Simulation platform for intravascular image acquisition

Abstract

A circuit and design for an analog front end (AFE) are provided herein. The AFE includes a plurality of sub-stages, each having a plurality of optional or alternative paths to complete the circuit. These pathways may be dynamically set during operation based on the type of imaging catheter used with the AFE, or may be set at the time of manufacture.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 436,241, filed on December 30, 2022, the disclosure of which is incorporated herein by reference. Technical Field

[0003] The present invention relates to medical devices and / or medical device systems. More particularly, the present invention relates to conditioning ultrasound signals for digital processing. Background Art

[0004] A wide variety of in-vivo medical devices have been developed for medical applications, such as intravascular use. Some of these devices include guidewires, catheters, and the like. A subset of these devices includes ultrasound transducers configured to generate ultrasound signals that can be used to recreate images of blood vessels. Preprocessing these signals prior to digitization continues to be necessary. However, due to the wide variety of devices configured for intravascular ultrasound and the varying signal qualities supported by these devices, there is a need for an analog topology to preprocess intravascular ultrasound signals that supports both conventional and improved devices. Summary of the Invention

[0005] The present invention provides an analog platform that can be implemented as an analog front end (AFE) in an ultrasound image acquisition system, such as to acquire intravascular ultrasound signals and generate images based on the signals. It should be noted that the present invention provides an AFE that, in addition to allowing ultrasound signals to be acquired at higher resolution and / or quality than conventional systems, can also be used to acquire ultrasound signals from conventional ultrasound catheter devices. In other words, the provided AFE includes multiple substages, each substage having multiple paths through the substage. These paths can be dynamically set during operation based on the type of imaging catheter used with the AFE, or can be set at manufacturing time. However, it should be noted that setting the paths at manufacturing time does not require modification of the circuit or circuit board itself. Therefore, the analog platform implemented according to the present invention provides both backward compatibility and future applicability.

[0006] In some examples, the present invention may be implemented as an analog front end (AFE) for an in-vivo image acquisition device. The AFE may include a high-pass filter stage, a gain stage, and a low-pass filter stage. The high-pass filter stage may include a plurality of high-pass filters and at least one switch, the at least one switch being selectable to electrically couple one of the plurality of high-pass filters to an input. The gain stage may include: a plurality of voltage attenuators, a plurality of amplifier circuits, and a plurality of jumper positions, wherein one or more jumpers are installed in at least one, but not all, of the plurality of jumper positions to electrically couple one of the plurality of voltage attenuators to an output from the high-pass filter stage, and to electrically couple an output from one of the plurality of voltage attenuators to one of the plurality of amplifier circuits. The low-pass filter stage may include a plurality of low-pass filters and at least one switch, the at least one switch being selectable to electrically couple one of the plurality of low-pass filters to an output from the gain stage.

[0007] In another example of the AFE, the plurality of high pass filters may include a first high pass filter and a second high pass filter, wherein the first high pass filter is a 0 to 12 MHz high pass filter, and wherein the second high pass filter is a 15 to 30 MHz high pass filter.

[0008] In another example of the AFE, at least one switch of the high-pass filter stage may include a first switch and a second switch, and wherein the first switch and the second switch are configured to be dynamically controlled by the controller circuit and are arranged to electrically couple an input to the analog front end to a selected one of the first high-pass filter or the second high-pass filter, and to electrically couple an output from the selected one of the first high-pass filter or the second high-pass filter to an output of the high-pass filter stage.

[0009] In another example of the AFE, the first high pass filter and the second high pass filter are T-type high pass filters including a pair of capacitors arranged in series and an inductor electrically coupled between ground and centers of the pair of capacitors.

[0010] In another example of the AFE, the plurality of voltage attenuators of the gain stage may include a first voltage attenuator and a second voltage attenuator, wherein the first voltage attenuator is a 12 decibel voltage attenuator, and wherein the second voltage attenuator is a 28 decibel voltage attenuator.

[0011] In another example of the AFE, the gain stage further includes a digital-to-analog converter and at least one transimpedance amplifier, wherein the transimpedance amplifier is electrically coupled to a control input of the first voltage attenuator or the second voltage attenuator based on one or more jumpers.

[0012] In another example of an AFE, the plurality of amplifier circuits include a first amplifier circuit and a second amplifier circuit, wherein the first amplifier circuit includes an inductor, an operational amplifier (op amp), and a plurality of resistors arranged to form an amplifier circuit, and wherein the second amplifier circuit includes an op amp and a plurality of resistors arranged to form an amplifier circuit.

[0013] In another example of the AFE, the plurality of voltage attenuators may include a first pair of voltage attenuators and a second pair of voltage attenuators, and wherein one of the amplifier circuits is electrically coupled between a first one of the first pair of voltage attenuators and a first one of the second pair of voltage attenuators based on one or more jumpers.

[0014] In another example of an AFE, the gain stage may include a first gain stage and a second gain stage, wherein the second gain stage includes a limiting operational amplifier (op amp).

[0015] In another example of the AFE, the second gain stage further includes a first amplifier circuit, a second amplifier circuit, and multiple pairs of jumper positions, wherein a pair of jumpers is installed in one of the multiple pairs of jumper positions to electrically couple an input to the second gain stage to a selected one of the first amplifier or the second amplifier, and to electrically couple an output of the selected one of the first amplifier or the second amplifier to a limiting op amp.

[0016] In another example of the AFE, the plurality of low pass filters may include a first low pass filter and a second low pass filter, wherein the first low pass filter is a low pass filter less than or equal to 60 MHz, and wherein the second low pass filter is a low pass filter greater than 60 MHz.

[0017] In another example of an AFE, the AFE includes at least one analog-to-digital converter (ADC) driver.

[0018] In some examples, the present invention can be implemented as an in-vivo image acquisition device, which includes an image acquisition circuit and a digital processing circuit, the image acquisition circuit including an AFE according to any of the aforementioned examples, and the digital processing circuit is arranged to receive a digitized signal from the AFE and generate an image.

[0019] In another example, the in-vivo image capture device may include a motor drive unit (MDU) coupled to the image capture circuitry.

[0020] In another example, the in-vivo image acquisition device may include an intravascular ultrasound catheter coupled to the MDU.

[0021] In some examples, the present invention may be implemented as an in-vivo image acquisition device comprising an image acquisition circuit including an analog front end (AFE); and a digital processing circuit coupled to the AFE. The digital processing circuit is configured to receive a digitized signal from the AFE. The AFE may include a high-pass filter stage, a gain stage, and a low-pass filter stage. The high-pass filter stage may include a plurality of high-pass filters and at least one switch, the at least one switch selectable to electrically couple one of the plurality of high-pass filters to an input. The gain stage may include a plurality of voltage attenuators, a plurality of amplifier circuits, and a plurality of jumper positions, wherein one or more jumpers are installed in at least one, but not all, of the plurality of jumper positions to electrically couple one of the plurality of voltage attenuators to an output from the high-pass filter stage and to electrically couple an output from one of the plurality of voltage attenuators to one of the plurality of amplifier circuits. The low-pass filter stage may include a plurality of low-pass filters and at least one switch, the at least one switch selectable to electrically couple one of the plurality of low-pass filters to an output from the gain stage.

[0022] In another example of the in-vivo image acquisition device, the plurality of high pass filters may include a first high pass filter and a second high pass filter, wherein the first high pass filter is a 0 to 12 MHz high pass filter, and wherein the second high pass filter is a 15 to 30 MHz high pass filter.

[0023] In another example of the in-vivo image acquisition device, at least one switch of the high-pass filter stage includes a first switch and a second switch, and wherein the first switch and the second switch are configured to be dynamically controlled by the controller circuit and are arranged to electrically connect the input to the analog front end to a selected one of the first high-pass filter or the second high-pass filter, and to electrically connect the output from the selected one of the first high-pass filter or the second high-pass filter to the output of the high-pass filter stage.

[0024] In another example of the in-vivo image acquisition device, the first high pass filter and the second high pass filter are T-type high pass filters, which may include a pair of capacitors arranged in series and an inductor electrically coupled between ground and the center of the pair of capacitors.

[0025] In another example of the in-vivo image acquisition device, the plurality of voltage attenuators of the gain stage may include a first voltage attenuator and a second voltage attenuator, wherein the first voltage attenuator is a 12 decibel voltage attenuator, and wherein the second voltage attenuator is a 28 decibel voltage attenuator.

[0026] In some examples, the present invention may be implemented as a system for in vivo image acquisition. The system may include an intravascular ultrasound (IVUS) catheter, a motor drive unit (MDU) coupled to the IVUS catheter, the MDU arranged to rotate the IVUS catheter during operation, and image acquisition circuitry coupled to the MDU. The image acquisition circuitry is arranged to receive a signal comprising an ultrasound indication from the IVUS catheter via the MDU during operation. The image acquisition circuitry may include an analog front end (AFE) arranged to receive a signal comprising an ultrasound indication from the IVUS catheter; and a digital processing circuit coupled to the AFE, the digital processing circuitry being arranged to receive a digitized signal from the AFE, the digitized signal being based in part on the signal comprising the ultrasound indication from the IVUS catheter. The AFE may include a high-pass filter stage, a gain stage, and a low-pass filter stage. The high-pass filter stage may include a plurality of high-pass filters and at least one switch, the at least one switch being selectable to electrically couple one of the plurality of high-pass filters to an input. The gain stage may include a plurality of voltage attenuators, a plurality of amplifier circuits, and a plurality of jumper positions, wherein one or more jumpers are installed in at least one, but not all, of the plurality of jumper positions to electrically couple one of the plurality of voltage attenuators to an output from the high-pass filter stage, and to electrically couple an output from one of the plurality of voltage attenuators to one of the plurality of amplifier circuits. The low-pass filter stage may include a plurality of low-pass filters and at least one switch, the at least one switch being selectable to electrically couple one of the plurality of low-pass filters to an output from the gain stage.

[0027] In another example of the system, the plurality of low pass filters may include a first low pass filter and a second low pass filter, wherein the first low pass filter is a low pass filter less than or equal to 60 megahertz, and wherein the second low pass filter is a low pass filter greater than 60 megahertz.

[0028] In another example of the system, the plurality of voltage attenuators may include a first pair of voltage attenuators and a second pair of voltage attenuators, and wherein one of the amplifier circuits is electrically coupled between a first one of the first pair of voltage attenuators and a first one of the second pair of voltage attenuators based on one or more jumpers. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] To easily identify the discussion of any particular component or act, the highest digit(s) in a reference number refers to the figure number in which the component is first introduced.

[0030] Figure 1 One embodiment of an intravascular imaging system is shown.

[0031] Figure 2A Shown in more detail Figure 1 An embodiment of some portions of an intravascular imaging system.

[0032] Figure 2B Shown in more detail Figure 1 An embodiment of another portion of an intravascular imaging system.

[0033] Figure 3 Shown in more detail Figure 1 An embodiment of yet another portion of an intravascular imaging system.

[0034] Figure 4 One embodiment of an analog front end (AFE) is shown.

[0035] Figure 5 One embodiment of the input stage of an AFE is shown.

[0036] Figure 6 One embodiment of a high-pass filter stage of an AFE is shown.

[0037] Figure 7A One embodiment of a portion of a gain stage of an AFE is shown.

[0038] Figure 7B One embodiment of another portion of the gain stage of the AFE is shown.

[0039] Figure 7C One embodiment of yet another portion of a gain stage of an AFE is shown.

[0040] Figure 7D One embodiment of another portion of the gain stage of the AFE is shown.

[0041] Figure 8A One embodiment of a portion of another gain stage of an AFE is shown.

[0042] Figure 8B One embodiment of another portion of another gain stage of an AFE is shown.

[0043] Figure 9 One embodiment of the low-pass filter and analog-to-digital converter stages of an AFE is shown.

[0044] Figure 10 One embodiment of an AFE is shown. DETAILED DESCRIPTION

[0045] There are a variety of imaging modalities used to assess vascular lesions, such as magnetic resonance imaging (MRI), computed tomography (CT), intravascular ultrasound (IVUS), optical coherence tomography (OCT), optical coherence elastography (OCE), and spectroscopy, which can provide insight into the degree to which vascular lesions deviate from healthy tissue. The present invention relates to IVUS signal acquisition and image generation, and in particular to analog processing of the acquired signals prior to digitization.

[0046] Figure 1 An example IVUS imaging system 100 is shown. The IVUS imaging system 100 includes an image acquisition device 102, an IVUS catheter 104, a motor drive unit (MDU) 106, and an imaging subsystem 108. The image acquisition device 102 is coupled to the IVUS catheter 104 via the MDU 106 and is also coupled to the imaging subsystem 108. In particular, the image acquisition device 102 is coupled to the MDU 106 via an MDU bus 110, and the MDU 106 is coupled to the IVUS catheter 104 via a catheter bus 112. In some embodiments, the MDU bus 110 and the catheter bus 112 can be transmission lines (or other conductors) arranged to transmit signals between various components. For example, the MDU bus 110 and the catheter bus 112 can be arranged to transmit radio frequency signals (e.g., control signals, ultrasound pulse generation signals, ultrasound signals, etc.) between designated components of the IVUS imaging system 100.

[0047] Typically, the image acquisition device 102 is configured to control the MDU 106 and receive signals originating from the IVUS catheter 104 via the MDU 106. Furthermore, the image acquisition device 102 is configured to process the received signals to generate images and transmit the images to the imaging subsystem 108. To this end, the image acquisition device 102 is coupled to the imaging subsystem 108 via an imaging subsystem bus 114, which may be a wired or wireless connection. As a specific example, the imaging subsystem bus 114 may be an Ethernet connection. In some examples, the imaging subsystem 108 may be a display, a tablet computer, or other device configured to display images rendered by the image acquisition device 102. It should be noted that while the imaging subsystem 108 is depicted as being external to the image acquisition device 102, in some embodiments, the imaging subsystem 108 may be incorporated into the same housing as the image acquisition device 102.

[0048] The image acquisition device 102 includes imaging processing circuitry 116, a computer subsystem 118, and other subsystems 120. As described above, the present invention provides an improved simulation platform that can be implemented as part of the image acquisition device 102, and in particular, as part of the imaging processing circuitry 116. However, before describing the AFE to which the present invention relates in detail, a general description of the components of the IVUS imaging system 100 and the image acquisition device 102 is provided. Furthermore, it should be noted that the image acquisition device 102 can be provided to capture in vivo images. Although reference is often made herein to IVUS images, the circuitry of the present invention can be provided as part of the image acquisition device 102 that is coupled to other modalities of in vivo image capture.

[0049] Figure 2A and Figure 2B Show Figure 1 1 and 2. The other subsystems 120 are configured to power the MDU 106 and send signals to the IVUS catheter 104, particularly one or more transducers 202 disposed therein, to cause the IVUS catheter 104 to emit ultrasound signals.

[0050] In addition, the mechanical energy from the MDU 106 can be used to drive the imaging core 204 disposed in the IVUS catheter 104. The one or more transducers 202 are also configured to receive reflected signals (e.g., echo signals, etc.) in response to the transmitted ultrasound signals. These reflected signals are transmitted to the image acquisition device 102 via the catheter bus 112, the MDU 106, and the MDU bus 110 for processing by the imaging processing circuit 116 and the computer subsystem 118.

[0051] In some embodiments, the other subsystems 120 may be configured to control at least one of the frequency or duration of electrical pulses transmitted from the image acquisition device 102 to the MDU 106 to control, for example, the rotation rate of the imaging core 204 by the MDU 106 or the pullback speed or length of the imaging core 204 by the MDU 106 .

[0052] The IVUS catheter 104 includes an elongated member 206 and a hub 208. The elongated member 206 includes a proximal end 210 and a distal end 212. The proximal end 210 of the elongated member 206 can be coupled to the hub 208, and the distal end 212 of the elongated member 206 can be configured and arranged for percutaneous insertion into a patient. Optionally, the IVUS catheter 104 can define at least one flush port, such as flush port 214. The flush port 214 can be defined in the hub 208. The hub 208 can be configured and arranged to be coupled to the MDU 106 of the IVUS imaging system 100.

[0053] In some cases, the elongated member 206 and the hub 208 are formed integrally. In other cases, the elongated member 206 and the catheter hub 208 are formed separately and subsequently assembled.

[0054] Figure 2B1 is a perspective view of one embodiment of the distal end 212 of the elongated member 206 of the IVUS catheter 104. The elongated member 206 includes a sheath 216 having a longitudinal axis (e.g., a central longitudinal axis extending axially through the center of the sheath 216 and / or the IVUS catheter 104) and a cavity 222. An imaging core 224 is disposed in the cavity 218. The imaging core 204 includes an imaging device 220 coupled to the distal end of a drive shaft 222 that can be rotated manually or using a computer-controlled drive mechanism (e.g., the MDU 106). One or more transducers 202 can be mounted to the imaging device 220 and used to send and receive acoustic signals. The sheath 216 can be formed of any flexible, biocompatible material suitable for insertion into a patient. Examples of suitable materials include, for example, polyethylene, polyurethane, plastic, spiral-cut stainless steel, nitinol hypotube, the like, or combinations thereof.

[0055] In some embodiments, for example, as shown in these figures, an array of transducers 202 is mounted to the imaging device 220. Alternatively, a single transducer may be employed. Any suitable number of transducers 202 may be used. For example, there may be 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 16, 20, 25, 50, 100, 500, 1000, or more transducers. As will be appreciated, other numbers of transducers may also be used. When multiple transducers 202 are employed, the transducers 202 may be configured in any suitable arrangement, including, for example, an annular arrangement, a rectangular arrangement, etc.

[0056] The one or more transducers 202 may be formed of a material capable of converting applied electrical pulses into pressure distortions on the surface of the one or more transducers 230, and vice versa. Examples of suitable materials include piezoelectric ceramic materials, piezoelectric composites, piezoelectric plastics, barium titanate, lead zirconate titanate, lead metaniobate, polyvinylidene fluoride, and the like. Other transducer technologies include composite materials, single crystal composite materials, and semiconductor devices (e.g., capacitive micromachined ultrasonic transducers ("cMUTs"), piezoelectric micromachined ultrasonic transducers ("pMUTs"), and the like).

[0057] The pressure distortion on the surface of the one or more transducers 202 forms an acoustic pulse of a certain frequency based on the resonant frequency of the one or more transducers 202. The resonant frequency of the one or more transducers 202 may be affected by the size, shape, and material used to form the one or more transducers 202. The one or more transducers 202 can be formed in any shape suitable for positioning within the IVUS catheter 104 and propagating an acoustic pulse of a desired frequency in one or more selected directions. For example, the transducer can be disc-shaped, block-shaped, rectangular, elliptical, etc. The one or more transducers can be formed in the desired shape by any process, including, for example, cutting, cutting and filling, machining, micro-fabrication, etc.

[0058] As an example, each of the one or more transducers 202 may include a layer of piezoelectric material sandwiched between a matching layer and a conductive backing material formed of an acoustically absorbent material (e.g., an epoxy substrate with tungsten particles). During operation, the piezoelectric layer can be electrically excited to emit acoustic pulses.

[0059] The one or more transducers 202 can be used to form radial cross-sectional images of the surrounding space. Thus, for example, when the one or more transducers 202 are disposed in the IVUS catheter 104 and inserted into a patient's blood vessel, the one or more transducers 202 can be used to capture acoustic signals for processing by the image acquisition device 102, and in particular, by the AFE described herein.

[0060] The imaging core 204 rotates about the longitudinal axis of the IVUS catheter 104. As the imaging core 204 rotates, the one or more transducers 202 transmit acoustic signals in different radial directions (e.g., along different radial scan lines). For example, the one or more transducers 202 may transmit acoustic signals in regular (or irregular) increments, such as 256 radial scan lines per revolution. It should be understood that other numbers of radial scan lines may be transmitted per revolution instead.

[0061] When a transmitted acoustic pulse of sufficient energy encounters one or more medium boundaries, such as one or more tissue boundaries, a portion of the transmitted acoustic pulse is reflected as an echo pulse to the transmitting transducer. Each echo pulse of sufficient energy to be detected that reaches the transducer is converted into an electrical signal in the receiving transducer. The one or more converted electrical signals are transmitted to the imaging processing circuitry 116 of the image acquisition device 102, where they are processed and digitized. The digitized signal can be transmitted to the computer subsystem 118 and used to form an image of the blood vessel, which can be displayed on the imaging subsystem 108. In some cases, the rotation of the imaging core 204 is driven by the MDU 106, which is itself controlled by other subsystems 120.

[0062] When one or more transducers 202 rotate about the longitudinal axis of the IVUS catheter 104 emitting acoustic pulses, multiple images can be formed that collectively form a radial cross-sectional image (e.g., a tomographic image) of a region surrounding the one or more transducers 202, such as a portion of the wall of a vessel of interest and the tissue surrounding the vessel. The imaging core 204 can also be moved longitudinally along the vessel into which the IVUS catheter 104 is inserted, so that multiple cross-sectional images can be formed along the longitudinal length of the vessel. During the imaging procedure, one or more transducers 202 can be retracted (e.g., pulled back) along the longitudinal length of the IVUS catheter 104. The IVUS catheter 104 can include at least one telescoping section that can be retracted during the retraction of one or more transducers 202. In some cases, the MDU 106 is driven to retract the imaging core 204 within the IVUS catheter 104. The distance that the MDU 106 retracts the imaging core 204 can be any suitable distance, including, for example, at least 5 cm, 10 cm, 15 cm, 20 cm, 25 cm, or more. The entire IVUS catheter 104 may be retracted during the imaging procedure, regardless of whether the imaging core 204 is longitudinally moved independently of the IVUS catheter 104 .

[0063] The quality of images generated by the one or more transducers 202 at different depths may be affected by one or more factors, including, for example, bandwidth, transducer focus, beam pattern, and the frequency of the acoustic pulses. The frequency of the acoustic pulses output from the one or more transducers 202 may also affect the penetration depth of the acoustic pulses output from the one or more transducers 202. Generally, as the frequency of the acoustic pulses decreases, the penetration depth of the acoustic pulses within the patient's tissue increases. In some cases, the intravascular therapy IVUS imaging system 100 operates in a frequency range of 5 MHz to 200 MHz.

[0064] One or more conductors 224 may electrically couple the transducer 202 and the catheter bus 112. In this manner, electrical signals captured by the transducer 202 may be received by the imaging processing circuitry 116 of the image acquisition device 102.

[0065] Figure 3 Show Figure 1 FIG2 illustrates an embodiment of the imaging processing circuit 116 of the IVUS imaging system 100. As can be seen from the figure, the imaging processing circuit 116 includes both an analog subsystem 302 and a digital subsystem 304. In addition, the analog subsystem 302 includes at least an analog front end (AFE) 306. The analog front end (AFE) 306 is coupled to the MDU 106 and receives signals originating from the IVUS catheter 104.

[0066] Figure 4An embodiment of the AFE 306 is shown. As shown, the AFE 306 includes several stages or blocks. In particular, the AFE 306 includes an input stage 500, a high-pass filter 600, a first gain stage 700, a second gain stage 800, and a low-pass filter and ADC driver 900. It is important to note that one advantage of the present invention, which will be described in more detail below, is that each stage or block of the AFE 306 includes multiple paths to accommodate imaging devices of various bandwidths (e.g., traditional IVUS devices, next-generation IVUS devices, etc.). These paths can be dynamically controlled or set at the time of manufacturing. However, it should be noted that there is no need to redesign the AFE 306 or manufacture new circuit boards to support changes in the imaging devices supported by the AFE 306.

[0067] Figure 5 A circuit diagram of one embodiment of an input stage 500 of the AFE 306 is shown. In some embodiments, the AFE 306 may include one or more signal paths to acquire a return signal from the IVUS catheter 104 (e.g., a return signal captured by the transducer 202 and transmitted to the MDU 106). For example, the input stage 500 may include a first connector 502, a second connector 504, or both the first connector 502 and the second connector 504. In some embodiments, the first connector 502 may be a Lemo connector configured to couple to an RF signal line (e.g., the MDU bus 110, etc.). In some embodiments, the second connector 504 may be a sub-micron version A (SMA) connector configured to couple to an RF signal line (e.g., the MDU bus 110, etc.). Where more than one connector is provided in the input stage 500 (e.g., the first connector 502, the second connector 504, etc.), the input stage 500 may include a switch 506 to switch between the first connector 502 and the second connector 504. It should be noted that in some examples, input stage 500 may include multiple connectors to allow test engineers flexibility in testing AFE 306 without custom cable assemblies or fixtures, but rather utilizing off-the-shelf cables (eg, SMA connectors, etc.).

[0068] Input stage 500 also includes a transient voltage suppression diode, such as a TVS diode 508. In some embodiments, TVS diode 508 may be a low capacitance TVS diode and may be included in input stage 500 to reduce the risk of electrostatic discharge.

[0069] Figure 6A circuit diagram of one embodiment of a high-pass filter 600 of the AFE 306 is shown. The high-pass filter 600 includes a switch 602, which can be controlled by, for example, another subsystem 120 of the image acquisition device 102. The switch 602 can be used to select between a high-pass filter 604 and a high-pass filter 606 in the high-pass filter 600. The high-pass filter 600 is provided with two high-pass filters having different characteristics. As shown, the high-pass filter 604 is a 5 megahertz (MHz) filter having two 620 picofarad (pF) capacitors 608a and 608b and an 820 nanohenry (nH) inductor 610. Conversely, the high-pass filter 606 is a 20 MHz filter having two 160 pF capacitors 612a and 612b and an 820 nH inductor 614.

[0070] In some examples, high pass filter 604 may be a 0 MHz (short-circuited to pass the signal unfiltered) to 12 MHz high pass filter, and high pass filter 606 may be a 15 to 30 MHz high pass filter.

[0071] As described above, the high-pass filter 600 stage of the AFE 306 includes multiple "paths" (e.g., a first path through the high-pass filter 604, a second path through the high-pass filter 606, etc.), which are selected by the switch 602. Furthermore, as described above, the switch 602 can be coupled to and / or controlled by other subsystems 120 (e.g., an FPGA of the other subsystem 120, etc.) and dynamically adjusted to change the selected path based on the type of imaging device (e.g., IVUS catheter 104) coupled to the MDU 106. As an example, if the IVUS catheter 104 is a conventional (or lower bandwidth) IVUS catheter, the switch 602 can be configured (e.g., by the other subsystem 120) to select the high-pass filter 604, while if the IVUS catheter 104 is a next-generation (or higher bandwidth) IVUS catheter, the switch 602 can be configured (e.g., by the other subsystem 120) to select the high-pass filter 606.

[0072] Figure 7A 、 Figure 7B 、 Figure 7C and Figure 7D FIG3 shows one embodiment of a portion of a first gain stage 700 of the AFE 306. Before describing these figures in more detail, a general overview of the first gain stage 700 is provided. Typically, a signal originating from the high pass filter 600 passes through one of two attenuators (e.g., Figure 7A The voltage controlled attenuator is configured by other subsystems 120, wherein the signal is fed to a transimpedance amplifier (e.g., Figure 7B From the attenuator stage, the signal travels through one of two high-speed op amps (e.g., Figure 7C), and then passes through one of two radio frequency (RF) attenuators (e.g., Figure 7D ). It should be noted that Figure 7D The RF attenuator depicted in the Figure 7A and Figure 7B Controlled in the same manner as the attenuator shown in .

[0073] More specifically turning Figure 7A , a circuit 702 is shown in which a pair of voltage attenuators (e.g., voltage attenuator 704 and voltage attenuator controller 706) are depicted. The portion of the first gain stage 700 depicted here receives an RF signal originating from the high pass filter 600 at input 708. The signal is routed through either the voltage attenuator 704 or the voltage attenuator controller 706. The voltage attenuator through which the signal is routed can be set during manufacturing by soldering a jumper (e.g., a 0 ohm (Ω) resistor) across any of the path resistors 710a, 710b, and 710c to select the voltage attenuator 704 or across the path resistors 712a and 712b to select the voltage attenuator controller 706. The signal is then passed (e.g., at terminal 714) to Figure 7C 700 is shown. It should be noted that the term "path resistor" is used interchangeably herein with jumpers and jumper positions. That is, the term jumper position is intended to refer to the location of the path resistors (e.g., path resistor 710a, etc.) outlined herein, while jumpers are intended to refer to where an electrical conductor (e.g., a 0Ω resistor, a wire, etc.) is installed at the jumper location. It should be understood that the path resistor locations described herein will not all be installed, but rather are provided to facilitate flexibility in selecting which subcircuits are "active," or more precisely, which circuits are connected and not connected to the inputs and outputs of each stage.

[0074] Figure 7B A schematic diagram illustrating one embodiment of a control circuit for the voltage attenuators 704 and 706 of the first gain stage 700 is shown. As shown, the control sides of the voltage attenuators 704 and 706 are coupled to terminal 716, and either the path resistor 710b or the path resistor 712b is mounted at Figure 7A , to complete the circuit to one of the voltage attenuators 704 or 706. The control signal may be generated by other subsystems 120 (e.g., FPGA of other subsystems 120, etc.) and passed through the circuit, such as Figure 7B The circuit depicted in is routed to terminal 716. Figure 7BCircuit 718 is shown, which receives as input a digital control signal (e.g., a 12-bit double data rate (DDR) control signal, etc.) originating from other subsystems 120 at a DAC input 720. The digital signal received at the DAC input 720 is fed through a digital-to-analog converter and then fed to a conditioning circuit 724 and a conditioning circuit 726. The conditioning circuit 724 and the conditioning circuit 726 each include an op amp and a resistor-capacitor (RC) circuit operating as a transimpedance amplifier. The outputs from the conditioning circuit 724 and the conditioning circuit 726 are routed to terminal 716.

[0075] Figure 7C One embodiment of a pair of high speed op amps is shown depicted as circuit 728. Circuit 728 is configured to receive signals from Figure 7A 702 of the circuit 702. Circuit 728 has as input terminal 714, and then a path through one of a plurality of amplifier circuits (e.g., op amp circuit 730 or op amp circuit 732). The amplifier circuit through which the RF signal originating from terminal 714 is routed can be set at the time of manufacture by installing a jumper (e.g., a 0Ω resistor) in path resistor 734 or path resistor 736. The output from the set amplifier stage (e.g., op amp circuit 730, op amp circuit 732, etc.) is available at terminal 738, which feeds Figure 7D In circuit 740.

[0076] Figure 7D shows a circuit 740 which is similar to Figure 7A Another voltage attenuator circuit of circuit 702. Circuit 740 includes voltage attenuators 742 and 744, which can be selected based on the installation jumpers (e.g., at path resistors 746a, 746b, and 746c or path resistors 748a and 748b) as described above with respect to circuit 702. In addition, although not shown here, circuit 740 can be used in the same manner and with the same Figure 7B 7. The same type of circuitry shown in FIG. 7 (eg, circuit 718) is used for control.

[0077] The second gain stage 800 can be electrically coupled to the output of the first gain stage 700. Typically, the second gain stage 800 includes a pair of amplifier circuits (e.g., Figure 8A ) (the circuit can be completed by this pair of amplifier circuits during manufacture) and the subsequent limiting amplifier stage (e.g. Figure 8B ). For example, Figure 8AAs shown, circuit 802 includes amplifier circuit 804 and amplifier circuit 806, which correspond to alternative electrical paths through circuit 802. This path is set during manufacturing by installing jumpers (e.g., 0Ω resistors, etc.) in path resistors 808a and 808b or path resistors 810a and 810b. Amplifier circuits 804 and 806 each include an op amp configured to amplify RF signals by different amounts. Circuit 802 has an output at terminal 812, which is an input to circuit 814.

[0078] Figure 8B One embodiment of a limiter circuit 814 is shown that receives an input from circuit 802 at terminal 812 and includes an op amp arranged in a limiter configuration.

[0079] Figure 9 A circuit diagram of a circuit 902 of a low-pass filter and ADC driver 900 of the AFE 306 is shown in accordance with some embodiments. The low-pass filter and ADC driver 900 includes a switch 904, which can be controlled, for example, by other subsystems 120 of the image acquisition device 102. The switch circuit 902 can be used to select between a low-pass filter 906 and a low-pass filter 908 of the low-pass filter and ADC driver 900. The low-pass filter and ADC driver 900 is provided with two low-pass filters having different characteristics. As shown, the low-pass filter 906 is a 45 megahertz (MHz) filter, while the low-pass filter 908 is an 88 MHz filter.

[0080] As with the high-pass filter 600 stage of the AFE 306, the low-pass filter and ADC driver 900 includes multiple "paths" (e.g., a first path through the low-pass filter 906, a second path through the low-pass filter 908, etc.), which are selected by the switch 904. Furthermore, as described above, the switch 904 can be coupled to and / or controlled by other subsystems 120 (e.g., an FPGA of the other subsystem 120, etc.) and dynamically adjusted to change the selected path based on the type of imaging device (e.g., IVUS catheter 104) coupled to the MDU 106. As an example, if the IVUS catheter 104 is a conventional (or lower bandwidth) IVUS catheter, the switch 904 can be configured (e.g., by the other subsystem 120) to select the low-pass filter 906, while if the IVUS catheter 104 is a next-generation (or higher bandwidth) IVUS catheter, the switch 904 can be configured (e.g., by the other subsystem 120) to select the low-pass filter 908.

[0081] Based on the output of low-pass filter 906 or low-pass filter 908, circuit 902 includes multiple analog-to-digital converter (ADC) drivers, which can be selected during manufacturing by installing a jumper (e.g., a 0Ω resistor, etc.) in path resistor 910 or path resistor 912 to complete the circuit path through ADC driver 914 or ADC driver 916.

[0082] In some embodiments, the sampling frequency of ADC driver 914 and / or ADC driver 916 can be 400 megasamples / second (MSPS), which can be 4.5 times the maximum frequency of the sampled signal. Thus, oversampling in this manner can eliminate the need for an anti-aliasing filter. Some embodiments can provide a dynamically selectable anti-aliasing filter.

[0083] It should be noted that the choice of which ADC driver to use can be based on the bandwidth of the sampled signal (e.g., legacy, next-generation, etc.). For example, both ADC driver 914 and ADC driver 916 are capable of processing RF signals, but each has unique advantages over the other. For example, ADC driver 914 may provide faster overdrive recovery (e.g., 1 nanosecond, etc.), which allows the system to better handle saturated signals (e.g., when plaque is detected). As another example, ADC driver 916 provides lower distortion and lower noise, and therefore should produce a clearer image than ADC driver 914.

[0084] Figure 10 FIG1 shows a circuit diagram of an AFE 1000, which can be implemented as AFE 306. As shown, AFE 1000 includes multiple sub-stages or blocks. AFE 1000 includes an input stage 1002, a high-pass filter 1004, a gain stage 1006, a gain stage 1008, a gain stage controller 1010, a low-pass filter 1012, and an ADC 1014. In some embodiments, gain stage 1006 and gain stage 1008 can be combined into a single gain stage. In some examples, input stage 1002 can be similar to Figure 5 The input stage 500 shown in FIG; the high pass filter 1004 may be similar to Figure 6 The high pass filter 600 shown in FIG; the gain stage 1006 and the gain stage controller 1010 may be similar to Figure 7A 、 Figure 7B 、 Figure 7C and Figure 7D The first gain stage 700 shown in FIG; the gain stage 1008 may be similar to Figure 8A and Figure 8B The second gain stage 800 shown in FIG; and the low pass filter 1012 and ADC 1014 may be similar to Figure 9 The low pass filter and ADC driver 900 are shown in FIG.

[0085] Terms used herein should be given their ordinary meaning in the relevant art or the meaning indicated by their usage in the context, but if an explicit definition is provided, that meaning shall prevail.

[0086] Herein, references to "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment, although they may refer to the same embodiment. Unless the context clearly requires otherwise, throughout the specification and claims, the words "comprises," "comprising," and the like should be interpreted as inclusive, and not exclusive or exhaustive; that is, as "including but not limited to." Words using the singular or plural number also include the plural or singular, respectively, unless expressly limited to one or more. Additionally, the words "herein," "above," "below," and words of similar meaning, when used in this application, refer to the application as a whole and not to any part of this application. When a claim uses the word "or" to refer to a list of two or more items, the word covers all of the following interpretations of the word: any one of the items in the list, all of the items in the list, and any combination of the items in the list, unless expressly limited to one or the other. Any term not expressly defined herein has the conventional meaning commonly understood by those skilled in the relevant art.

Claims

1. An analog front end (AFE) for an in-vivo image acquisition device, comprising: a high pass filter stage comprising a plurality of high pass filters and at least one switch selectable to electrically couple one of the plurality of high pass filters to an input; a gain stage, the gain stage comprising: Multiple voltage attenuators, multiple amplifier circuits, and a plurality of jumper positions, wherein one or more jumpers are installed in at least one, but not all, of the plurality of jumper positions to electrically couple one of the plurality of voltage attenuators to an output from the high pass filter stage and to electrically couple the output from the one of the plurality of voltage attenuators to one of the plurality of amplifier circuits; as well as A low pass filter stage includes a plurality of low pass filters and at least one switch selectable to electrically couple one of the plurality of low pass filters to an output from the gain stage. 2 . The AFE of claim 1 , wherein the plurality of high-pass filters comprises a first high-pass filter and a second high-pass filter, wherein the first high-pass filter is a 0 to 12 MHz high-pass filter, and wherein the second high-pass filter is a 15 to 30 MHz high-pass filter.

3. The AFE of claim 2 , wherein the at least one switch of the high-pass filter stage comprises a first switch and a second switch, and wherein the first switch and the second switch are configured to be dynamically controlled by a controller circuit and arranged to electrically couple the input to the analog front end to a selected one of the first high-pass filter or the second high-pass filter, and to electrically couple the output from the selected one of the first high-pass filter or the second high-pass filter to the output of the high-pass filter stage.

4. The AFE according to claim 2 , wherein the first high-pass filter and the second high-pass filter are T-type high-pass filters including a pair of capacitors arranged in series and an inductor electrically coupled between a ground terminal and a center of the pair of capacitors.

5. The AFE according to any one of claims 1 to 4, wherein the plurality of voltage attenuators of the gain stage comprises a first voltage attenuator and a second voltage attenuator, wherein the first voltage attenuator is a 12 dB voltage attenuator, and wherein the second voltage attenuator is a 28 dB voltage attenuator. 6 . The AFE of claim 5 , wherein the gain stage further comprises a digital-to-analog converter and at least one transimpedance amplifier, wherein the transimpedance amplifier is electrically coupled to a control input of the first voltage attenuator or the second voltage attenuator based on the one or more jumpers.

7. The AFE of claim 5 , wherein the plurality of amplifier circuits include a first amplifier circuit and a second amplifier circuit, wherein the first amplifier circuit includes an inductor, an operational amplifier (op amp), and a plurality of resistors arranged to form an amplifier circuit, and wherein the second amplifier circuit includes an op amp and a plurality of resistors arranged to form an amplifier circuit.

8. The AFE according to any one of claims 1 to 7, wherein the plurality of voltage attenuators include a first pair of voltage attenuators and a second pair of voltage attenuators, and wherein one of the amplifier circuits is electrically coupled between the first one of the first pair of voltage attenuators and the first one of the second pair of voltage attenuators based on the one or more jumpers.

9. The AFE according to any one of claims 1 to 8, wherein the gain stage comprises a first gain stage and a second gain stage, wherein the second gain stage comprises a limiting operational amplifier (op amp).

10. The AFE of claim 9 , wherein the second gain stage further comprises a first amplifier circuit, a second amplifier circuit, and a plurality of pairs of jumper positions, wherein a pair of jumpers is installed in one of the plurality of pairs of jumper positions to electrically couple an input to the second gain stage to a selected one of the first amplifier or the second amplifier, and to electrically couple the output of the selected one of the first amplifier or the second amplifier to the limiting op amp.

11. The AFE according to any one of claims 1 to 10, wherein the plurality of low-pass filters comprises a first low-pass filter and a second low-pass filter, wherein the first low-pass filter is a low-pass filter less than or equal to 60 MHz, and wherein the second low-pass filter is a low-pass filter greater than 60 MHz.

12. The AFE according to any one of claims 1 to 10, comprising at least one analog-to-digital converter (ADC) driver.

13. An in-vivo image acquisition device comprising an image acquisition circuit and a digital processing circuit, the image acquisition circuit comprising the AFE according to any one of the preceding claims, and the digital processing circuit being arranged to receive a digitized signal originating from the AFE and generate an image.

14. The in-vivo image acquisition device of claim 13, comprising a motor drive unit (MDU) coupled to the image acquisition circuit.

15. The in-vivo image acquisition device of claim 13, comprising an intravascular ultrasound catheter coupled to the MDU.

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