EP3794737A1 - Collecte d'horloge de haute précision à faible puissance dans des systèmes de couplage inductif - Google Patents

Collecte d'horloge de haute précision à faible puissance dans des systèmes de couplage inductif

Info

Publication number
EP3794737A1
EP3794737A1 EP19803392.0A EP19803392A EP3794737A1 EP 3794737 A1 EP3794737 A1 EP 3794737A1 EP 19803392 A EP19803392 A EP 19803392A EP 3794737 A1 EP3794737 A1 EP 3794737A1
Authority
EP
European Patent Office
Prior art keywords
modulation switch
voltage
digital processing
processing circuit
antenna
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP19803392.0A
Other languages
German (de)
English (en)
Other versions
EP3794737A4 (fr
Inventor
Matan Hershko
Oren Goldshtein
Aharon DAFFAN
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Vectorious Medical Technologies Ltd
Original Assignee
Vectorious Medical Technologies Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US15/981,914 external-priority patent/US10205488B2/en
Application filed by Vectorious Medical Technologies Ltd filed Critical Vectorious Medical Technologies Ltd
Publication of EP3794737A1 publication Critical patent/EP3794737A1/fr
Publication of EP3794737A4 publication Critical patent/EP3794737A4/fr
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B5/00—Near-field transmission systems, e.g. inductive or capacitive transmission systems
    • H04B5/70—Near-field transmission systems, e.g. inductive or capacitive transmission systems specially adapted for specific purposes
    • H04B5/72—Near-field transmission systems, e.g. inductive or capacitive transmission systems specially adapted for specific purposes for local intradevice communication
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/0002—Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network
    • A61B5/0031—Implanted circuitry
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/021—Measuring pressure in heart or blood vessels
    • A61B5/0215—Measuring pressure in heart or blood vessels by means inserted into the body
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6846—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive
    • A61B5/6847—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive mounted on an invasive device
    • A61B5/686—Permanently implanted devices, e.g. pacemakers, other stimulators, biochips
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/80—Circuit arrangements or systems for wireless supply or distribution of electric power involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B5/00—Near-field transmission systems, e.g. inductive or capacitive transmission systems
    • H04B5/20—Near-field transmission systems, e.g. inductive or capacitive transmission systems characterised by the transmission technique; characterised by the transmission medium
    • H04B5/24—Inductive coupling
    • H04B5/26—Inductive coupling using coils
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B5/00—Near-field transmission systems, e.g. inductive or capacitive transmission systems
    • H04B5/70—Near-field transmission systems, e.g. inductive or capacitive transmission systems specially adapted for specific purposes
    • H04B5/79—Near-field transmission systems, e.g. inductive or capacitive transmission systems specially adapted for specific purposes for data transfer in combination with power transfer
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2560/00—Constructional details of operational features of apparatus; Accessories for medical measuring apparatus
    • A61B2560/02—Operational features
    • A61B2560/0204—Operational features of power management
    • A61B2560/0214—Operational features of power management of power generation or supply
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2310/00—The network for supplying or distributing electric power characterised by its spatial reach or by the load
    • H02J2310/10—The network having a local or delimited stationary reach
    • H02J2310/20—The network being internal to a load
    • H02J2310/23—The load being a medical device, a medical implant, or a life supporting device

Definitions

  • the present invention relates generally to inductive coupling clock-less systems such as medical implants, and particularly to methods and systems configured for operating by way of clock-signal harvesting.
  • Inductive coupling is used as a means for communication and for providing electrical power in various systems, such as in medical implants.
  • PCT International Publication WO 2014/170771 describes an implant including an antenna, circuitry, and a voltage clamping element.
  • the antenna is configured to communicate with an external unit using inductive coupling of a magnetic field.
  • the circuitry is configured to produce data for transmission to the external unit, to modulate a load impedance applied to the antenna as a function of the data so as to transmit the data, and to receive electrical power from the magnetic field via the antenna for powering the circuitry.
  • the voltage clamping element is coupled to clamp a voltage induced by the magnetic field across the antenna so as to maximize a modulation depth of the load impedance, and so as to regulate the electrical power that powers the circuitry.
  • An embodiment of the present invention that is described herein provides an apparatus including a front-end circuit and a digital processing circuit.
  • the front-end circuit includes an antenna and a modulation switch.
  • the digital processing circuit is configured to transmit data to a remote unit using inductive coupling of an Alternating Current (AC) magnetic field generated by the remote unit, by modulating a load impedance of the antenna using the modulation switch.
  • the front-end circuit is configured to supply to the digital processing circuit a voltage signal, which has a frequency of the AC magnetic field and which has a non-zero envelope both during intervals in which the modulation switch is closed and during intervals in which the modulation switch is open, and wherein the digital processing circuit is configured to derive a clock signal from the voltage signal.
  • the front-end circuit includes a voltage clamping element connected in series with the modulation switch. In an embodiment, the front-end circuit further includes a diode connected in series with the modulation switch. In an example embodiment, the antenna is connected in parallel to the serially-connected modulation switch and voltage clamping element.
  • the voltage clamping element is configured to clamp a voltage signal induced by the AC magnetic field across the antenna, and the front-end circuit is configured to provide the clamped voltage signal for powering the digital processing circuit from a connection point between the modulation switch and the voltage clamping element.
  • the voltage clamping element includes a transistor biased by a Zener diode.
  • the digital processing circuit is configured to derive the clock signal solely from the voltage signal without an oscillator and/or a Phase-Locked Loop (PLL).
  • the apparatus includes a pressure sensor, and the digital processing circuit is configured to read a pressure reading from the pressure sensor, and to transmit the pressure reading to the remote unit using the derived clock signal.
  • the antenna includes a coil.
  • the front-end circuit includes a capacitor connected in parallel with the coil.
  • the digital processing circuit is configured to modulate the load impedance by alternately opening and closing the modulation switch in a pattern that depends on the data.
  • the digital processing circuit is configured to derive the clock signal from the voltage signal both during the intervals in which the modulation switch is closed and during the intervals in which the modulation switch is open.
  • a method including, using a digital processing circuit, transmitting data to a remote unit using inductive coupling of an Alternating Current (AC) magnetic field generated by the remote unit, by modulating a load impedance of an antenna using a modulation switch.
  • a voltage signal which has a frequency of the AC magnetic field and which has a non-zero envelope both during intervals in which the modulation switch is closed and during intervals in which the modulation switch is open, is supplied to the digital processing circuit.
  • a clock signal is derived from the voltage signal in the digital processing circuit.
  • a method including applying an external unit to form a magnetic field, having a frequency and an accuracy, around a remote system comprising a modulation switch and a digital processing circuit.
  • a clock signal having the frequency and the accuracy, is derived in the remote system from the magnetic field.
  • the digital processing circuit is applied to generate a digital signal carrying data synchronized with the clock signal.
  • the digital processing circuit is applied to manipulate the modulation switch in a series of alternations between an open state and a closed state in a pattern derived from the digital signal, thereby encoding the data by way of load modulation.
  • the external unit is applied to decode the data by extracting the load modulation with the clock signal.
  • the method includes powering the digital processing circuit solely from the magnetic field by way of inductive coupling.
  • deriving the clock signal is performed both during intervals in which the modulation switch is in the closed state and during intervals in which the modulation switch is in the open state.
  • a voltage clamping element is connected in series with the modulation switch.
  • a diode is connected in series with the modulation switch.
  • an antenna of the remote system is connected in parallel to the serially-connected modulation switch and voltage clamping element.
  • the method includes clamping, using the voltage clamping element, a voltage signal induced by the magnetic field across the antenna, and providing the clamped voltage signal for powering the digital processing circuit from a connection point between the modulation switch and the voltage clamping element.
  • Fig. 1 is a block diagram that schematically illustrates a system (e.g., an implant) for measuring pressures (e.g., sensing blood pressure in the cardiovascular system) remotely to an external unit, in accordance with an embodiment of the present invention
  • a system e.g., an implant
  • pressures e.g., sensing blood pressure in the cardiovascular system
  • Fig. 2 is a flow chart that schematically illustrates a method for operating a system (e.g., an implant) for measuring pressures (e.g., sensing blood pressure in the cardiovascular system) remotely to an external unit, in accordance with an embodiment of the present invention
  • Fig. 3 is a block diagram that schematically illustrates an implant for sensing blood pressure in the cardiovascular system, in accordance with another embodiment of the present invention.
  • Embodiments of the present invention that are described herein provide improved methods and apparatus for clock signal harvesting in inductive-coupling systems.
  • the embodiments described herein refer mainly to devices that are implanted in the cardiovascular system, measure ambient blood pressure and communicate with an external unit.
  • the disclosed techniques are applicable in various other systems and applications.
  • a sensory implant is positioned in the cardiovascular system of a patient and communicates with an external unit using inductive coupling.
  • the external unit generates an Alternating Current (AC) magnetic field, which is used both for communication and for supplying energy to the implant.
  • the implant comprises a front-end circuit, which comprises an antenna and a modulation switch.
  • the implant further comprises a digital processing circuit that transmits blood-pressure readings and other data to the remote unit by modulating the load impedance of the antenna using the modulation‘on/off switch.
  • the digital processing circuit is clocked by a clock signal that is derived directly from the carrier of the AC magnetic field generated by the external unit.
  • the front-end circuit of the implant has a unique topology, which enables it to supply to the digital processing circuit a voltage signal, which has the same frequency as the AC magnetic field and has a non-zero envelope both during intervals in which the modulation switch is open, and during intervals in which the modulation switch is closed.
  • the digital processing circuit derives its clock signal from this voltage signal, both during the intervals in which the modulation switch is open, and during the intervals in which the modulation switch is closed. This capability is in sharp contrast to other possible inductive coupling schemes, in which the modulation switch short-circuits the antenna when closed.
  • the front-end circuit comprises a voltage clamping element that fixes the voltage and is connected in series with the modulation switch.
  • the antenna is connected in parallel to the serially-connected modulation switch and voltage clamping element.
  • Energy supply for the digital processing circuit is taken from the connection point between the modulation switch and the voltage clamping element.
  • the voltage signal from which the clock signal is extracted is taken directly from across the antenna.
  • the envelope of the voltage signal provided to the digital processing circuit retains a non-zero average value regardless of whether the modulation switch is open or closed.
  • the digital processing circuit is able to derive the clock signal directly from the voltage signal independently to operation of the modulation switch and/or clamping element.
  • the disclosed clock harvesting scheme enables the implant to derive its clock signal directly from the AC magnetic field of the external unit, without a need for any sort of local oscillator, Phase-Locked Loop (PLL) or similar components.
  • PLL Phase-Locked Loop
  • the size, cost and power consumption of the implant are reduced considerably relative to similar sensory implants equipped with any type of accurate internal clock source, and the reliability of the implant is maintained or is even improved relative thereto.
  • the clock signal in the implant tracks the frequency of the AC magnetic field directly, rather than being locked on it, the clock signal is free of additional phase noise, jitter and other possible impairments.
  • the clock accuracy of the implant is dictated directly by the clock accuracy of the external unit. Therefore, for example, in the disclosed solution the clock accuracy of the implant does not influence the implant’s energy consumption due to the fact that it is not generated internally.
  • Fig. 1 is a block diagram that schematically illustrates an apparatus in a form of an implant 20 configured for sensing blood pressure in the cardiovascular system, for example in the heart or in the pulmonary artery, in accordance with an embodiment of the present invention.
  • Implant 20 is implanted in the cardiovascular system of a patient and measures the ambient blood pressure.
  • Implant 20 communicates with a remote external unit 50, and receives energy supply from the external unit, using magnetic-field inductive coupling.
  • implant 20 comprises a capacitive Micro-Electro-Mechanical Systems (MEMS) pressure sensor 24, a digital processing circuit 28 and a front-end circuit 30.
  • Sensor 24 is applicable for measuring the ambient blood pressure by producing an output derived from change of capacitance indicative of change in ambient pressure.
  • Digital processing circuit 28 among other tasks, converts the output of sensor 24 into a digital signal sufficient/applicable for transmission.
  • the external unit generates an Alternating Current (AC) magnetic field, which is induced in an antenna coil 32 in front-end circuit 30.
  • Digital processing circuit 28 modulates the load impedance of the antenna, which in turn modulates the induced magnetic field, so as to transmit data (e.g., the sensor output) to the external unit.
  • the induced magnetic field is also used for supplying electrical power for powering digital processing circuit 28, and for supplying a clock signal for clocking digital processing circuit 28.
  • the induced magnetic field may also be used for transmitting data from the external unit to implant 20.
  • front-end circuit 30 comprises antenna coil 32, also referred to herein as“antenna” for brevity.
  • a capacitor 36 is connected in parallel with antenna coil 32, so as to form a parallel resonant circuit.
  • the resonance frequency of this resonant circuit is set to match the frequency of the magnetic field generated by the external unit.
  • the resonant circuit typically has a high Q factor, i.e., a sharp resonance curve. This feature increases the sensitivity of circuit 30.
  • Front-end circuit 30 further comprises a modulation switch 40, a voltage clamping element 44 and a diode 41 that are connected in series with one another.
  • Diode 41 rectifies the voltage induced across the antenna, so that electrical current flows only in one direction (top to bottom in the figure). With respect to the direction of current flow, diode 41 precedes switch 40, and clamping element 44 follows switch 40.
  • the cascaded (serially-connected) switch 40, voltage clamping element 44 and diode 41 are connected in parallel with antenna 32.
  • Switch 40, voltage clamping element 44 and diode 41 can be regarded collectively as a“switch circuit,” which may comprise additional components and perform additional functions.
  • Digital processing circuit 28 transmits data to the external unit by modulating switch 40 with the digital signal.
  • modulating the switch means alternately opening and closing the switch in a pattern that depends on the data.
  • Voltage clamping element 44 clamps the voltage induced by the magnetic field across antenna 32 to a suitable and accurate supply voltage for powering digital processing circuit 28.
  • voltage clamping element 44 comprises a transistor 45 that is biased by a Zener diode 46. The principles of operation of this configuration are described further below. Alternative configurations are also described.
  • the energy supply for digital processing circuit 28 (denoted“ENERGY IN”) is taken from the connection point between switch 40 and voltage clamping element 44.
  • a capacitor 42 low-pass filters the variations in energy supply occurring due to modulation of switch 40.
  • the voltage signal from which circuit 28 derives (“harvests”) a clock signal, on the other hand, is taken directly from across antenna 32.
  • digital processing circuit 28 comprises a buffer 48 that is configured to convert the voltage signal into a digital square-wave clock signal (denoted “CLK”).
  • CLK digital square-wave clock signal
  • the clock signal has nominal logic levels as specified for the digital circuitry being clocked.
  • Buffer 48 may comprise, for example, a comparator that compares the voltage signal to a threshold. If the voltage signal is below the threshold, the comparator outputs a voltage corresponding to“logic 0”. If the voltage signal is above the threshold, the comparator outputs a voltage corresponding to“logic 1”.
  • the threshold is preset, e.g., to zero.
  • circuit 28 may comprise logic that adapts the threshold, e.g., for compensating for DC offset in the voltage signal and/or for creating a more balanced clock signal with a duty cycle closer to 50%.
  • implant 20 shown in Fig. 1 is an example configuration, which is chosen purely for the sake of conceptual clarity. In alternative embodiments, any other suitable device configuration can be used. Elements of implant 20 that are not mandatory for understanding of the disclosed techniques have been omitted from the figure for the sake of clarity.
  • implant 20 may be implemented using suitable hardware, such as in one or more RFICs, microprocessors, Application-Specific Integrated Circuits (ASICs) or Field-Programmable Gate Arrays (FPGAs).
  • suitable hardware such as in one or more RFICs, microprocessors, Application-Specific Integrated Circuits (ASICs) or Field-Programmable Gate Arrays (FPGAs).
  • ASICs Application-Specific Integrated Circuits
  • FPGAs Field-Programmable Gate Arrays
  • some elements of device 20, e.g., certain functions of digital processing circuit 28, can be implemented using software, or using a combination of hardware and software elements.
  • the magnetic field generated by the external unit is typically an AC field.
  • the magnetic field is sinusoidal and has a frequency of 6.78MHz.
  • front-end circuit 30 is configured to provide the voltage signal, which is induced in antenna 32 by this magnetic field, to digital processing circuit 28.
  • the voltage signal has the frequency of the AC magnetic field generated by external unit 50.
  • Circuit 28 reconstructs, from the voltage signal, a clock signal having the same frequency.
  • the clock signal is used for clocking the digital circuitry in circuit 28.
  • front-end circuit 30 enables the front-end circuit to provide a continuous, uninterrupted clock signal to digital processing circuit 28, in spite of the modulation applied by switch 40.
  • the term“uninterrupted” means that the clock signal is provided both when the modulation switch is closed and when the modulation switch is open.
  • a graph at the top of Fig. 1 shows the voltage signal (denoted “CLOCK & DATA IN”) that is provided to circuit 28.
  • the voltage signal comprises a sinusoidal carrier having a frequency of 6.78MHz.
  • the envelope of the voltage signal alternates between two voltage levels V c l and V c 2 as a result of the modulation of switch 40 by circuit 28.
  • switch 40 When switch 40 is closed, the voltage signal is set to the lower value V c l .
  • switch 40 is open, the voltage signal is set to the higher value V c 2.
  • circuit 30 provides a continuous, uninterrupted 6.78MHz carrier to circuit 28, both during intervals in which switch 40 is closed and during intervals in which switch 40 is open.
  • Voltage clamping element 44 plays a dual role in this configuration.
  • the first role as explained above, is to prevent short-circuit across the antenna during intervals in which switch 40 is closed (i.e., to ascertain that the envelope of the voltage signal provided to circuit 28 is always non-zero).
  • the second role is to clamp and regulate the energy supply to circuit 28.
  • a graph at the bottom of Fig. 1 shows the voltage provided to digital processing circuit 28 from the connection point between switch 40 and voltage clamping element 44.
  • the supply voltage has relatively small variations between a minimal voltage V s min and a maximal voltage V s max.
  • voltage clamping element comprises a parallel regulator or stabilizer, which comprises a transistor 45 (in the present embodiment a Bipolar Junction Transistor - BJT) and a Zener diode 46.
  • modulation switch 40 When modulation switch 40 is closed, the voltage induced in antenna coil 32 falls across the collector-emitter of transistor 45, and also across diode 46. When this voltage reaches the breakdown voltage (Zener voltage) of diode 46, the diode begins to conduct. As a result, transistor 46 is switched-on, i.e., begins to conduct current between its collector and emitter.
  • voltage clamping element 44 is a relatively narrowband device having a relatively slow response. As such, voltage clamping element 44 reacts to the relatively slow modulation rate of switch 40, but not to the higher rate of the carrier frequency.
  • the former rate is typically on the order of KHz (e.g., 20KHz), whereas the latter rate is on the order of MHz (e.g., 6.78MHz).
  • the configuration of voltage clamping element 44 shown in Fig. 1 is a simplified example configuration that is depicted purely for the sake of conceptual clarity. In alternative embodiments, any other suitable configuration can be used.
  • voltage clamping elements may comprise, for example, a Zener diode, a cascade of multiple silicon diodes, Schottky diodes and/or Zener diodes, various transistor-based voltage-clamping circuits, or any other suitable implementations. Such implementations are described, for example, in U.S. Patent Application 14/766,750, cited above.
  • circuit 28 comprises logic that compensates for temporary loss of one or more clock pulses in the“CLK” signal. This mechanism, however, is in no way mandatory.
  • Fig. 2 is a flow chart that schematically illustrates a method for operating implant 20, in accordance with an embodiment of the present invention. The method begins with front-end circuit 30 of implant 20 receiving the inductive coupling signal from the external unit, at an induction step 60.
  • digital processing circuit 28 modulates data, for transmission to the external unit, onto the inductive coupling signal by modulating switch 40.
  • digital processing circuit 28 receives electrical power from the connection point between modulation switch 40 and voltage clamping element 44.
  • buffer 48 buffers the“CLOCK & DATA IN” voltage signal.
  • digital processing circuit 28 receives and uses the CLK signal from the output of buffer 48. In some embodiments, digital processing circuit 28 may also demodulate data sent from the external unit over this signal.
  • Fig. 3 is a block diagram that schematically illustrates an implant for sensing blood pressure in the cardiovascular system, in accordance with another embodiment of the present invention.
  • the implant of Fig. 3 comprises an antenna 134, configured to, by drawing energy from the magnetic field generated by the external unit, provide a main supply voltage.
  • the implant further comprises a capacitive pressure sensor 122, configured to vary its capacitance in response to the ambient pressure within the cardiovascular system.
  • a voltage regulator 146 In response to control signals 148 from a logic processing unit (LPU) 140, a voltage regulator 146 converts a high voltage supply, which is derived from the main supply voltage, into a direct current (DC) sensor-supply voltage, which supplies sensor 122.
  • Voltage regulator 146 requires a certain minimum supply voltage in order to effectively supply voltage to the sensor. For example, in some embodiments, voltage regulator 46 requires at least 15.5 V. (Since this threshold is relatively high, relative to respective voltages required by other components of the implant, the voltage regulator supply voltage is referred to as a high voltage supply.) Voltage regulator 146 and sensor 122 may be collectively referred to as“operational circuitry.”
  • the implant further comprises modulating circuitry that modulates the load of antenna 134.
  • the modulating circuitry may comprise an input-selecting-and-converting unit 136, LPU 140, and a modulation switch 142.
  • input-selecting-and-converting unit 136 comprises conversion circuitry, which generates an output having a property that is a function of the capacitance that is input to the circuitry.
  • the conversion circuitry may comprise a capacitance-to-frequency converter 144.
  • Converter 144 is an oscillator whose oscillation frequency depends on the capacitance that is input to the converter, such that the converter outputs a“sensor clock out” clock signal whose frequency is a function of the input. Stated differently, converter 144 converts the input capacitance into an output frequency.
  • Input-selecting-and-converting unit 136 further comprises an analog selector 172 that is configured to, in response to control signals 170 delivered over control lines from LPU 140, select an input to converter 144.
  • Fig. 2 shows several possible inputs, as follows:
  • the capacitance of sensor 122 may be input to converter 144, such that converter 144 converts the capacitance of the sensor into the output frequency.
  • the capacitance of a reference capacitor 126 may be input to converter 144, such that the converter converts the capacitance of the reference capacitor into the output frequency.
  • the capacitance of one or more calibration capacitors“Cref” may be input to converter 144, such that the converter converts the capacitance of the reference capacitor(s) into the output frequency.
  • LPU 140 modulates the load of the antenna, by alternatingly connecting current-drawing circuitry to, and disconnecting the current-drawing circuitry from, the main supply voltage.
  • the load of the antenna is increased.
  • the load of the antenna is decreased.
  • the modulation in the load of the antenna causes variations in the amount of energy from the magnetic field consumed by the implant.
  • LPU 140 may modulate the load of the antenna such as to indicate to the external unit the capacitance of - and hence, the pressure sensed by - sensor 122.
  • the modulation in the load of the antenna also cause the main supply voltage to vary between a first, higher value, and a second, lower value. That is, when the current-drawing circuitry is disconnected from the main supply voltage, the main supply voltage has the first, higher value; conversely, when the current-drawing circuitry is connected to the main supply voltage, the main supply voltage has the second, lower value.
  • the current-drawing circuitry comprises at least part of the modulating circuitry.
  • the modulating circuitry modulates the load of the antenna by alternatingly connecting the modulating circuitry to, and disconnecting the modulating circuitry from, the main supply voltage.
  • LPU 140 modulates the load of the antenna by controlling a modulation switch 142.
  • LPU 140 increases the load of the antenna by connecting the LPU (and/or the input-selecting-and-converting unit) to the main supply voltage; conversely, by opening the switch, LPU 140 decreases the load of the antenna by disconnecting the LPU (and/or the input-selecting-and-converting unit) from the main supply voltage.
  • a diode denoted Dextl detects the envelope, thus deriving, the main supply voltage from the voltage across the antenna.
  • the threshold supply voltage for the voltage regulator is assumed to be approximately 15.5 V, and correspondingly, the amplitude of the voltage across the antenna varies between approximately 3.5 V and 20 V. Due to a small voltage drop across diode Dextl, the amplitude of the main supply voltage varies between approximately 3 V and 19.5 V.
  • the circuitry within the implant further comprises a backup voltage source, such as a capacitor Cext3.
  • a backup voltage source such as a capacitor Cext3.
  • the backup voltage source derives a backup voltage from the main supply voltage.
  • Cext3 may derive the backup voltage, by charging.
  • the backup voltage source supplies the backup voltage to the voltage regulator.
  • the voltage across the antenna would need to be significantly higher.
  • the voltage across the antenna when loaded with the current-drawing circuitry would need to be approximately 20 V, and hence, the voltage across the antenna when unloaded might need to be approximately 40 V.
  • the voltage across the antenna when unloaded is approximately 20 V.
  • the antenna would need to be supplied with a large amount of energy.
  • the placement of the modulation switch as shown herein is advantageous, in that (i) the voltage across the antenna may be relatively low (e.g., less than 22 V, such as approximately 20 V, as shown in Fig. 3B) when the current-drawing circuitry is disconnected from the main supply voltage, and/or (ii) when the current-drawing circuitry is connected to the main supply voltage, a much lower voltage - e.g., less than 5 V, such as approximately 3 V, as shown in Fig. 3B - may be supplied to the LPU.
  • the voltage across the antenna may be relatively low (e.g., less than 22 V, such as approximately 20 V, as shown in Fig. 3B) when the current-drawing circuitry is disconnected from the main supply voltage, and/or (ii) when the current-drawing circuitry is connected to the main supply voltage, a much lower voltage - e.g., less than 5 V, such as approximately 3 V, as shown in Fig. 3B - may be supplied to the LPU.
  • apparatus and techniques described herein may be applied to any alternative form of operational circuitry, any alternative form of modulating circuitry, and/or any alternative form of current-drawing circuitry.
  • the scope of the present disclosure is not limited to the particular embodiments described herein, but rather, includes any relevant application in which there is a need to power both a relatively-high-voltage consumer (referred to herein as operational circuitry) and a lower-voltage-but-relatively-high-current consumer (referred to herein as current-drawing circuitry), while achieving sufficient antenna- modulation depth.
  • sensor 122 as a capacitive pressure sensor
  • the principles described herein may be applied to operational circuitry that comprises any type of sensor that is configured to sense any type of parameter.
  • the principles described herein may be applied to a sensor that is implanted in some portion of the anatomy other than the heart, to a sensor that is not implanted at all, as well as to operational circuitry that does not include a sensor at all.
  • Embodiments of the present invention also facilitate the operation of the current-drawing circuitry, even while the current-drawing circuitry is disconnected from the main supply voltage.
  • the LPU may operate on a DC voltage Vcc that is supplied by a low drop-off regulator (LDO) 138, which rectifies and regulates the main supply voltage.
  • LDO low drop-off regulator
  • switch 142 When switch 142 is open, LDO 138 is disconnected from the main supply voltage.
  • a second backup voltage source derives a second backup voltage from the main supply voltage, and, while the switch is open, supplies the second backup voltage to the LDO.
  • LDO 138 is analogous to voltage regulator 146, while the second backup voltage source - e.g., Cextl - is analogous to the first backup voltage source - e.g., Cext3.
  • the first backup voltage source supplies the voltage regulator, and while the switch is open, the second backup voltage source supplies the LDO.
  • scope of the present disclosure includes the use of a backup voltage source for supplying voltage to the operational circuitry, as described above, even without the use of a backup voltage source for supplying voltage to the current-drawing circuitry.
  • scope of the present disclosure includes the use of a backup voltage source for supplying voltage to the current-drawing circuitry, as described above, even without the use of a backup voltage source for supplying voltage to the operational circuitry.
  • the implant further comprises a voltage clamping element 150, as explained above with respect to Fig. 1.
  • Voltage clamping element 150 is drawn in Fig. 3 as a Zener diode purely for the sake of clarity.
  • Element 150 may comprise any suitable kind of voltage clamping element, such as, for example, the element 44 of fig. 1 above.
  • LPU 140 may draw varying amounts of current, depending on the current mode of operation of the LPU.
  • the second value of the main supply voltage would vary, depending on the current mode of operation of the LPU.
  • the voltage clamping element draws an amount of current that varies inversely with the amount of current drawn by the LPU, such that, for example, the total amount of current drawn by the LPU and voltage clamping element together, while the switch is closed, is constant.
  • FIG. 3 Various other components of the implant 24 are shown in Fig. 3, as follows:
  • a diode Dext2 inhibits the discharging of Cext3, except for the purpose of supplying the voltage regulator.
  • a diode DZextl provides overvoltage protection.
  • a capacitor Cext2 filters out noise from the voltage Vcc.
  • a capacitor Cext4 stabilizes the DC voltage supplied to the sensor.
  • A“main clock/data in” signal which is derived from the raw signal received from the external unit, provides a clock signal to the LPU, and further communicates data from the external unit. For example, via the“data in” signal, the external unit may request particular information from the LPU, which the LPU then provides, e.g., by selecting the appropriate input to capacitance-to-frequency converter 144, and then modulating the load of the antenna in response to the“sensor clock out” signal, as described above.
  • The“main clock/data in” signal passes through a buffer 156, which adjusts the voltage of the signal to a level that is appropriate for the LPU.
  • a programmable resonance capacitor array 158 (depicted in Fig. 3, for simplicity, by only one capacitor) tunes the resonance capacitor in antenna 134, in response to signals 160.
  • a buffer 152 adjusts the voltage of the switch-controlling signal from the LPU to a level that is appropriate for switch 142.
  • a comparator 154 provides an indication to the LPU in the event that the voltage supply to voltage regulator 146 is not high enough. In response to the indication, the LPU communicates a signal to the external unit.
  • the methods and systems described herein can also be used in other devices and applications, such as in ultra-small actuators in medical devices, in built-in pressure sensors that evaluate the tension and fatigue in aircraft wings, bridges and other structures, in wireless pressure sensors for tires, and/or in remote temperature sensors for engines and various other machines, to name just a few possible examples.

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  • Heart & Thoracic Surgery (AREA)
  • Surgery (AREA)
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Abstract

L'invention concerne un appareil (20) comprenant un circuit frontal (30) et un circuit de traitement numérique (28). Le circuit frontal comprend une antenne (32) et un commutateur de modulation (40). Le circuit de traitement numérique est configuré pour transmettre des données à une unité à distance (50) À l'aide d'un couplage inductif d'un champ magnétique à courant alternatif (CA) généré par l'unité à distance, par modulation d'une impédance de charge de l'antenne à l'aide du commutateur de modulation. Le circuit frontal est configuré pour fournir au circuit de traitement numérique un signal de tension, comprenant une fréquence du champ magnétique alternatif et comprenant une enveloppe non nulle à la fois pendant des intervalles dans lesquels le commutateur de modulation est fermé et pendant des intervalles dans lesquels le commutateur de modulation est ouvert, et le circuit de traitement numérique étant configuré pour dériver un signal d'horloge à partir du signal de tension.
EP19803392.0A 2018-05-17 2019-04-10 Collecte d'horloge de haute précision à faible puissance dans des systèmes de couplage inductif Pending EP3794737A4 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US15/981,914 US10205488B2 (en) 2013-04-18 2018-05-17 Low-power high-accuracy clock harvesting in inductive coupling systems
PCT/IB2019/052940 WO2019220232A1 (fr) 2018-05-17 2019-04-10 Collecte d'horloge de haute précision à faible puissance dans des systèmes de couplage inductif

Publications (2)

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EP3794737A1 true EP3794737A1 (fr) 2021-03-24
EP3794737A4 EP3794737A4 (fr) 2022-03-02

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EP19803392.0A Pending EP3794737A4 (fr) 2018-05-17 2019-04-10 Collecte d'horloge de haute précision à faible puissance dans des systèmes de couplage inductif

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WO (1) WO2019220232A1 (fr)

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2776865B1 (fr) * 1998-03-31 2000-05-05 Commissariat Energie Atomique Dispositif de teletransmission par couplage inductif
FR2900752B1 (fr) * 2006-05-05 2008-10-10 Inside Contactless Sa Procede et dispositif de transmission de donnees par modulation de charge
US7787836B2 (en) * 2007-03-12 2010-08-31 Intel Corporation Multiple radios communication device and a method thereof
US8406358B1 (en) * 2008-02-14 2013-03-26 Marvell International Ltd. Radio-frequency apparatus with programmable performance and associated methods
EP2986252B1 (fr) * 2013-04-18 2018-07-25 Vectorious Medical Technologies Ltd. Implant sensoriel alimenté à distance
US11206988B2 (en) * 2015-12-30 2021-12-28 Vectorious Medical Technologies Ltd. Power-efficient pressure-sensor implant

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WO2019220232A1 (fr) 2019-11-21
EP3794737A4 (fr) 2022-03-02

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