage unit (120) and outputs a second auxiliary voltage (Va2). Specifically, since the energy storage unit (120) receives an unrectified energy harvesting current (Ceh), the first auxiliary voltage (Va1) output from the energy storage unit (120) may contain noise. Accordingly, the voltage stabilizer (130) removes the noise from the first auxiliary voltage (Va1) output from the energy storage unit (120) and outputs a second auxiliary voltage (Va2) having a stable level.

[0038] Referring again to FIG. 1, the voltage stabilization unit (130) includes a bandgap reference voltage generation unit (131) and a regulator unit (132).

[0039] The bandgap reference voltage generator (131) generates a bandgap reference voltage (Vref) that maintains a constant level even with changes in temperature and provides it to the regulator unit (132) to be described later.

[0040] The regulator unit (132) outputs a second auxiliary voltage (Va2) corresponding to a first auxiliary voltage (Va1) using a reference voltage (Vref) generated from a bandgap reference voltage generator (131). Accordingly, the voltage stabilization unit (130) according to one embodiment of the present invention can output a more stable second auxiliary voltage (Va2) with noise removed.

[0041] A voltage stabilization unit (130) according to one embodiment of the present invention includes a bandgap reference voltage generation unit (131) and a regulator unit (132) rather than a DC-DC converter including an inductor, thereby preventing power loss caused by the inductor of the DC-DC converter, and the complex analog circuits are replaced by the bandgap reference voltage generation unit (131) and the regulator unit (132), so that the circuit area of ​​the voltage stabilization unit (130) can be reduced.

[0043] Hereinafter, an energy harvesting process according to the present invention will be described in detail with reference to FIG. 5. FIG. 5 is a flowchart showing an energy harvesting process according to one embodiment of the present invention.

[0044] Steps S511 to S513 are performed by the RF energy conversion unit (110), steps S521 to S522 are performed by the energy storage unit (120), and steps S531 to S532 are performed by the voltage stabilization unit (130).

[0045] First, the energy harvesting device (100) converts RF energy corresponding to the frequency band of the antenna and outputs an antenna output voltage (S511). The energy harvesting device (100) may include multiple antennas that collect RF energy of different frequencies to increase the total amount of RF energy received.

[0046] Afterwards, the energy harvesting device (100) can improve the reception efficiency of RF energy by matching the impedance to the antenna output voltage between the antenna section (111) and the RF-DC rectifier circuit section (113) (S512).

[0047] Subsequently, the energy harvesting device (100) rectifies the antenna output voltage as described above to generate an energy harvesting current (Ceh) (S513). According to one embodiment of the present invention, the antenna output voltage is converted into an energy harvesting current (Ceh) by an RF-DC rectification circuit (113) comprising a first diode (D1), which is an NMOS transistor having a high threshold voltage and a low turn-on resistance, and a second diode (D2), which is a PMOS transistor having a low threshold voltage and a high turn-on resistance. Accordingly, the RF-DC rectification circuit (113) comprising the first diode (D1), which is an NMOS transistor, and the second diode (D2), which is a PMOS transistor, outputs a more stable voltage than a rectification circuit composed only of NMOS transistors and outputs a higher voltage than a rectification circuit composed only of PMOS transistors.

[0048] According to one embodiment of the present invention, since the RF energy conversion unit (110) includes an RF-DC rectification circuit unit (113), it outputs a rectified energy harvesting current (Ceh), and accordingly, the energy storage unit (120) can be directly connected to the RF energy conversion unit (110). That is, since the energy storage unit (120) directly receives the unrectified energy harvesting current (Ceh) output from the RF energy conversion unit (110), the first auxiliary voltage (Va1) output from the energy storage unit (120) may contain noise.

[0049] Subsequently, the energy harvesting device (100) stores the electrical energy converted by the RF energy conversion unit (110) in the energy storage unit (120) (S521). Specifically, the energy harvesting current (Ceh) converted by the RF energy conversion unit (110) is input into the energy storage unit (120), and the energy storage unit (120) stores power.

[0050] Subsequently, when the voltage generated by the energy harvesting current (Ceh) is greater than the available voltage, the energy harvesting device (100) outputs the stored electrical energy to the voltage stabilization unit (130) (S522). Specifically, when the energy harvesting current (Ceh) is input to the energy storage unit (120) and the first auxiliary voltage (Va1) generated by the stored power is greater than the available voltage, the switching unit (122) controls the storage unit (121) to output the first auxiliary voltage (Va1), so that the energy harvesting device (100) outputs the first auxiliary voltage (Va1).

[0051] Afterwards, the energy harvesting device (100) outputs a bandgap reference voltage (Vref) that maintains a constant level even with changes in temperature through the bandgap reference voltage generation unit (131) of the voltage stabilization unit (130) (S531).

[0052] Subsequently, the energy harvesting device (100) receives the bandgap reference voltage (Vref) and the first auxiliary voltage (Va1) generated from the bandgap reference voltage generator (131) through the regulator section (132) of the voltage stabilizer (130), and outputs a second auxiliary voltage (Va2) corresponding to the first auxiliary voltage (Va1) using the reference voltage (Vref) (S532). Accordingly, the energy harvesting device (100) according to one embodiment of the present invention can output a more stable second auxiliary voltage (Va2) with noise removed.

[0053] An energy harvesting device (100) according to one embodiment of the present invention includes a bandgap reference voltage generating unit (131) and a regulator unit (132) rather than a DC-DC converter including an inductor, thereby preventing power loss caused by the inductor of the DC-DC converter, and the complex analog circuits are replaced by the bandgap reference voltage generating unit (131) and the regulator unit (132), so that the circuit area of ​​the voltage stabilization unit (130) can be reduced.

[0055] Those skilled in the art to which the present invention pertains will understand that the above-described invention may be implemented in other specific forms without altering its technical concept or essential features.

[0056] Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. The scope of the invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the invention. Explanation of the symbols

[0057] 100: Energy harvesting device 110: RF energy converter 111: Antenna section 112: Impedance matching circuit section 113: RF-DC rectifier circuit 120: Energy storage unit 121: Storage unit 122: Switching unit 130: Voltage Stabilizer 131: Bandgap Reference Voltage Generator 132: Regulator section

Claims

Claim 1 delete Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 An RF energy converter that converts RF energy of different frequency bands in the surroundings to output an energy harvesting current; and an energy storage unit that receives and stores the energy harvesting current and outputs a first auxiliary voltage from the stored power; wherein the RF energy converter includes an antenna unit comprising a first antenna that collects RF energy of different frequency bands and outputs a first antenna output voltage corresponding to the first RF energy, and a second antenna that outputs a second antenna output voltage corresponding to the first RF energy; and an RF-DC rectifier circuit unit that rectifies the first and second antenna output voltages and outputs the energy harvesting current; wherein the RF-DC rectifier circuit unit includes a first unit rectifier circuit and a second unit rectifier circuit connected in series with the first unit rectifier circuit, and the first unit rectifier circuit includes a first capacitor comprising a first electrode to which the first antenna output voltage is applied and a second electrode connected to a first node; A first NMOS transistor comprising a first electrode and a gate electrode to which the second antenna output voltage is applied, and a second electrode connected to the first node; a first PMOS transistor comprising a first electrode connected to the first node, a second electrode connected to the second node, and a gate electrode; and a second capacitor comprising a first electrode to which the second antenna output voltage is applied and a second electrode connected to the second node, wherein the second unit rectifier circuit comprises: a third capacitor comprising a first electrode to which the first antenna output voltage is applied and a first electrode and a gate electrode connected to the third node; and a second NMOS transistor comprising a first electrode and a gate electrode connected to the second node and a second electrode connected to the third node.An energy harvesting device comprising a first electrode connected to the third node, a second electrode connected to the fourth node, and a gate electrode, and a second PMOS transistor that outputs the energy harvesting current to the fourth node, wherein the energy storage unit comprises: a storage unit that receives the energy harvesting current and stores power; and a switching unit that outputs the first auxiliary voltage when the first auxiliary voltage is greater than or equal to the available voltage. Claim 6 delete Claim 7 delete Claim 8 delete Claim 9 An energy harvesting device characterized by further including, in claim 5, a voltage stabilization unit that generates a reference voltage and outputs a second auxiliary voltage corresponding to the first auxiliary voltage using the reference voltage. Claim 10 An energy harvesting device according to claim 9, wherein the voltage stabilization unit comprises: a bandgap reference voltage generator that generates a reference voltage maintaining a constant level in response to temperature changes; and a regulator unit that receives the first auxiliary voltage and the reference voltage and outputs a second auxiliary voltage of a constant level corresponding to the first auxiliary voltage using the reference voltage. Claim 11 delete Claim 12 delete Claim 13 delete

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