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`(12)
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`EP 2 520 330 A1
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`(11)
`
`EUROPEAN PATENT APPLICATION
`
`(43) Date of publication:
`07.11.2012 Bulletin 2012/45
`
`(21) Application number: 12178943.2
`
`(22) Date of filing: 02.06.2003
`
`(84) Designated Contracting States:
`AT BE BG CH CY CZ DE DK EE ES FI FR GB GR
`HU IE IT LI LU MC NL PT RO SE SI SK TR
`
`(30) Priority: 31.05.2002 US 384948 P
`
`(62) Document number(s) of the earlier application(s) in
`accordance with Art. 76 EPC:
`03756088.5 / 1 509 282
`
`(71) Applicant: Med-El Elektromedizinische Geräte
`GmbH
`6020 Innsbruck (AT)
`
`(54)
`
`Low power signal transmission
`
`(57)
`A low-power implant system. The system in-
`cludes an implant for implantation into a person, such as
`a cochlear implant or a middle ear implant. The implant
`is capable of communicating with a device via transmis-
`sion of ultra wideband pulses. The device may be adapt-
`
`(51) Int Cl.:
`A61N1/372(2006.01)
`
`(72) Inventors:
`• Hochmair, Erwin
`6094 Axams (AT)
`• Hochmair, Ingeborg
`6094 Axams (AT)
`
`(74) Representative: Lucke, Andreas
`Boehmert & Boehmert
`Pettenkoferstrasse 20-22
`80336 München (DE)
`
`Remarks:
`This application was filed on 02-08-2012 as a
`divisional application to the application mentioned
`under INID code 62.
`
`ed to be worn external to the person, or may be a second
`implant. So as to conserve battery power, the transmitted
`ultra wideband pulses may have a low duty cycle of ap-
`proximately 1/1000 or less. Power savings may also be
`realized by using time-gating amplifiers in the implant
`and/or device receiver.
`
`Printed by Jouve, 75001 PARIS (FR)
`
`EP2 520 330A1
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`Description
`
`Technical Field
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`[0001] The present invention relates to low power signal transmission over short distances, which may be used, for
`example, in implanted devices such as a cochlear implant.
`
`Background Art
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`[0002] With implanted devices it may be necessary to transmit information to the implant over a comparatively short
`distance during an extended period of time.
`[0003] An example for such an application is the transmission of speech information to a fully implanted cochlear
`implant 101 from an external device 102, such as a microphone 103 and/or a processor 104 placed behind the ear or
`in the ear canal, as shown in Fig. 1. Since the transmitter 105, as well as the receiver 106, are powered from small
`batteries 107 and 108 contained in the external device 102 and in the implant 101, respectively, both the power con-
`sumption of the transmitter 105 as well as of the receiver 106 become limiting factors.
`[0004] Another application could be the transfer of information between bilateral ear level microphones and/or proc-
`essors used with hearing aid or cochlear implant applications. In these cases a comparison or a common processing of
`left and right speech signals may be necessary either for beamforming or for coordinated processing schemes in order
`not to distort direction information.
`[0005] Referring to Fig. 1, a cochlear implant transmission system typically includes an Radio Frequency (RF) trans-
`mitter 105 that drives an external coil 109 with a modulated RF signal. This signal is picked up by a receiver’s 106
`implanted coil 110, which may be located at only a few mm or cm from the transmitter coil 109, and further processed
`by the receiver 106. With conventional narrow band RF transmission schemes using well known modulation methods
`for transmission of speech signals of considerable dynamic range (e.g. 70 - 90 dB) either as an analog signal or a coded
`signal (e.g. PCM or encoded in a Σ∆-modulator-data stream, typical band width 1 ... 2 MHz), the power consumed either
`by the transmitter 105 or by the receiver 106 (e.g. when using a very low power transmitter delivering a very faint signal
`making a large RF amplification necessary), or both, may turn out to be prohibitive. Note that the overwhelming percentage
`of the total power consumption results from the RF components at the transmitting and/or receiving end. The power
`consumption of processing in the baseband is negligible due to the low speed power product of modem CMOS technology
`and the comparative low frequencies of the baseband.
`[0006] Very low power receivers may utilize, for example, diode rectifiers. However, the threshold voltage of the diode
`rectifier may be too large, even when using backward diodes for demodulation. Another very low power receiver is the
`superregenerative receiver, which does not have sufficient bandwidth for transmission of coded speech signals. Examples
`of still other receivers include superheterodyne or the homodyne receivers, or a straight amplifier chain preceding a
`demodulator. However, in each of these cases the power consumption of the RF amplification is non-negligible. De-
`pending on the transmitter power selected, the relative proportion of transmitter power to receiver power may be adapted
`to the respective battery capacity available. For example, a strong transmitted signal may require small or even no
`amplification at the receiver. However, total power consumption may be too large in any event.
`
`Summary of the Invention
`
`[0007]
`In a first embodiment of the invention there is provided a method and system for a low-power implant system.
`An implant, for implantation into a person, is capable of communicating via transmission of ultra wideband pulses. A
`device is capable of communicating with the implant via ultra wideband pulse transmission.
`[0008]
`In related embodiments, the implant and the device are capable of one of unidirectional and bidirectional
`communication via ultra wideband pulse transmission.
`[0009] The implant may be a cochlear implant or a middle ear implant. The device may be adapted to be worn external
`to the person, and include: a signal processor for processing an acoustic signal; and a transmitter capable of transmitting
`the pulses representative of the acoustic signal through the skin of the person to the implant. The implant may include
`at least one electrode and be capable of providing electrical stimulation via the at least one electrode as a function of
`the acoustic signal received from the transmitter. The device may be a second implant for implantation into the person.
`The implant and the device may communicate via ultra wideband pulses having: a duty cycle of approximately 1/1000
`or less; a time duration of between .5 ns and 10ns; and/or a pulse repetition time between 5 and 100 Ps.
`[0010]
`In still other related embodiments of the invention, the device includes one of a transmitter capable of transmitting
`ultra wideband pulses and a receiver capable of receiving ultra wideband pulses, and the implant includes the other of
`the transmitter and the receiver.
`[0011] The receiver may include a time-gated amplifier, the amplifier for amplifying the pulses received from the
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`transmitter. The time-gated amplifier may be turned on when a probability of receiving a pulse from the transmitter is
`greater than zero. The time-gated amplifier may be biased so as not to be completely off when a probability of receiving
`a pulse from the transmitter is zero. The time-gated amplifier may turn on periodically for a time duration D, the turning
`on of the amplifier synchronized with possible receipt of a pulse from the transmitter. The time-gated amplifier may
`include a controller for synchronizing turning on of the amplifier during possible receipt of a pulse from the transmitter.
`The controller may synchronize the gated amplifier with pulses received from the transmitter based on receipt of a pulse
`with a predefined amplitude and/or duration. The amplifier may be a differential amplifer or a pseudo-differential amplifier.
`The receiver may be a passive receiver. The transmitter and receiver may each include a coil or loop for transmission
`between the transmitter and the receiver via inductive coupling. The receiver may include a nonlinear electronic com-
`ponent for converting RF components, transmitted via ultra wideband pulses, back to baseband. The transmitter may
`directly transmit, via ultra wideband pulses, a baseband signal. The transmitter may transmit ultra wideband monocycle
`pulses, thus eliminating low-frequency spectral components. Due to resonances of the transmitter and/or receiver antenna
`coils certain high frequency components of the signal may become emphasized, thus producing damped RF bursts from
`each wideband pulse.
`[0012]
`In another embodiment of the invention, a method and system for a low-power hearing system includes a first
`external signal processor for providing information to one of a hearing aid and an implant. A second external signal
`processor is capable of communicating with the first external signal processor via ultra wideband pulses.
`[0013]
`In related embodiments of the invention, the ultra wideband pulses may have: a duty cycle of 1/1000 or less;
`have a time duration of between 5 ns and 10 ns; and/or have a pulse repetition time between 5 and 100 Ps. The first
`external processor and/or the second external processor may have a receiver for receiving the ultra-wideband pulses,
`the receiver including a time-gated amplifier. The time-gated amplifier may include a controller for synchronizing turning
`on of the receiver with possible receipt of a ultra wideband pulse. The controller may synchronize the gated amplifier
`with pulses received based on receipt of a pulse with a predefined amplitude or duration.
`[0014]
`In still another related embodiment, the first external signal processor may include a first microphone, and the
`second external signal processor include a second microphone. The first signal processor processes an acoustic signal
`present in a first ear of a user and the second signal processor processes an acoustic signal present in the second ear
`of the user.
`
`Brief Description of the Drawings
`
`[0015] The foregoing features of the invention will be more readily understood by reference to the following detailed
`description, taken with reference to the accompanying drawings, in which:
`
`Fig. 1 is a schematic diagram of a prior art system for transmitting acoustic information to a fully implantable cochlear
`implant from a signal processor placed behind the ear;
`Fig. 2 is a schematic diagram of a low-power implant system that includes transmission of UWB pulses, in accordance
`with one embodiment of the invention;
`Fig. 3 is a schematic diagram of a low-power implant system that includes transmission of UWB monocycle pulses,
`in accordance with one embodiment of the invention;
`Fig. 4 is a schematic diagram of a low-power implant system that includes low Q resonance, in accordance with
`one embodiment of the invention;
`Fig. 5 is a schematic diagram of a low-power implant system that includes an active receiver, in accordance with
`one embodiment of the invention;
`Fig. 6 shows a timing diagram detailing the timing of a gated receiver of a low-power implant system, in accordance
`with one embodiment of the invention;
`Fig. 7 shows a timing diagram detailing synchronization timing of a gated receiver of a low-power implant system,
`in accordance with one embodiment of the invention;
`Fig. 8 is a schematic diagram of a gated amplifier for a low-power implant system, in accordance with one embodiment
`of the invention;
`Fig. 9 is a timing diagram detailing the timing associated with the gated amplifier depicted in Fig. 8, in accordance
`with one embodiment of the invention;
`Fig. 10 is a schematic diagram of a gated amplifier for a low-power implant system that receives monocycle pulses,
`in accordance with one embodiment of the invention;
`Fig. 11 is a schematic diagram of a rectifier for a gated amplifier, in accordance with one embodiment of the invention;
`Fig. 12 is a schematic diagram of a low-power implant system that includes duplex transmission, in accordance with
`one embodiment of the invention; and
`Fig. 13 is a timing diagram detailing the timing of the low-power implant system of Fig. 12, in accordance with one
`embodiment of the invention.
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`Detailed Description of Specific Embodiments
`
`EP 2 520 330 A1
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`[0016]
`In illustrative embodiments of the invention, a system and method for low power signal transmission between,
`for example, parts of a hearing system, is presented. The low power signal transmission is achieved by transmitting very
`short ultra wideband (UWB) pulses. In various embodiments, the transmitted UWB signals are representative of signals
`having a bandwidth not exceeding 1 or 2 MHz. The UWB pulses can thus be transmitted at a very small duty cycle,
`resulting in very low transmitter power consumption. Additional power savings are realized at the receiver by using
`passive receivers or gated receivers which are synchronized to the incoming UWB pulses. Details of illustrative embod-
`iments are discussed below.
`[0017] Ultra Wideband (UWB) technology is a relatively new communication technology that is fundamentally different
`from communication using modulated methodologies. See for example, U.S. Pat. No. 6,031,862, entitled "Ultra-wideband
`Communication System and Method," which is herein incorporated by reference. Rather than employing a carrier signal,
`UWB emissions are composed of a series of short, intermittent pulses having a pulse duration on the order of picoseconds
`or nanoseconds. By varying the pulses’ amplitude, polarity, timing and/or other characteristic, information is coded into
`the data stream. Various other terms have been used for the UWB transmission mode--carrierless, baseband, nonsi-
`nusoidal and impulse-based among them.
`[0018] However, UWB has traditionally been used at high data transmission rates. For example, UWB radios typically
`perform at well over 100Mbps. Because UWB pulses are so short, high data rates can be achieved by spacing the pulses
`close together.
`[0019] Fig. 2 is a schematic diagram of a low-power implant system 200 that includes transmission of UWB pulses,
`in accordance with one embodiment of the invention. The low-power implant system includes an implant 202 for implan-
`tation into a person. The implant 202 may be, without limitation, a cochlear implant, a brainstem implant, or a middle
`ear implant. Additionally, the low-power implant system 200 includes a device 201 capable of communicating with the
`implantable portion 202 via transmission of UWB pulses. The device may be may adapted to be worn external to the
`person, such as a signal processor for processing acoustic signals. Or the external device may be a more distant device
`relative to the person, such as an FM sound amplification device or a TV set. In still other embodiments, the device 201
`may be another implant. Communication may be bi-directional, or uni-directional in either direction.
`[0020] The device 201 includes a timing circuit 211 that triggers a pulse generator 203. The pulse generator 203
`generates a UWB pulse that is transmitted via a transmitter 204 to the implant 202. The implant 202 includes a receiver
`210 for receiving the transmitted UWB pulse. Both the transmitter 204 and receiver 210 may include a coil or loop 205
`and 206, respectively, such that pulse transmission between the transmitter 204 and the receiver 210 is via inductive
`coupling. In other embodiments, transmission may be via electric dipoles, however their use may prove to be problematic
`with regard to body tissue in close proximity to the implant 202.
`[0021] As described above, the implant may be a cochlear implant (inner ear prostheses), in accordance with one
`embodiment of the invention. Cochlear implants are a means to help profoundly deaf or severely hearing impaired
`persons. Unlike conventional hearing aids, which just apply an amplified and modified sound signal, a cochlear implant
`is based on direct electrical stimulation of the acoustic nerve. The intention of a cochlear implant is to stimulate nervous
`structures in the inner ear electrically in such a way that hearing impressions most similar to normal hearing are obtained.
`[0022] The cochlear implant system essentially consists of two parts, an external device which acts as the speech
`processor and the implant which acts as a stimulator. The speech processor receives and performs signal processing
`on an acoustic signal. The processed acoustic signal is then transmitted to and received by the implant. The implant
`generates the stimulation patterns and conducts them to the nervous tissue by means of an electrode array 111 (see
`Fig. 1) which usually is positioned in the scala tympani in the inner ear.
`[0023] The processed acoustic signal transmitted is typically digitized/coded using, for example, Σ-∆ modulation (other
`embodiments may use more complex signal coding, such as Pulse Code Modulation, and also differentiate between
`pulses carrying signal information and pulses transmitted for synchronization only), and may have a bandwidth of ap-
`proximately 1-2 MHz (in certain embodiments, only signal-amplitude-derived control signals are transferred, allowing
`for a bandwidth not exceeding a few kHz). This baseband signal may be used to directly drive the transmitter 204 so as
`to transmit single-phase baseband UWB pulses, as shown in Fig. 2.
`[0024] Due to the low data rate, the resulting UWB pulses are transmitted at a very low duty cycle. Consequently, the
`transmitter 204 components consume relatively little power. The pulses received at the receiver 210 are detected,
`possibly amplified, and can be processed by conventional digital CMOS circuitry. A threshold to eliminate low level
`interference signal can be obtained, for example, by proper biasing of CMOS gates or by the use of a Schmitt-trigger circuit.
`[0025]
`In various embodiments, the simple baseband detection scheme described above is replaced by more complex
`schemes using for example, nonlinear element(s) with pre and/or post rectification amplifiers. For example, Fig. 3 is a
`schematic diagram of a low-power implant system 200 that includes transmission of UWB monocycle pulses. These
`pulses are advantageous as they do not contain low-frequency spectral components. Low-frequency spectral compo-
`nents are inefficiently transmitted via antennas and cause substantial ringing. A non-linear element 305 rectifies and
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`generates the base-band pulse from the RF signal, such as, without limitation, a diode, a backward diode, or a Schottky-
`diode.
`[0026] The coils/loops of the transmitter 204 and receiver 210 together with additional capacitance 405 or with stray
`capacitance may be utilized to provide a comparatively low Q resonance, as shown in Fig. 4, in accordance with one
`embodiment of the invention. The low Q resonance can be used to enhance receiver input signals and thus improve
`transmission. Care must be taken to not unduly prolong transmission pulses. This could lead to a reduction in data rate
`and power savings when certain types of receivers are implemented.
`[0027]
`In various embodiments of the invention, a passive receiver can be utilized. The output pulses are further
`processed by digital CMOS-logic, including a trigger circuit to establish a reasonable threshold. Although passive re-
`ceivers are easy to implement, a passive receiver is relatively insensitive, and can be utilized only for distances within
`the range of, for example, several centimeters. For larger distances, the passive receiver requires that sufficient pulse
`amplitudes are generated by the UWB transmitter. Therefore, when only very low transmitter power is available and/or
`for greater distances, the receiver must be more sensitive. This can be achieved by a wideband-amplifier preceeding
`the detector. However, such an amplifier uses a disproportionately large supply of current. The resulting power con-
`sumption may well dominate the power consumption of the whole system.
`[0028] Fig. 5 is a schematic diagram of a receiver that utilizes an amplifier(s) to advantageously increase receiver
`sensitivity, in accordance with one embodiment of the invention. An amplifier 509 may precede rectifier 305 (if needed).
`Alternatively, or in combination with amplifier 509, an amplifier 510 may follow rectifier 305.
`[0029] To conserve power, the amplifier(s) 509 and/or 510 are time-gated so as to switch the amplifier(s) on only
`during short intervals when the likelihood for reception of a signal pulse is not zero. Unlike traditional gating of receivers,
`which is done to improve signal to noise ration and to block echoes arriving later than the direct signal, the emphasis
`here is to conserve power at the receiver. Gating of the amplifiers 509 and/or 510 may be accomplished by a controller
`511, which provides an amplifier turn-on pulse that is synchronized with the transmitted signal pulses.
`[0030] Fig. 6 is an exemplary timing diagram that illustrates the timing relationships between the data to be transmitted
`601, the transmitted signals 602, the amplifier turn-on pulse 603 generated by the controller 511, and the receiver output
`signals 604. The transmitted signals are transmitted at a rate 1/T, with a pulse transmitted depending on whether the
`data to be transmitted is a logic 1 or 0. The amplifier turn-on pulses are synchronized with the possible receipt of pulses
`transmitted by the transmitter. A transmitted pulse received during activation of a turn-on pulse will be detected and
`seen at the receiver output 604, while pulses received while the turn-on pulse is inactive have no effect on receiver
`output 604.
`[0031] A timing diagram detailing synchronization of the amplifier turn-on pulse 701 with possible receipt of transmitter
`pulses 700 is shown in Fig. 7, in accordance with one embodiment of the invention. Initially, the amplifier turn-on pulses
`701 are activated at a periodic rate of 1/T, with each turn on-pulse 701 having a time duration d. At the beginning of a
`transmission, the transmitter transmits a pulse having duration slightly longer than T. The receiver receive at least a part
`of this long pulse while the turn-on pulse 701 is activated, and will recognize that a pulse has been received having a
`duration longer than d. This triggers the controller to keep the amplifier turn-on pulse 701 active until the end of the
`transmitted long pulse. This is the event which causes the controller to reset and synchronize the amplifier turn-pulse
`701 with the possible receipt of transmitter pulses 700. After the time T, the controller will activate the turn-on pulse 701
`so to receive the first possible signal pulse of the transmission. Once the controller has established synchronization
`between the turn-on pulse 701 and transmitted pulses 700, the controller will maintain synchronization for the duration
`of the transmission using, without limitation, a phase locked loop or a resettable timing generator, which may be syn-
`chronized by each received pulse (if no pulse is received, the controller mayl run free until synchronized by the next
`correctly received pulse). Receiver output 703 is as described above with regard to Fig. 6.
`[0032] Other synchronization methodologies may be utilized. For example, the transmitter may transmit an extra strong
`pulse which is received even when the amplifier(s) are in low power mode (i.e. when the turn-on pulse is inactive), in
`accordance with one embodiment of the invention. The extra strong pulse forces the controller to synchronize the turn-
`on pulse with possible receipt of transmitted pulses. In this embodiment, the amplifier(s) is not turned completely off
`when the turn on pulse is inactive. Instead, a small quiescent current is maintained such that the extra strong pulse can
`be recognized by the receiver.
`[0033]
`In preferred embodiments, the pre and post rectification amplifiers are differential amplifiers or pseudo-differ-
`ential amplifiers. This prevents the turn-on pulse (which is applied common mode) from reaching a predetermined pulse
`detection threshold. Although there will be some unavoidable feed through due to transistor tolerances, only transmitted
`signal pulses, which occur when the turn-on pulse is active, will be detected.
`[0034]
`In accordance with one embodiment of the invention, Figs. 8 and 9 show a schematic diagram and an associated
`timing diagram for a gated amplifier 801, respectively. CMOS-technology is used. T1 ... T3 are n-channel MOS-transistors,
`and T4 ... T6 are p-channel transistors. T1, T2, T5 and T6 form a pseudo-differential amplifier. T3 and T4 are part of the
`biasing circuitry and are used to turn on the amplifier to make the receiver receptive for the transmitted UWB pulses.
`[0035]
`"Diode-connected" transistor T3 is slightly forward biased by the small current defined by RQ and the supply
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`voltage VD. Since the gates of T1, T2 and T3 are connected; T2 and T3 see the same gate voltage and therefore carry
`the identical small quiescent dc-currents. The well known current mirror formed by T5 and T6 generates a drain current
`at T6 which ideally is equal to the drain current of T1. The quiescent output voltage is defined by the relative output
`resistances of T1 and T6. To make the amplifier more independent of transistor parameter tolerances, external resistors
`R1 and R2 may be added.
`[0036] To obtain significant amplification, larger drain currents are needed. Therefore, to turn the amplifier 801 on, a
`turn-on pulse 901 is applied to T4. The current through Rset enhances the forward biasing of T3 and consequently
`enlarges all currents to an appropriate level. Activation of the turn-on pulse without receipt of a transmitted pulse must
`result in an output voltage 903 smaller than the threshold of the decision circuit following the amplifier. However, when
`a pulse 902 is received during activation of the turn-on pulse 901, the voltage being induced in the antenna loop/coil will
`cause a change in the gate voltage of T1. This, in turn, causes a change in T1’s drain current that results in an output
`voltage 903 that is sufficient to trigger the decision circuit.
`[0037]
`In accordance with another embodiment of the invention, Figure 10 is a schematic diagram of a pseudo-
`differential amplifier for a receiver that receives monocycle pulses or short RF-bursts, as shown in Fig. 5. The receiver
`antenna loop/coil forms a low Q resonance with capacitor C1, which at least partly consists of stray capacitance. Capacitor
`C2 prevents the gate voltage of T1 from being shorted by the antenna loop. In principle the function of this circuit is
`equivalent to the circuit described in Fig 8. The main difference is that, in order to make efficient use of the RF components
`of the received spectrum, the biasing must ensure that T1 is driven in a sufficiently nonlinear part of its transfer charac-
`teristic so that some rectification of RF components is achieved. Resistors R3 and R4 connect the gates of T1 and T2 to
`T3 without disturbing the RF signal.
`[0038] Rectification of RF components may also be accomplished by the circuit shown in Fig 11, in accordance with
`one embodiment of the invention. Here, an extra diode D is used for the rectification of RF components of the received
`pulse.
`[0039] Fig 12 is a schematic diagram of an exemplary duplex low-power implant system between a first transceiver
`1200 and a second transceiver 1220, in accordance with one embodiment of the invention. Each transceiver 1200 and
`1220 includes a transmitter 1202 and 1222 and a receiver 1203 and 1223 that share the same loop/coil 1216 and 1236,
`respectively. Additionally, each transmitter 1202 and 1222 includes a clock generating circuit 1206 and 1226 and a UWB
`pulse generator 1208 and 1228, respectively; and each receiver 1203 and 1223 includes a pre-rectification amplifier
`1210 and 1230, a rectifying diode 1212 and 1232, and a post-rectification amplifier 1214 and 1234, respectively. Fig.
`13 is a timing diagram detailing the timing for the duplex transmission scheme shown in the embodiment of Fig. 12.
`[0040] Referring to Figs. 12 and 13, the first transceiver ("master") 1200 sets the timing for the transmission of signals
`in both directions. The second transceiver’s 1220 timing ("slave") can be locked to the received transmission pulses by
`controller 1230 logic generating turn-on pulses 1302 as described above, for example, with regard to Fig 7.
`[0041]
`In order to use the same inductive link for both directions, the pulses 1301 transmitted by the first transmitter
`1202 and the pulses 1303 transmitted by second transmitter 1222 are interleaved. To achieve this offset ∆ (e.g. ∆ = T/
`2) a delay circuit 1224 is introduced in the second transceiver 1220 to delay the pulses 1303 generated by second
`transmitter 1222 by T/2. Similar delay circuitry 1204 is utilized in the first transceiver 1200 to appropriately delay the
`gating (turn-on pulse) 1304 of the receiver 1203 associated with the first transceiver 1200. Since all signals are derived
`from the pulses 1301 generated by the first transmitter 1202, no controller logic for providing synchronization is needed
`in the first transceiver 1200.
`[0042] The low bandwidth of the signals transmitted to and/or from the implant allows the UWB pulses to be transmitted
`at a very low duty cycle, conserving power at the transmitter. Time-gating the amplifiers in the implant and/or device
`receiver also conserves power at the receiver. Approximate parameter ranges of a typical hearing system that includes
`communication via UWB pulses transmissions are, without limitation:
`
`Pulse duration (of transmitter UWB-pulse)
`Pulse repetition time
`"turn-on pulse" duration
`duty factor of transmission pulse
`duty factor of receiver gating delay between forward and backward
`transmission pulses in a duplex arrangement
`
`τ
`T
`d
`τ/T
`d/T
`∆
`
`1 ... 10 nsec
`1 ... 10 Psec
`5 ... 100 Psec
`approx. 1:1000
`approx. 1:100
`e.g. T/2 (see Fig 13)
`
`[0043]
`In accordance with another embodiment of the invention, a low-power hearing system may include UWB
`communication between parts external to the person. For example, data can be transferred, in a manner similar to the
`above-described embodiments, between a plurality of external devices, such as bilateral microphones and/or external
`signal processors that are positioned, for example, behind each ear or other various locations. The external device(s)
`can thus perform acoustic beamforming or other coordinated schemes. The external devices may be used, for example,
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`MED-EL v. ADVANCED BIONICS
`IPR2020-01016
`ADVANCED BIONICS EX 2009
`Page 6
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`

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`EP 2 520 330 A1
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`in conjunction with a hearing aid and/or an implant.
`[0044] Although various exemplary embodiments of the invention have been disclosed, it should be apparent to those
`skilled in the art that various changes and modifications can be made which will achieve some of the advantages of the
`invention without departing from the true scope of the invention. These and other obvious modifications are intended to
`be covered by the appended claims.
`[0045] Embodiments of the invention may relate to one or more of the following examples:
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`1. A low-power implant system comprising: an implant for implantation into a person, the implant capable of com-
`municating via transmission of ultra wideband pulses; and a device capable of communicating with the implant via
`ultra wideband pulse transmission.
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`2. The low-power implant system according to example 1, wherein the implant and the device are capable of one
`of unidirectional and bidirectional communication via ultra wideband pulse transmission.
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`5
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`10
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`15
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`3. The low-power implant system according to example 1, wherein the implant is a cochlear implant.
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`20
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`25
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`30
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`35
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`40
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`45
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`50
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`55
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`4. The low-power implant system according to example 1, wherein the implant is a middle ear implant.
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`5. The low-power implant system according to example 1, wherein the device is adapted to be worn external to the
`person, the device including a signal processor for processing an acoustic signal, and a transmitter capable of
`transmitting the pulses representative of the acoustic signal through the skin of the person to the implant.
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`6. The low-power implant system according to example 5, wherein the implant includes at least one electrode and
`is capable of providing electrical stimulat