Bandwidth equalization

Abstract

The invention relates to a probe buffer (100) for buffering measured signals of an object (11) generating or conducting these signals, comprising: a first receive buffer (110) comprising a first receive input (111) adapted for receiving a first measured signal (116) based on a first generated or conducted signal (115) of the object via a first conductive path (31) having a first bandwidth (118), and arranged for providing a first buffered signal (117) based on buffering the first measured signal; a first bandwidth adaptation unit (120) arranged for adapting the first bandwidth; a second receive buffer (130) comprising a second receive input (131) adapted for receiving a second measured signal (136) based on a second generated or conducted signal (135) of the object via a second conductive path (32) having a second bandwidth (138), and arranged for providing a second buffered signal (137) based on buffering the second measured signal; a comparison unit (150) arranged for providing a comparison signal (151) based on the comparison of the first buffered signal and the second buffered signal; and a controller (160) arranged for controlling the first bandwidth adaptation unit based on the comparison signal such that a difference between the first bandwidth and the second bandwidth is reduced.

Description

[0001] BANDWIDTH EQUALIZATION

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a medical probe buffer. The invention further relates to a medical probe. The invention further relates to a medical device. The invention further relates to a method for a medical probe.

[0004] BACKGROUND OF THE INVENTION

[0005] US2023318549 (A1 ) discloses a front-end device arranged to amplify an electric signal from an associated sensor, e.g. for amplifying an electric signal from a neural activity sensor. The front-end device has an amplifier circuit connected between its input and output terminals (Vin, Vout), wherein the amplifier circuit comprises a capacitive-coupled chopper circuit comprising a first gain element and first, second and third chopper switches arranged for operating at a chopper frequency. Further, the amplifier circuit has A) an impedance boosting auxiliary path connected to the input terminal in parallel with a first chopper switch of the CCC, wherein the impedance boosting auxiliary path comprises a pre-charging buffer, and B) a second gain element connected in a feedback path of the CCC. Such front-end device has high input impedance, and the input impedance is uncorrelated with the gain. A disadvantage of this device is that the common mode in the electric signal typically causes a degradation in the accuracy of the information distillable from the electric signal.

[0006] SUMMARY OF THE INVENTION

[0007] An object of the invention is to overcome one or more of the disadvantages mentioned above.

[0008] According to a first aspect of the invention, a medical probe buffer for buffering measured physiological signals of a human body, comprising: a first receive buffer comprising a first receive input adapted for receiving a first measured signal based on a first physiological signal of the human body via a first conductive path having a first bandwidth, and arranged for providing a first buffered signal based on buffering the first measured signal; a first bandwidth adaptation unit arranged for adapting the first bandwidth; a second receive buffer comprising a second receive input adapted for receiving a second measured signal based on a second physiological signal of the human body via a second conductive path having a second bandwidth, and arranged for providing a second buffered signal based on buffering the second measured signal; a calibration source arranged for generating a calibration signal provided to the human body for influencing the first measured signal and the second measured signal; a comparison unit arranged for providing a comparison signal based on the comparison of the first buffered signal and the second buffered signal, wherein the comparison signal carries or comprises information based on the calibration signal; and a controller arranged for controlling the first bandwidth adaptation unit based on the comparison signal, more specifically on the comparison signal carrying or comprising information based on the calibration signal, such that a difference between the first bandwidth and the second bandwidth is reduced.

[0009] The human body generates or carries physiological signals measurable by a medical probe. The physiological signal may be a bioelectrical signal, or an electrical signal associated with the human body. The human body generates or carries signals such as brain or nerve activity. The human body may also have electrical measurable properties, such as electrical skin resistance. The human body may also have electrical measurable characteristics, such as translucency measured by an electrically powered LED and an electrically powered light sensitive sensor. In all these examples electrical current may be exchanged between, or brought in close proximity of or in contact with the human body and the medical device measuring, receiving, generating, providing and / or exchanging this electricity with the use of the medical device. Patient safety is safeguarded by the IEC 60601-1 standard. One of the requirements in the standard is that the patient safety is guaranteed such as through the use of exposing the human body only to very low voltages.

[0010] The medical device typically comprises a medical probe comprising a medical probe buffer for providing an electrical buffer between the medical device and the human body. The buffer typically adapts the impedances of the signals between the rest of the medical device and the human body. The buffer typically also amplifies the signals from the human body to the rest of the medical device. The medical probe buffer further has the function to ensure that the medical device complies to the IEC 60601-1 standard.

[0011] A signal may be defined as a current or a voltage. A voltage is defined as an electrical potential difference between two points. A reference electrical potential may be provided as a reference from which the electrical difference can be measured, thus measuring the voltage. The reference electrical potential is transmitted by the medical probe buffer to the human body, and may be typically labelled ground, electrical ground, or electrical patient ground.

[0012] Conductively coupled should be interpreted as that an electrically conductive path is present between the components conductively coupled. The electrically conductive path may comprise a conductor directly conductively connecting the components. Alternatively, the electrically conductive path may comprise next to a conductor other passive or even active electrical elements, such as semiconductors.

[0013] When measuring multiple physiological signals, typically a large common mode voltage is present. This common mode voltage may interfere or hamper the measuring of these physiological signals. The common mode rejection (CMR) is typically as high as possible to increase the accuracy with which a physiological signal or physiological signals can be measured.

[0014] A bandwidth is a frequency range wherein an attenuation or an amplification of a signal is substantially equal. A frequency range has a highest frequency and a lowest frequency. Outside the bandwidth, the attenuation or the amplification is typically changing with the frequency. Bandwidth may be made visible in a Bode diagram, more specifically a Bode magnitude diagram. The bandwidth is shown as a flat section in the Bode diagram. If multiple flat sections are shown in the Bode diagram, typically the flat section with the highest magnitude is selected as the bandwidth. Outside the flat section, sloped sections may be shown in the Bode diagram. These sloped sections may have an order indicating the rate of change, such as first or higher order slope. Alternative definitions of bandwidth may be the numerical difference between the upper and lower frequencies of a band of electromagnetic radiation, especially an assigned range of radio frequencies, or electrical signal. Alternative definitions of bandwidth may be the smallest range of frequencies constituting a band within which a particular signal can be transmitted without distortion. The boundaries of the bandwidth are typically called cutoff points or cut-off frequencies having typically a magnitude difference of 3 dB, typically -3 dB, with the centre of the bandwidth.

[0015] The medical probe buffer comprises the first receive buffer. The first receive buffer comprises a first receive input. The first receive input is adapted for receiving a first measured signal based on a physiological signal of the human body. The first receive input receives the first measured signal via a first conductive path. The first conductive path has or contributes to a first bandwidth. The first receive buffer is arranged for providing a first buffered signal. The first buffered signal is based on buffering the first measured signal.

[0016] The medical probe buffer comprises a first bandwidth adaptation unit. The first bandwidth adaptation unit is arranged for adapting the first bandwidth.

[0017] The medical probe buffer comprises a second receive buffer. The second receive buffer comprises a second receive input. The second receive input is adapted for receiving a second measured signal based on a second physiological signal of the human body. The second receive input receives via a second conductive path. The second conductive path has or contributes to a second bandwidth. The second receive buffer is arranged for providing a second buffered signal. The second buffered signal is based on buffering the second measured signal.

[0018] The medical probe buffer comprises a calibration source. The calibration source is arranged for generating a calibration signal. The calibration signal may be outside the first bandwidth and / or the second bandwidth. The calibration signal may be seen as a disturbance signal for introducing a known disturbance into the measured signals for use for calibrating. The calibration signal is provided to the human body for disturbing the first measured signal and the second measured signal. The calibration signal thus has an effect on or influences the first and the second measured signals.

[0019] The medical probe buffer comprises a comparison unit. The comparison unit is arranged for providing a comparison signal. The comparison signal is based on the comparison of the first buffered signal and the second buffered signal. The comparison signal carries or comprises information based on the calibration signal. Preferably, the comparison unit is arranged for providing a comparison signal that is based on the calibration signal part carried or comprised in first buffered signal and the calibration signal part carried or comprised in the second buffered signal. The carried or comprised information of the comparison signal is typically information or influence of the calibration signal working from the calibration source through the human body, the first respectively second conductive paths and the first respectively second receive buffers. The carried or comprised information of the comparison signal is typically a difference in information or influence of the calibration signal working from the calibration source through the human body, the first respectively second conductive paths and the first respectively second receive buffers. The comparison signal is typically an analogous signal. The comparison signal may be digital. The medical probe buffer comprises a controller. The controller is arranged for controlling the first bandwidth adaptation unit. The first bandwidth adaptation unit is controlled based on the comparison signal. The controlling of the first bandwidth adaptation unit by the controller is performed such that the difference between the first bandwidth and the second bandwidth is reduced. The reduction of this difference may be typed as calibrating the first and second bandwidth.

[0020] The first conductive path has a first bandwidth. The first conductive path has also sloped sections next to the first bandwidth, more specifically adjacent to the first bandwidth. The second conductive path has a second bandwidth. The second conductive path has also sloped sections next to the second bandwidth, more specifically adjacent to the second bandwidth.

[0021] It is an insight of the inventor that although the magnitude is shown as flat or sloped with abrupt changes in a Bode magnitude diagram, the magnitude is a constantly changing value. Furthermore, the gain in the first and second conductive paths depends, next to the amplification or multiplication of the buffer on the impedance of the respective conductive paths, such as the resistance and capacitance in the respective conductive paths. The amplification of the respective receive buffers is typically differing only with a small amplification error from each other. The difference in amplification of the receive buffers may be neglected, as the dominant factor is typically the bandwidth variation due to the variation of the electrode impedance. Therefore, calibrating the descending or sloped part of the first conductive path aligns or calibrates the first bandwidth towards the second bandwidth, preferably aligns or calibrates the boundary of the bandwidth and / or cutoff point or frequency, more preferably aligns or calibrates the upper boundary of the bandwidth and / or upper cutoff point or frequency. And as the magnitude is already changing well within the bandwidth, such as before the upper cutoff point, the calibration signal may use already frequencies within the first and / or second bandwidth. A difference in the first and second bandwidth causes a common mode signal when comparing, such as subtracting, these two physiological signals. Aligning the first and second bandwidth has the technical effect of reducing the common mode signal. Furthermore, aligning the first and second bandwidth has the technical effect that the common mode signal to differential mode signal conversion is minimized.

[0022] According to another aspect, a medical probe comprising: a medical probe buffer according to any of the claims or embodiments; a first receive wire couplable to the first receive buffer; a second receive wire couplable to the second receive buffer; and a transmit wire couplable to the calibration source. The medical probe provides similar or even the same advantages as the medical probe buffer.

[0023] According to another aspect, a medical device for measuring a physiological signal of a human body, comprising: a medical probe arranged for measuring the physiological signals according to any of the claims or embodiments; and a measuring device adapted for measuring buffered signals from the medical probe. The medical device provides similar or even the same advantages as the medical probe buffer and / or the medical probe.

[0024] According to another aspect, a method for a medical probe buffer for buffering measured physiological signals of a human body, comprising: buffering a first measured signal based on a first physiological signal of the human body via a first conductive path having a first bandwidth, for providing a first buffered signal based on buffering the first measured signal; buffering a second measured signal based on a second physiological signal of the human body via a second conductive path having a second bandwidth, for providing a second buffered signal based on buffering the second measured signal; generating a calibration signal provided to the human body for influencing the first measured signal and the second measured signal; providing a comparison signal based on the comparison of the first buffered signal and the second buffered signal, wherein the comparison signal carries information based on the calibration signal; and adapting the first bandwidth based on the comparison signal such that the difference between the first bandwidth and the second bandwidth is reduced. The method provides similar or even the same advantages as the medical probe buffer.

[0025] According to another aspect of the invention, a probe buffer for buffering measured signals of an object generating or conducting these signals, preferably electrical signals, wherein the measured signals may be a physiological signal of a human body, comprising: a first receive buffer comprising a first receive input adapted for receiving a first measured signal based on a first generated or conducted signal via a first conductive path having a first bandwidth, and arranged for providing a first buffered signal based on buffering the first measured signal; a first bandwidth adaptation unit arranged for adapting the first bandwidth; a second receive buffer comprising a second receive input adapted for receiving a second measured signal based on a second generated or conducted signal via a second conductive path having a second bandwidth, and arranged for providing a second buffered signal based on buffering the second measured signal; a calibration source arranged for generating a calibration signal provided to the object for influencing the first measured signal and the second measured signal; a comparison unit arranged for providing a comparison signal based on the comparison of the first buffered signal and the second buffered signal, wherein the comparison signal carries information based on the calibration signal; and a controller arranged for controlling the first bandwidth adaptation unit based on the comparison signal such that a difference between the first bandwidth and the second bandwidth is reduced.

[0026] DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0027] In an embodiment of the medical probe buffer, the medical probe buffer comprises a second bandwidth adaptation unit arranged for adapting the second bandwidth, wherein the controller is arranged for controlling the second bandwidth adaptation unit based on the comparison signal such that the difference between the first bandwidth and the second bandwidth is reduced. The addition of the second bandwidth adaptation unit advantageously allows to adapt the first bandwidth towards the second bandwidth or vice versa or combinations thereof. The addition of the second bandwidth adaptation unit advantageously allows to adapt the bandwidths such that the bandwidths are optimized, preferably maximize the bandwidths. Maximizing the bandwidth is defined as attenuating frequencies as at least as possible, more specifically starting at the lowest frequencies.

[0028] In a further embodiment of the medical probe buffer, controlling the first bandwidth adaptation unit and the second bandwidth adaptation unit further comprises minimizing adapting of the first conductive path and the second conductive path. The bandwidth adaptation unit adapting either or both bandwidths typically is reducing that specific bandwidth. The bandwidth adaptation unit in a condition not adapting the bandwidth of the respective conductive path typically provides the broadest bandwidth for that conductive path. Reducing a bandwidth typically reduces the information comprised in the signal conducted via the conductive path having that bandwidth. Minimizing adapting bandwidths advantageously provides that signals conducted via respective conductive paths comprise more information, preferably attenuates the respective signals over as less as possible frequencies, more preferably the lower frequencies, and / or the frequency range exposed to a first order attenuation in the conductive path with and / or without attenuation applied is minimized.

[0029] In a further embodiment of the medical probe buffer, reducing the difference between the first bandwidth and the second bandwidth has a higher priority compared to minimizing adapting of the first conductive path and the second conductive path. Prioritizing reducing the difference advantageously reduces the signal difference, typically for one or more specific frequency ranges, such as a common mode signal of the measured signals.

[0030] In an embodiment of the medical probe buffer, the comparison unit comprises a bandpass filter having a bandpass bandwidth comprising the calibration signal. Assigning a specific bandpass bandwidth or bandpass frequency range allows to assign another frequency range, preferably non-overlapping or minimally overlapping with the bandpass bandwidth, to the measured physiological signal of the human body for advantageously limiting the influence of the measured physiological signal of the human body on the calibration signal. Also, with the additional feature that the calibration signal is limited to the bandpass bandwidth, the influence on the measurement of the measured physiological signal of the human body by the calibration signal is advantageously minimized or reduced.

[0031] The calibration signal may comprise a frequency or frequency range. The calibration signal may be located outside or adjacent or partly overlapping with the frequency range present in the physiological signal of the human body. This advantageously allows the calibration signal to reduce or minimize the influence on the measurement of the physiological signal.

[0032] Furthermore, the other way around, the measured physiological signal of the human body will have a reduced or minimal influence on the measurement of the calibration signal. This reduced or minimal influence advantageously allows the controller to control the at least one bandwidth adaptation unit quicker and / or more accurate.

[0033] In an embodiment of the medical probe buffer, the calibration signal has one or more calibration frequencies, preferably a single calibration frequency. Limiting the calibration signal to one or more frequencies advantageously limits or reduces the influence of the calibration signal on the measured physiological signal of the human body. The calibration signal may advantageously be filtered out more easily from the measured signal, typically with a sharp and / or narrow bandpass filter. The narrow filter may be for example also be a notch filter or even an QI demodulator.

[0034] In an embodiment of the medical probe buffer, the calibration signal is outside the second bandwidth for advantageously minimizing or reducing the influence of the calibration signal on the first and / or second measured physiological signal of the human body.

[0035] In an embodiment of the medical probe buffer, the calibration signal is outside the first bandwidth for advantageously minimizing or reducing the influence of the calibration signal on the first and / or second measured physiological signal of the human body.

[0036] In a preferred embodiment, the calibration signal is outside the first and the second bandwidth. Preferably, the calibration signal is outside the first and the second bandwidth independent of if or how the first and / or second bandwidth adaptation unit adapts the bandwidth.

[0037] In an embodiment of the medical probe buffer, the first bandwidth is a pass bandwidth, preferably a low pass bandwidth; and / or the second bandwidth is a pass bandwidth, preferably a low pass bandwidth. Typically, the physiological signal of the human body is in the low frequency range. The first and / or the second bandwidth are adapted to this type of physiological signal or signals.

[0038] In an embodiment of the medical probe buffer, an attenuation slope adjacent to the bandwidth is a first or higher order slope, preferably a first, second or third order slope, more preferably a first or second order slope, most preferably a first order slope. Typically, the bandwidth may be modelled as a low frequency pass model of the first order, such as a resistor in series in the conductive path and a capacitance parallel to the conductive path.

[0039] In an embodiment of the medical probe buffer, the first receive buffer and / or the second receive buffer have a bandwidth larger than the first bandwidth and / or the second bandwidth, respectively. The bandwidths of the respective buffers have neglectable influence on the controller controlling the first and / or second bandwidth adaptation units. The controlling is therefore simplified and more stable as the controlling depends only or at least primarily on the respective conductive paths and more particularly in the change of the respective conductive paths. Furthermore, the bandwidth of the respective buffers may be ignored under this condition for improved preservation of the information contained in the measured signals. In an embodiment of the medical probe buffer, the first bandwidth without being adapted by the first bandwidth adaptation unit is larger compared to the second bandwidth. The first bandwidth being larger compared to the second bandwidth advantageously allows the first bandwidth adaptation unit to adapt the first bandwidth towards the second bandwidth.

[0040] In an embodiment of the medical probe buffer, the comparison unit is arranged for basing the comparison signal on subtracting the first buffer signal and the second buffer signal from each other. A difference is advantageously determined by subtracting the first and second buffer signal from each other, more specifically subtracting the first and second buffer signal from each other for a specific frequency or frequency range.

[0041] In an embodiment of the medical probe buffer, the controller is arranged for maintaining the first bandwidth adaptation unit for measuring the physiological signals; and when the second adaptation unit is present, the controller is arranged for maintaining the second adaptation unit for measuring the physiological signals. The controller maintains the respective adaptation unit at a particular setting for advantageously minimizing the influence on the measured first and / or second signals. Maintaining may also be typed as measuring, such as measuring the physiological signals of the human body. In this embodiment, the controller may assign time intervals for measuring the physiological signals of the human body and other time intervals for adapting the first and / or the second bandwidth, effectively time multiplexing the measuring and adaptation.

[0042] In a further embodiment of the medical probe buffer, the controller is arranged for managing the calibration source; and maintaining for measuring of the controller comprises stop generating the calibration signal. During the maintaining feeding of the calibration signal to the human body may be interrupted, disabled, or prevented for minimizing or preventing influence of the calibration signal on the first measured signal and / or the second measured signal during the measuring for advantageously improving the maintaining. The calibration source may be disabled, interrupted or decoupled from the human body during at least part of the maintaining.

[0043] In a further embodiment of the medical probe buffer, the controller alternates between maintaining and controlling. Maintaining and controlling may be alternated at regular intervals. Maintaining and controlling may alternate depending on the amount of adapting during the controlling phase. Alternating between maintaining and controlling may startup with controlling for advantageously correcting the respective bandwidths before maintaining or measuring.

[0044] A bandwidth is a frequency range wherein an attenuation or an amplification of a signal is substantially equal and / or within a predefined range; the frequency range has a high cutoff frequency; and the first bandwidth adaptation unit is arranged for reducing the difference between a high cutoff frequency of the first bandwidth and a high cutoff frequency of the second bandwidth. The amplification is typically well controlled or regulated. Controlling or regulating the cutoff frequency therefore aligns the first and second bandwidths. Although the idealized, or first order approximation, of the amplitude Bode-diagram of a low pass bandwidth comprises a flat section and a first order decline of the amplitude, it is noted that in reality the decrease in amplitude is already set in or starting before the cut-off frequency. The cut-off frequency is typically the -3 dB point, indicating an amplitude decrease of half the amplitude relative to the highest amplitude in the flat section, typically at or close to 0 Hz. This decrease of the amplitude before the cut-off frequency may advantageously already be used by the comparison unit and subsequently by the controller for adapting the first and / or second bandwidth adaptation unit.

[0045] A bandwidth may be defined as the numerical difference between the upper and lower frequencies of a band of electromagnetic radiation, especially an assigned range of radio frequencies. A bandwidth may alternatively be defined as the smallest range of frequencies constituting a band within which a particular signal can be transmitted without distortion. A bandwidth incorporating 0 Hz may be typed as a low pass bandwidth. A bandwidth incorporating infinity Hz may be typed as a high pass bandwidth. A bandwidth incorporating not 0 Hz as well as not infinity Hz may be typed as a bandpass bandwidth.

[0046] A difference in the sloped section of the first and second conductive paths, specifically in the sloped section adjacent to the first and second bandwidth sections, causes a common mode signal when comparing, such as subtracting, these two physiological signals. Aligning the sloped sections has the technical effect of reducing the common mode signal.

[0047] In an embodiment of the medical probe buffer, the first bandwidth adaptation unit comprises a first capacitor arranged for adapting the first bandwidth. Typically, this first capacitor is arranged in parallel over the first conductive path. The first capacitor may comprise several smaller capacitors that may be individually switched capacitors for adapting the capacitance of the first capacitor. The first capacitor may comprise other means for adapting the capacitance of the first capacitor, such as a capacitor having a capacitance based on a bias voltage over the capacitor. The first capacitor may comprise means for stepwise and / or gradually changing the capacitance of the first capacitor.

[0048] In a further embodiment of the medical probe buffer, the controller controls the capacitance of the first capacitor for advantageously adapting the first bandwidth.

[0049] In an embodiment of the medical probe buffer, the first capacitor is advantageously partly, gradually and / or stepwise couplable to the first conductive path for partly, gradually, and / or stepwise adapting the first bandwidth, respectively.

[0050] In a further embodiment of the medical probe buffer, the first capacitor is advantageously couplable as a branch to the first conductive path for adapting the first bandwidth.

[0051] In a further embodiment of the medical probe buffer, the first capacitor is couplable to ground or at least one side is couplable to ground.

[0052] In a further embodiment of the medical probe buffer, the first capacitor comprises a first side and a second side; the first side is coupled to the first conductive path; the first adaptation unit comprises a first feedback buffer having a first amplification; the first feedback buffer is arranged between the first conductive path and the second side of the first capacitor; and the controller controls the first amplification. Controlling the feedback amplification advantageously allows to control the capacitance perceived by the first conductive path due to the first capacitor.

[0053] The feedback amplification can be positive or negative, preferably negative. The feedback buffer with a negative value for the feedback amplification advantageously increases the capacitance of the associated capacitor perceived by the signal conducted along the respective conductive path.

[0054] In an embodiment of the medical probe buffer, the measured physiological signal is a bioelectric signal. A bioelectric signal may be an electrical signal associated with muscle activity, such as the heart, intestines or muscles in the extremities. A bioelectrical signal may be an electrical signal associated with brain activity.

[0055] In an embodiment of the medical probe buffer, the medical probe buffer comprises an IC package, wherein the IC package advantageously comprises one or more of the first receive buffer, a first bandwidth adaptation unit, the second receive buffer, the comparison unit, and the controller. In some embodiments of the invention, the different buffers may be arranged in one IC, whereby the IC replaces the buffers integrated in the IC. In some embodiments, the IC may comprise more parts of the medical probe buffer, preferably all parts of the medical probe buffer.

[0056] BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The invention will be apparent from and elucidated further with reference to the embodiments described by way of example in the following description and with reference to the accompanying drawings, in which:

[0058] Figure 1 schematically shows a medical probe buffer according to the prior art;

[0059] Figure 2 schematically shows a medical probe buffer according to the invention; and

[0060] Figure 3 schematically shows a medical probe buffer according to the invention.

[0061] The figures are purely diagrammatic and not drawn to scale. In the figures, elements which correspond to elements already described may have the same reference numerals.

[0062] LIST OF REFERENCE NUMERALS

[0063] DETAILED DESCRIPTION OF THE FIGURES

[0064] The following figures may detail different embodiments. Embodiments can be combined to reach an enhanced or improved technical effect. These combined embodiments may be mentioned explicitly throughout the text, may be hint upon in the text or may be implicit. Figure 1 schematically shows a medical probe buffer 50 -with a dotted boxaccording to the prior art.

[0065] The medical probe buffer comprises a first receive port 113, a second receive port 133, a first receive buffer 110, a second receive buffer 130, a ground port 152, and a ground G.

[0066] The first receive buffer comprises a first receive input 111 , and a first receive output 112. The first receive input receives a first measured signal 116. The first receive output provides a first buffered signal 117. The first receive buffer typically has a high input impedance, a low output impedance and a first transfer function specifying the output voltage based on amplification of the input voltage. The first transfer function may be modelled as a low pass bandwidth, typically having a cut-off frequency higher compared to the bandwidth of the signal provided to the first receive input.

[0067] The second receive buffer comprises a second receive input 131 , and a second receive output 132. The second receive input receives a first measured signal 136. The second receive output provides a second buffered signal 137. The second receive buffer typically has a high input impedance, a low output impedance and a second transfer function specifying the output voltage based on amplification of the input voltage. The second transfer function may be modelled as a low pass bandwidth, typically having a cut-off frequency higher compared to the bandwidth of the signal provided to the second receive input.

[0068] The first receive port is conductively coupled to the first receive buffer input. The second receive port is conductively coupled to the second receive buffer input. The ground port is conductively coupled to ground G.

[0069] Figure 1 further shows a human 10 having a human body 11 coupled to the medical probe buffer via a ground wire 40, a first sensor wire 33 and a second sensor wire 34. The ground wire and / or ground may be modelled with a ground wire model 41 comprising a ground wire impedance 43 in series and with parallel to the impedance a common mode source 42. The common mode source may have one or more frequencies with a particular amplitude and phase. The one or more frequencies with an amplitude are shown in a frequency plot 61 provided to the human body for illustrative purposes as a single frequency having a particular amplitude.

[0070] Figure 1 further shows the first sensor wire attached to the human body for picking up a first physiological signal 21 , typically an electrical physiological signal, The first sensor wire conducts this physiological signal to a first receive port 113 of the medical probe buffer. The first sensor wire may be modelled 35 with a first sensor wire impedance 37. The first sensor wire impedance typically comprises a series resistance and a capacitance between the wire and ground. The first conductive path comprises the conductive path from ground via the ground wire, the human body, the first sensor wire, the first receive port, the internal conductive coupling to the first receive buffer input, and the first receive buffer input. The input impedance of the first receive buffer and the internal conductive coupling is modelled by a first capacitor 71 .

[0071] Figure 1 further shows the second sensor wire attached to the human body for picking up a second physiological signal 22, typically an electrical physiological signal, The second sensor wire conducts this physiological signal to a second receive port 133 of the medical probe buffer. The second sensor wire may be modelled 36 with a second sensor wire impedance 38. The second sensor wire impedance typically comprises a series resistance and a capacitance between the wire and ground. The second conductive path comprises the conductive path from ground via the ground wire, the human body, the second sensor wire, the second receive port, the internal conductive coupling to the second receive buffer input, and the second receive buffer input. The input impedance of the second receive buffer and the internal conductive coupling is modelled by a second capacitor 72.

[0072] The first conductive path has a first bandwidth 118 shown modelled in a frequency plot in figure 1 . The second conductive path has a second bandwidth 138 shown modelled in a frequency plot in figure 1. Both bandwidths are shown approximated with a low pass bandwidth having different cut-off frequencies. The cutoff frequency in this example of the first bandwidth is higher compared to the second bandwidth. The reason for this difference in this example is the lower resistive impedance of the first conductive wire compared to the second conductive wire. This difference may also occur due to a different impedance, such as a different resistance, between the ground wire attached to the human body and the first sensor wire attached to the human body on the one hand and the ground wire attached to the human body and the second wire attached to the human body. In essence, this difference may be due to different impedances, such as resistances, between wires and / or conductive paths through the human body.

[0073] The common mode voltage of the first buffered signal is shown in a first frequency plot 119. This common mode voltage is due to the first conductive path in combination with the transfer function of the first receive buffer. The common mode voltage of the second buffered signal is shown in a second frequency plot 139. This common mode voltage is due to the second conductive path in combination with the transfer function of the second receive buffer. The common mode voltages in both the measured signals result from the common mode voltage as shown in the plot 61 .

[0074] The difference in conductive paths and / or receive buffers, typically dominated by the difference in conductive paths, may result in different common mode voltages in the buffered signals as shown in the first buffered signal frequency plot 119 compared to the second buffered signal frequency plot 139. For illustrative purposes, only the common mode voltages are shown and not the resulting frequencies with their amplitudes resulting from the respective measured physiological signals.

[0075] Only for explanatory reasons the medical probe buffer comprises a comparison unit 150. The comparison unit subtracts the second buffered signal from the first buffered signal. The resulting comparison signal 151 has a common mode signal as shown in the comparison frequency plot 159. The resulting common mode voltage in the comparison signal typically has negative consequences on the ability of any electronics following the buffers, such as amplifiers, to measure, determine or digitize the buffered signals. An example of these issues may be clipping of the further amplified buffered signals due to the present common mode voltage. Specifically, comparison between buffered signals becomes difficult for any electronics following the buffers due to for example clipping. Identifying the issue and the origin of the common mode voltage is an insight of the inventors.

[0076] Figure 2 schematically shows a medical probe buffer 100 -with a dotted boxaccording to the invention.

[0077] The medical probe buffer is arranged for buffering measured physiological signals of a human body 11 of a human 10. The medical probe buffer comprises a first receive buffer 110, a first bandwidth adaptation unit 120, a second receive buffer 130, a calibration source 140, a comparison unit 150 and a controller 160.

[0078] The first receive buffer 110 comprises a first receive input 111. The first receive input is adapted for receiving a first measured signal 116. The first measured signal is based on a first physiological signal 115 of the human body via a first conductive path 114. The first conductive path has a first bandwidth 118. The first receive buffer is arranged for providing a first buffered signal 117 based on buffering the first measured signal. The first receive buffer may comprise a first receive output 112 adapted to provide the first buffered signal.

[0079] The medical probe buffer may comprise a first receive port 113. The first receive port is conductively coupled to the first receive buffer input for bringing an external signal from the first receive port to the internal first receive input.

[0080] The first receive buffer typically has a high input impedance, a low output impedance and a first transfer function specifying the output voltage based on amplification of the input voltage. The first transfer function may be modelled as a low pass bandwidth, typically having a cut-off frequency higher compared to the bandwidth of the signal provided to the first receive input.

[0081] The second receive buffer 130 comprises a second receive input 131. The second receive input is adapted for receiving a second measured signal 136 based on a second physiological signal 135 of the human body via a second conductive path 134. The second conductive path has a second bandwidth 138. The second receive buffer is arranged for providing a second buffered signal 137 based on buffering the second measured signal. The second receive buffer may comprise a second receive output 132 adapted to provide the second buffered signal.

[0082] The medical probe buffer may comprise a second receive port 133. The second receive port is conductively coupled to the second receive buffer input for bringing an external signal from the second receive port to the internal second receive input.

[0083] The second receive buffer typically has a high input impedance, a low output impedance and a second transfer function specifying the output voltage based on amplification of the input voltage. The second transfer function may be modelled as a low pass bandwidth, typically having a cut-off frequency higher compared to the bandwidth of the signal provided to the second receive input.

[0084] The calibration source 140 is arranged for generating a calibration signal 141 . The calibration signal is provided to the human body for influencing the first measured signal 116 and the second measured signal 136. Influencing the first and second measured signals is typically via respectively the first and second conductive paths.

[0085] The comparison unit 150 is arranged for providing a comparison signal 151. The comparison signal is based on the comparison of the first buffered signal and the second buffered signal. Further, the comparison signal carries information based on the calibration signal. This information is typically based on via the influences of the calibration signal on the first and second measured signals.

[0086] The controller 160 is arranged for controlling the first bandwidth adaptation unit. The controlling is based on the comparison signal. The controlling is aimed at reducing a difference between the first bandwidth and the second bandwidth.

[0087] The medical probe buffer may comprise a ground port 152, and a ground G. The ground port is conductively coupled to ground G. Ground provides a voltage reference. Unless otherwise specified, voltages are relative to this ground.

[0088] Figure 2 further shows a human 10 having a human body 11 coupled to the medical probe buffer via a ground wire 40, a first sensor wire 33 and a second sensor wire 34. The ground wire and / or ground may be modelled with a ground wire model 41 comprising a ground wire impedance 43 in series and with parallel to the impedance a common mode source 42. The common mode source may have one or more frequencies with a particular amplitude and phase. Further, the calibration signal may have one or more frequencies with a particular amplitude and phase.

[0089] The one or more frequencies with an amplitude of the calibration signal are shown in a frequency plot 60 for illustrative purposes as a single frequency having a particular amplitude. The one or more frequencies with an amplitude of the common mode source are added to the calibration signal. The resulting signal is provided to the human body as shown in a frequency plot 61 . For illustrative purposes, a single frequency having a particular amplitude for the common mode voltage and the calibration signal are shown.

[0090] Figure 2 further shows the first sensor wire attached to the human body for picking up a first physiological signal 21 , typically an electrical physiological signal. The first sensor wire conducts this physiological signal to the medical probe buffer, typically to a first receive port 113 of the medical probe buffer. The first sensor wire may be modelled 35 with a first sensor wire impedance 37. The first sensor wire impedance typically comprises a series resistance and a capacitance between the wire and ground. The first conductive path typically comprises the conductive path from ground via the calibration source, the ground wire, the human body, the first sensor wire, the first receive port, the internal conductive coupling to the first receive buffer input, and the first receive buffer input.

[0091] Figure 2 further shows the second sensor wire attached to the human body for picking up a second physiological signal 22, typically an electrical physiological signal. The second sensor wire conducts this physiological signal to the medical probe buffer, typically to a second receive port 133 of the medical probe buffer. The second sensor wire may be modelled 36 with a second sensor wire impedance 38. The second sensor wire impedance typically comprises a series resistance and a capacitance between the wire and ground. The second conductive path typically comprises the conductive path from ground via the ground wire, the human body, the second sensor wire, the second receive port, the internal conductive coupling to the second receive buffer input, and the second receive buffer input.

[0092] The first bandwidth adaptation unit 120 is arranged for adapting the first bandwidth. The first bandwidth adaptation unit may comprise a first capacitor 121 . The input impedance of the first receive buffer and the internal conductive coupling may be comprised in the first capacitor as a base or offset capacitance value. The first capacitor is adaptable, typically within a range, more typically a predefined range. The adaptation of the first capacitor may be performed based on a first adaptation signal 161 from the controller.

[0093] The medical probe buffer may comprise a second bandwidth adaptation unit

[0094] 170. The second bandwidth adaptation unit 120 is arranged for adapting the second bandwidth. The second bandwidth adaptation unit may comprise a second capacitor

[0095] 171. The input impedance of the second receive buffer and the internal conductive coupling may be comprised in the second capacitor as a base or offset capacitance value. The second capacitor is adaptable, typically within a range, more typically a predefined range. The adaptation of the second capacitor may be performed based on a second adaptation signal 162 from the controller.

[0096] The first conductive path has a first bandwidth 118 shown modelled in a frequency plot in figure 2. The second conductive path has a second bandwidth 138 shown modelled in a frequency plot in figure 2. Both bandwidths are shown approximated with a low pass bandwidth having cut-off frequencies.

[0097] In this example, the first conductive wire has a lower resistive impedance compared to the second conductive wire. This difference may occur due to a different impedance, such as a different resistance, between the ground wire attached to the human body and the first sensor wire attached to the human body on the one hand and the ground wire attached to the human body and the second wire attached to the human body. In essence, this difference may be due to different impedances, such as resistances, between wires and / or conductive paths through the human body. These differences may influence the first and the second bandwidths. These differences, as a first order approximation, may influence the cut-off frequencies of the first and the second bandwidths. The cut-off frequency in this example of the first bandwidth is higher compared to the second bandwidth without adaptation.

[0098] It is noted that based on more accurate models, more accurate compared to the first order approximation, the calibration signal, more specifically the frequency of the calibration signal, does not have to be restricted and / or limited to the sloped sections of the first and / or second bandwidth but may also be arranged to the flat sections, preferably the flat sections close to the cut-off frequencies, of the first and / or second bandwidths.

[0099] The common mode voltage of the first buffered signal is shown in a first frequency plot 119. This common mode voltage is due to the first conductive path in combination with the transfer function of the first receive buffer. The common mode voltage of the second buffered signal is shown in a second frequency plot 139. This common mode voltage is due to the second conductive path in combination with the transfer function of the second receive buffer. The common mode voltages in both the measured signals result from the common mode voltage as shown in the plot 61 .

[0100] A difference in conductive paths and / or receive buffers, typically dominated by the difference in conductive paths, may result in different common mode voltages in the buffered signals. The comparison unit compares, preferably subtracts, the second buffered signal from the first buffered signal. The difference in conductive paths and / or receive buffers results in a comparison signal 151 having a common mode signal as well as a signal component resulting from the calibration signal. Typically, the amplitude of the signal component resulting from the calibration signal typically relates to the amplitude of the common mode signal. Further typically, the difference between the first and second bandwidths relate to the amplitude of the signal component resulting from the calibration signal and / or the common mode signal.

[0101] The controller is arranged for receiving the comparison signal. The comparison signal may be filtered or preprocessed before provided to the controller. The comparison signal may be digitized before provided to the controller. The controller may be a microprocessor, or digital electronics.

[0102] The controller is arranged for reducing, minimizing and / or limiting the difference between the first bandwidth and the second bandwidth based on the comparison signal, typically the difference in the influence of the calibration signal on the first and second measured signals, more typically the difference in the influence of the calibration signal on the first and second buffered signals. Reducing, minimizing and / or limiting the difference in this embodiment results in adapting the capacitance of the first capacitor and / or the second capacitor, if present. Reducing, minimizing and / or limiting the difference results in a shown first buffered signal frequency plot 119 and a shown second buffered frequency plot 139. The influence of the modelled common mode source 42 and the calibration source 140 are modelled in the frequency plots of the first and second buffered signals as respective single frequencies. It is further noted that due to the adaptation of the first bandwidth adaptation unit and / or the second bandwidth adaptation unit, if present, the differences in the amplitudes of the modelled frequencies are reduced, minimized and / or limited as shown in the frequency plot 159 of the comparison signal. Reducing, minimizing and / or limiting the difference in the amplitudes of the modelled frequencies has the technical effect that the influences of the calibration source as well as the common mode source on the comparison signal are reduced, minimized and / or limited. This simplifies the requirements for any electronics, such as amplifiers, buffers and / or digitizers, following or coupled to the medical probe buffer for further processing or measuring the physiological signals of the human body.

[0103] Figure 3 schematically shows a medical probe buffer 100 -with a dotted boxaccording to the invention. Equal numbers and labels mentioned in figure 2 and figure 3 may have the same name and / or function.

[0104] The first bandwidth adaptation unit may comprise a first feedback buffer 122. The first feedback buffer and the first capacitor are coupled in series. The input of the first feedback buffer and the other side of the first capacitor are coupled to the conductive path between the first receive port and the first receive input, as shown in figure 3. The feedback buffer has a multiplication factor multiplying the input voltage for providing an output voltage. The first adaptation signal may adapt the multiplication factor of the first feedback buffer. The multiplication factor of the feedback buffer is typically negative. The first feedback buffer influences the capacitance of the first capacitor perceived by the first conductive path. This perceived capacitance is adapted by adapting the multiplication factor.

[0105] The second bandwidth adaptation unit, if present, may comprise a second feedback buffer 172. The second feedback buffer and the second capacitor are coupled in series. The input of the second feedback buffer and the other side of the second capacitor are coupled to the conductive path between the second receive port and the second receive input, as shown in figure 3. The feedback buffer has a multiplication factor multiplying the input voltage for providing an output voltage. The second adaptation signal may adapt the multiplication factor of the second feedback buffer. The multiplication factor of the feedback buffer is typically negative. The second feedback buffer influences the capacitance of the second capacitor perceived by the second conductive path. This perceived capacitance is adapted by adapting the multiplication factor.

[0106] The addition of feedback buffers to the respective bandwidth adaption units provides another embodiment of obtaining the technical effect described for figure 2 as well as mentioned in other parts of the description as technical effect and / or advantage.

[0107] Examples, embodiments or optional features, whether indicated as nonlimiting or not, are not to be understood as limiting the invention as claimed. It should be noted that the figures are purely diagrammatic and not drawn to scale. In the figures, elements which correspond to elements already described may have the same reference numerals.

[0108] The term “substantially” herein, such as in “substantially all emission” or in “substantially consists”, will be understood by the person skilled in the art. The term “substantially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially may also be removed. Where applicable, the term “substantially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. The term “comprise” includes also embodiments wherein the term “comprises” means “consists of’.

[0109] The term "functionally" will be understood by, and be clear to, a person skilled in the art. The term “substantially” as well as “functionally” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective functionally may also be removed. When used, for instance in “functionally parallel”, a skilled person will understand that the adjective “functionally” includes the term substantially as explained above. Functionally in particular is to be understood to include a configuration of features that allows these features to function as if the adjective “functionally” was not present. The term “functionally” is intended to cover variations in the feature to which it refers, and which variations are such that in the functional use of the feature, possibly in combination with other features it relates to in the invention, that combination of features is able to operate or function. For instance, if an antenna is functionally coupled or functionally connected to a communication device, received electromagnetic signals that are receives by the antenna can be used by the communication device. The word “functionally” as for instance used in “functionally parallel” is used to cover exactly parallel, but also the embodiments that are covered by the word “substantially” explained above. For instance, “functionally parallel” relates to embodiments that in operation function as if the parts are for instance parallel. This covers embodiments for which it is clear to a skilled person that it operates within its intended field of use as if it were parallel.

[0110] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0111] The devices or apparatus herein are amongst others described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation or devices in operation.

[0112] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device or apparatus claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0113] The invention further applies to an apparatus or device comprising one or more of the characterising features described in the description and / or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterising features described in the description and / or shown in the attached drawings.

[0114] The various aspects discussed in this patent can be combined in order to provide additional advantages. Furthermore, some of the features can form the basis for one or more divisional applications.

Claims

AMENDED CLAIMS received by the International Bureau on 27 June 2025 (27.06.2025)1 . Medical probe buffer (100) for buffering measured physiological signals of a human body (11 ), comprising:- a first receive buffer (110) comprising a first receive input (111 ) adapted for receiving a first measured signal (116) based on a first physiological signal (115) of the human body via a first conductive path (31 ) having a first bandwidth (118), and arranged for providing a first buffered signal (117) based on buffering the first measured signal;- a first bandwidth adaptation unit (120) arranged for adapting the first bandwidth;- a second receive buffer (130) comprising a second receive input (131 ) adapted for receiving a second measured signal (136) based on a second physiological signal (135) of the human body via a second conductive path (32) having a second bandwidth (138), and arranged for providing a second buffered signal (137) based on buffering the second measured signal;- a calibration source (140) arranged for generating a calibration signal (141 ) provided to the human body for influencing the first measured signal and the second measured signal;- a comparison unit (150) arranged for providing a comparison signal (151 ) based on the comparison of the first buffered signal and the second buffered signal, wherein the comparison signal carries information based on the calibration signal; and- a controller (160) arranged for controlling the first bandwidth adaptation unit based on the comparison signal such that a difference between the first bandwidth and the second bandwidth is reduced.

2. Medical probe buffer according to the preceding claim, comprising a second bandwidth adaptation unit (170) arranged for adapting the second bandwidth, wherein the controller is arranged for controlling the second bandwidth adaptation unit based on the comparison signal such that the difference between the first bandwidth and the second bandwidth is reduced.

3. Medical probe buffer according to the preceding claim, wherein controlling the first bandwidth adaptation unit and the second bandwidth adaptation unit further comprises minimizing adapting of the first bandwidth and the second bandwidth.

4. Medical probe buffer according to the preceding claim, wherein reducing the difference between the first bandwidth and the second bandwidth has a higher priority compared to minimizing adapting of the first bandwidth and the second bandwidth.

5. Medical probe buffer according to any of the preceding claims, wherein the calibration signal comprises at least one calibration frequency; wherein the comparison unit comprises a bandpass filter having a bandpass bandwidth comprising the at least one calibration frequency.

6. Medical probe buffer according to any of the preceding claims, wherein the calibration signal has one or more calibration frequencies, preferably a single calibration frequency.

7. Medical probe buffer according to any of the preceding claims, wherein the calibration signal is outside the second bandwidth.

8. Medical probe buffer according to any of the preceding claims, wherein the calibration signal is outside the first bandwidth.

9. Medical probe buffer according to any of the preceding claims, wherein the first bandwidth is a pass bandwidth, preferably a low pass bandwidth; and / or wherein the second bandwidth is a pass bandwidth, preferably a low pass bandwidth.

10. Medical probe buffer according to any of the preceding claims, wherein an attenuation slope adjacent to the bandwidth is a first or higher order slope, preferably a first, second or third order slope, more preferably a first or second order slope, most preferably a first order slope.11 . Medical probe buffer according to any of the preceding claims, wherein the first receive buffer and / or the second receive buffer have a bandwidth larger than the first bandwidth and / or the second bandwidth, respectively.

12. Medical probe buffer according to any of the preceding claims, wherein the first bandwidth without being adapted by the first bandwidth adaptation unit is larger compared to the second bandwidth.

13. Medical probe buffer according to any of the preceding claims, wherein the comparison unit is arranged for basing the comparison signal on subtracting the first buffer signal and the second buffer signal from each other.

14. Medical probe buffer according to any of the preceding claims, wherein the controller is arranged for maintaining a first setting of the first bandwidth adaptation unit for measuring the physiological signals; and wherein, when depending on claim 2, the controller is arranged for maintaining a second setting of the second adaptation unit for measuring the physiological signals.

15. Medical probe buffer according to the preceding claim, wherein the controller is arranged for managing the calibration source; and wherein maintaining the first setting and the second setting for measuring of the controller comprises stop generating the calibration signal.

16. Medical probe buffer according to any of the preceding claims 14-15, wherein the controller alternates between maintaining and controlling.

17. Medical probe buffer according to any of the preceding claims, wherein a bandwidth is a frequency range wherein an attenuation or an amplification of a signal is substantially equal and / or within a predefined range; wherein the frequency range has a high cutoff frequency; and wherein the first bandwidth adaptation unit is arranged for reducing the difference between a high cutoff frequency of the first bandwidth and a high cutoff frequency of the second bandwidth.

18. Medical probe buffer according to any of the preceding claims, wherein the first bandwidth adaptation unit comprises a first capacitor (121 ) arranged for adapting the first bandwidth.

19. Medical probe buffer according to the preceding claim, wherein the controller controls the capacitance of the first capacitor for adapting the first bandwidth.

20. Medical probe buffer according to any of the preceding claims, wherein the first capacitor is partly, gradually and / or stepwise couplable to the first conductive path for partly, gradually, and / or stepwise adapting the first bandwidth, respectively.21 . Medical probe buffer according to any of the preceding claims 18-20, wherein the first capacitor is couplable as a branch to the first conductive path for adapting the first bandwidth.

22. Medical probe buffer according to any of the preceding claims 18-21 , wherein the first capacitor is couplable to ground.

23. Medical probe buffer according to any of the preceding claims 18-21 , wherein the first capacitor comprises a first side and a second side; wherein the first side is coupled to the first conductive path; wherein the first adaptation unit (120) comprises a first feedback buffer (122) having a first amplification; wherein the first feedback buffer is arranged between the first conductive path and the second side of the first capacitor; and wherein the controller controls the first amplification.

24. Medical probe buffer according to any of the preceding claims, wherein the measured first physiological signal is a bioelectric signal.

25. Medical probe buffer according to any of the preceding claims, comprising an IC package, wherein the IC package comprises one or more of the first receive buffer, a first bandwidth adaptation unit, the second receive buffer, the comparison unit, and the controller.

26. Medical probe (200) comprising:- a medical probe buffer (100) according to any of the preceding claims 1-25;- a first receive wire couplable to the first receive buffer;- a second receive wire couplable to the second receive buffer; and- a transmit wire couplable to the calibration source.

27. Medical device (300) for measuring physiological signals of a human body, comprising:- a medical probe arranged for measuring the physiological signals according to claim 26; and- a measuring device adapted for measuring buffered signals from the medical probe.

28. Method for a medical probe buffer (100) for buffering measured physiological signals of a human body (11 ), comprising:- buffering a first measured signal based on a first physiological signal of the human body via a first conductive path having a first bandwidth, for providing a first buffered signal based on buffering the first measured signal;- buffering a second measured signal based on a second physiological signal of the human body via a second conductive path having a second bandwidth, for providing a second buffered signal based on buffering the second measured signal;- generating a calibration signal provided to the human body for influencing the first measured signal and the second measured signal;- providing a comparison signal based on the comparison of the first buffered signal and the second buffered signal, wherein the comparison signal carries information based on the calibration signal; and- adapting the first bandwidth based on the comparison signal such that the difference between the first bandwidth and the second bandwidth is reduced.

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