Inductive displacement transducer system with impedance switching section

Abstract

An inductive displacement transmitter system is provided, comprising an inductive displacement transmitter and one or more sensing circuit sections. Each sensing circuit section is connected to a first and a second sensing coil terminal and configured to receive a signal from a respective sensing coil. It includes an impedance circuit section and an input circuit section (e.g., of an ASIC). The impedance circuit section comprises at least a first and a second impedance circuit component. The first impedance circuit component is coupled between the first and second impedance circuit nodes.The second impedance circuit section component is at least one of: coupled between the first coil terminal and the first impedance circuit section node; or coupled between the first impedance circuit section node and the second impedance circuit section node (where in some implementations a third impedance circuit section component may also be provided).

Description

GENERAL STATE OF THE TECHNOLOGYTECHNICAL FIELD

[0001] This disclosure relates to measurement technology and in particular to inductive position measuring transducers. DESCRIPTION OF THE STATE OF THE ART

[0002] Inductive displacement transducer systems can be used to measure relative displacements between one or more sensing coils (which, for example, may alternatively be referred to as receiver coils or receiver windings) and one or more signal modulation elements (e.g., scale elements) that modulate the inductive coupling between the sensing coils and a field-generating coil (which, for example, may alternatively be referred to as a transmitter coil). In various conventional inductive displacement transducer systems (e.g., as disclosed in U.S. Patents 6,005,387 and 6,011,389, each of which is hereby incorporated by reference in its entirety), a relatively low-power intermittent drive circuit is used to deliver a time-varying drive signal at an operating frequency to the frequency-generating coils.

[0003] An example of an inductive displacement transducer system using high-precision measurement techniques is described in U.S. Patent 5,901,458, which is hereby incorporated by reference in its entirety. As described in the '458 patent, the inductive displacement transducer system includes a reduced-displacement displacement transducer that uses a read head that is movable along a scale. Electronics provide a precise measurement of the position of the read head on the scale. Another example is described in U.S. Patent 5,886,519, which is hereby incorporated by reference in its entirety. The '519 patent describes an absolute inductive displacement transducer system for high-precision applications, such as linear or rotary encoders, electronic calipers, and the like. The inductive displacement transducer system uses two relatively movable elements. The first element contains at least one active field generating coil (e.g.a transmitter coil) for generating a magnetic field and at least one sensing coil (e.g., a receiver coil) for receiving the generated magnetic field. The passive second element (e.g., a scale element) includes passive signal modulation elements that modulate the received field depending on their position relative to the at least one sensing coil. An electronic circuit coupled to the at least one field-generating coil and the at least one sensing coil compares the outputs of the at least one sensing coil, evaluates the absolute position between the two elements, and provides the determined absolute position on a display.

[0004] While such inductive position transducer systems can be used to determine the position between two elements, in some applications it may be desirable to improve the levels and / or processing of the signals from the sensing coils. An inductive position transducer system with improved characteristics would be desirable. SUMMARY

[0005] This Summary is provided to introduce, in a simplified form, a selection of concepts that are further described below in the Detailed Description. This Summary is not intended to identify key features of the claimed subject matter, nor is it intended to be an aid in determining the scope of the claimed subject matter.

[0006] An inductive displacement transducer system is provided that includes an inductive displacement transducer and a sensing circuit portion. The inductive displacement transducer comprises a first sensing coil portion (e.g., having a first sensing coil) with a first coil terminal, a second coil terminal, and a coil impedance. The sensing circuit portion is configured to receive a first sensing coil signal from the first sensing coil portion. The sensing circuit portion includes an impedance circuit portion and an input circuit portion (e.g., an application-specific integrated circuit (ASIC)).

[0007] The impedance circuit section is connected to the first and second coil terminals. The impedance circuit section includes a first impedance circuit section component and a second impedance circuit section component. The first impedance circuit section component is coupled between a first impedance circuit section node and a second impedance circuit section node. The second impedance circuit section component is at least one of: coupled between the first impedance circuit section node and the second impedance circuit section node; or coupled between the first coil terminal and the first impedance circuit section node.

[0008] The input circuit section (e.g., of the ASIC) is connected to the first and second impedance circuit section nodes. The input circuit section has an input impedance during operation (e.g., while an operating frequency is utilized), wherein the input circuit section is configured to receive an oscillating sense signal at the first and second impedance circuit section nodes. A combined impedance section, comprising at least the impedance circuit section and the first sense coil section, has a combined impedance during operation, which is presented to the input circuit section (e.g., of the ASIC). In various implementations, the components of the impedance circuit section can be selected / configured such that the combined impedance is approximately matched to the input impedance of the input circuit section or at least approximately matched (e.g.,compared to the impedance of the sense coil section alone, which is otherwise typically not well matched to the input impedance of the input circuit section).

[0009] According to another aspect, a method is provided for operating an inductive displacement transducer system comprising at least one scale element, a first field-generating coil portion, and at least one first sensing coil portion (e.g., having a first sensing coil) with a first coil terminal, a second coil terminal, and a coil impedance. The method includes: providing a drive signal having an operating frequency to the first field-generating coil portion for generating a changing magnetic flux surrounding at least a portion of the first sensing coil portion; and receiving a first sensing coil signal from the first sensing coil portion at the sensing circuit portion indicative of a relative position between the first sensing coil portion and the scale element. The sensing circuit portion includes the impedance circuit portion and the input circuit portion.In various implementations, the method may further include determining a relative position between the first sense coil portion and the scale element (e.g., corresponding to a relative position between a read head and the scale element) based at least in part on the received oscillating sense signal at the first and second impedance circuit portion nodes.

[0010] According to a further aspect, the sensing circuit section is intended for inclusion in an inductive position transducer system. The sensing circuit section comprises the impedance circuit section and the input circuit section. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram of an inductive position transducer system. Fig. 2 is a block diagram of a more specific implementation of an inductive position transducer system such as that of Fig. 1. Fig. 3 is a diagram of a sensing coil circuit logic portion of an inductive position transducer system such as that of the Fig. 1 and Fig. 2. The Fig. 4A-4C are diagrams of implementations of the sense coil circuit logic portion of Fig. 3, including a first impedance circuit section component coupled between a first impedance circuit section node and a second impedance circuit section node, and including a second impedance circuit section component coupled between a first coil terminal and the first impedance circuit section node. The Fig. 5A and Fig. 5B are diagrams of implementations of the sense coil circuit logic portion of Fig. 3, including a first impedance circuit section component coupled between a first impedance circuit section node and a second impedance circuit section node, and including a second impedance circuit section component coupled in parallel to the first impedance circuit section component. The Fig. 6A and Fig. 6B are diagrams of implementations of the sense coil circuit logic portion of Fig. 3, including a first impedance circuit section component coupled between a first impedance circuit section node and a second impedance circuit section node, and including a second impedance circuit section component coupled in parallel to the first impedance circuit section component, and including a third impedance circuit section component coupled between a first coil terminal and the first impedance circuit section node. The Fig. 7A-7D are diagrams of Smith charts used to determine the elements of impedance circuit sections such as those of Fig. 4A-4C, 5A-5B and 6A-6B can be used. Fig. Figure 8 is a flowchart illustrating an example routine for operating an inductive position transducer system. DETAILED DESCRIPTION

[0011] Fig. 1 is a block diagram of an inductive position transducer system 10. As shown in Fig. 1, the inductive position transducer system 10 includes multi-signal transducer and driver / sense circuitry 12 that outputs differential analog signals on signal lines 12A and 12B to an analog signal processor 70. The analog signal processor 70 outputs differential signals on signal lines 70A and 70B to a ramp analog-to-digital converter 80. The ramp analog-to-digital converter 80 outputs digital values ​​to a logic circuit 90 via a data line 80A. The logic circuit 90 supplies and receives signals from a control unit 60 via a data and power bus 90A.

[0012] The control unit 60 also provides control signals over a data and power bus 60A to the multi-signal converter and driver / sense circuitry 12, control signals over a data and power bus 60B to the analog signal processor 70, and control signals over a data and power bus 60C to the ramp analog-to-digital converter 80. A low-voltage power supply 50 can power the entire inductive position transducer system 10 over one or more power supply lines 50A, with the power then being further distributed over the various data and power buses of the system and subject to control by the digital control unit 60. Further details regarding the operations and processing of an inductive position transducer system similar to that of Fig. 1 are described in US Patent 6,859,762, which is hereby incorporated by reference in its entirety.

[0013] While Fig. While Figure 1 shows a functional block diagram for the inductive position transducer system 10, it should be understood that the inductive position transducer system 10 is presented as an exemplary embodiment. It should be understood that the transducer may be implemented in the circuit logic 12 using any suitable known or later developed multi-signal transducer, including, for example, the transducers described in the incorporated '458 and '519 patents.

[0014] Fig. 2 is a block diagram of a more specific implementation of an inductive position transducer system 100, which is an implementation of the system of Fig. 1. The inductive displacement transducer system 100 includes an inductive displacement transducer 108 comprising field-generating coil sections including AC field-generating coils, a scale element 110, and sensing coil sections 120-n including sensing coils, as described in more detail below. In one implementation, multiple three-phase transducer coils are used. Fig. Figure 2 shows an example of a three-scale track design in which three sets of three-phase sensing coils are present. An example of a three-scale track design is further described in U.S. Patent 6,304,832, which is hereby incorporated by reference in its entirety.

[0015] As in Fig. 2, the inductive displacement transducer system 100 includes a field generating coil section 122 (e.g., comprising a field generating coil A) connected to a driver circuit 152. The first, second, and third sensing coil sections 120-A1, 120-A2, and 120-A3 include first, second, and third sensing coils 124, 126, and 127, respectively. The field-generating coil A of the field-generating coil section 122 is indirectly inductively coupled to the first, second, and third sensing coils 124, 126, and 127 of the first, second, and third sensing coil sections 120-A1, 120-A2, and 120-A3 via signal modulation elements (e.g., comprising conductive plates or coupling loops, etc.) formed on the scale element 110 of the inductive displacement transducer 108.

[0016] According to the principles disclosed herein, each of the first, second, and third sense coil sections 120-A1, 120-A2, and 120-A3 is coupled to a first, a second, and a third impedance circuit section 130-A1, 130-A2, and 130-A3, respectively. More generally, each of the sense coil sections 120-n of the inductive displacement transducer 108 is coupled to a respective impedance circuit section 130-n. As described in more detail below (e.g., with respect to the Fig. 3-8), the inclusion of impedance circuit sections may result in certain desirable features (e.g., an increase in the signal available to input circuit sections, etc.). In various implementations, input circuit sections (e.g., as described in more detail below with respect to Fig. 3, etc.) coupled to the impedance circuit sections 130-n may be included in a section of the circuit logic following the impedance circuit sections (e.g., in one of the circuit sections 155, 170, etc., described in more detail below).

[0017] As in Fig. 2, the first, second, and third impedance circuit sections 130-A1, 130-A2, and 130-A3 are coupled to a multiplexer 155 (which, for example, as noted above, may include one or more respective input circuit sections in certain implementations, or for which one or more respective input circuit sections may alternatively be included in subsequent circuit logic). A differential output of the multiplexer 155 is connected to an analog signal processor 170 via lines 155A and 155B. The differential output of the analog signal processor 170 is provided to an input of an analog-to-digital converter 180 via six output lines 170A through 170F. The analog-to-digital converter 180 converts the differential output of the analog signal processor 170 from an analog signal to a digital signal.The digital signal from the analog-to-digital converter 180 is output via a line 180A to the logic circuit 190, which processes the digital signal from the analog-to-digital converter 180 to determine the relative position between the read head (which includes, for example, the field-generating coil sections and the sensing coil sections) and the scale element 110.

[0018] Positions within a wavelength can be uniquely identified by logic circuit 190 according to known techniques and equations (such as those disclosed in the incorporated '458 and '519 patents). Logic circuit 190 also controls the sequence of signal sampling by outputting a control signal over signal lines 190A-190D to a digital control unit 160. Digital control unit 160 controls the sequence of transmission, signal sampling, and analog-to-digital conversion by outputting control signals on power and signal bus lines 160A-160I to drivers 152-154, multiplexer 155, analog signal processor 170, and ramp analog-to-digital converter 180.

[0019] In particular, the digital control unit 160, as shown in Fig. 2, control signals are output to drivers 152-154 via power and signal bus lines 160A-160C, respectively, to controllably energize the field-generating coils AC (i.e., where field-generating coil section 122 includes field-generating coil A). Digital control unit 160 also outputs switching and control signals to multiplexer 155 via power and signal bus lines 160D-160F. In various implementations, the control signals on lines 160D-160F determine which of the possible phases of multi-scale track multi-phase sensing coils 124, 126, and 127 are input to analog signal processing circuits 170 following multiplexer 155.A low-voltage power supply 150 may power the entire inductive position transducer system 100 via one or more 150A power supply lines, which power is then distributed via the various data and power buses of the system and is subject to control by the digital control unit 160.

[0020] As mentioned above, Fig. 2 shows an example of a three-scale track design in which three sets of three-phase sense coils are present. In various implementations, multiplexer 155 can select a signal, or in the case of differential measurements, a signal pair, to be output to analog signal processor 170. The selected signal or signal pair is then processed by analog signal processor 170. Analog signal processor 170 is controlled by the control signals on lines 160G and 160H. The output of analog signal processor 170 is provided on signal lines 170A-170F, which serve as input to analog-to-digital converter 180. Analog-to-digital converter 180 is controlled by the control signals on line 160I. Logic circuitry 190 can access the output of analog-to-digital converter 180.In addition, since the logic circuit 190 controls the operation of the digital control unit 160, the logic circuit 190 can select the scale paths or phases in any order.

[0021] As described in more detail in US Patent 6,304,832, which is hereby incorporated by reference in its entirety, an embodiment similar to the above describing signal multiplexing between the multiple phases of a single set of sensing coils is equally applicable to multiplexing between the multiple phases of two or more sets of multiphase sensing coils. For example, in a three-scale railway system, as in Fig. As shown in Figure 2, the input multiplexer 155 can select between nine possible phase pairs for processing. To compensate for certain circuit errors, it can also select these phase pairs in a reversed polarity mode, effectively inverting the signal. Thus, in various implementations, there can be a total of 18 ways to process the nine phase pairs of a three-scale three-phase system.

[0022] Fig. 3 is a diagram of a sensing coil circuit logic portion 300 of an inductive position transducer system such as that shown in FIGS. Fig. 1 and Fig. 2. As in Fig. 3, the sense coil circuit logic section 300 includes a sense coil section 320, an impedance circuit section 330, and an input circuit section 340 (which may, for example, each be an implementation of a sense coil section 120-n, an impedance circuit section 130-n, and an input circuit section, respectively, as described above with reference to Fig. 2). The detection coil section 320 (e.g., including a detection coil) has a first coil terminal 321 and a second coil terminal 322. The detection coil section 320 also has a coil impedance (e.g., a coil impedance Z Rx , as described in more detail below).

[0023] A sensing circuit section SCP includes the impedance circuit section 330 and the input circuit section 340. The sensing circuit section SCP is coupled to the sensing coil section 320 and configured to receive a sensing coil signal from the sensing coil section 320 (e.g., in the implementation of Fig. 2, each sensing coil section 120-n may be coupled to a respective sensing circuit section. The impedance circuit section 330 is connected to the first and second coil terminals 321 and 322 and has first and second impedance circuit section nodes 331 and 332. The input circuit section 340 is connected to the first and second impedance circuit section nodes 331 and 332 and has an input impedance during operation (where the input impedance may, for example, correspond to an impedance of a termination resistor RT of the input circuit section 340, as described in more detail below).

[0024] The input circuit section 340 is configured to receive an oscillating sense signal (e.g., resulting from the first sense coil signal from the first sense coil section 320 as it passes through the impedance circuit section 330) at the first and second impedance circuit section nodes 331 and 332. In various implementations, the input circuit section 340 may represent an input section of additional circuitry of the inductive displacement transducer system (e.g., as described above with respect to Fig. 2, and wherein in certain implementations, the additional circuitry may be included in an application-specific integrated circuit (ASIC), wherein the input circuit portion 340 may represent an input portion of the ASIC).

[0025] As in Fig. 3, a combined impedance section CIP includes at least the first sense coil section 320 and the impedance circuit section 330 and, during operation, has a combined impedance presented to the input circuit section 340. In various implementations, the components of the impedance circuit section 330 can be selected such that the combined impedance is approximately matched to, or at least approximately matches, the input impedance of the input circuit section 340 (e.g., compared to the impedance of the sense coil section 320 alone, which is otherwise typically not well matched to the input impedance of the input circuit section 340). As described in more detail below, the Fig. 4A-4C, 5A-5B, and 6A-6B illustrate various examples of components that may be included in the impedance circuit section 330. Furthermore, certain exemplary techniques for determining / selecting the corresponding components are described below with respect to the Fig. 7A-7D are described in more detail.

[0026] The Fig. 4A-4C are diagrams of implementations of the sense coil circuit logic portion of Fig. 3. It is understood that the above-mentioned provisions in relation to Fig. 3 described properties and operations also for the implementations of the Fig. 4A-4C apply unless otherwise stated below. As described in Fig. As illustrated in Figure 4A, a sense coil circuit logic section 300' includes a first sense coil section 320, an impedance circuit section 330', and an input circuit section 340. The first sense coil section 320 (e.g., including a first sense coil CL1) has a first coil terminal 321, a second coil terminal 322, and a coil impedance (e.g., as described in more detail below).

[0027] A sensing circuit section SCP' is configured to receive a first sensing coil signal from the first sensing coil section 320. The sensing circuit section SCP' includes the impedance circuit section 330' and the input circuit section 340. The impedance circuit section 330' is connected to the first and second coil terminals 321 and 322. The impedance circuit section 330' includes a first impedance circuit section component Z1 and a second impedance circuit section component Z2. The first impedance circuit section component Z1 is coupled between a first impedance circuit section node 331 and a second impedance circuit section node 332. The second impedance circuit section component Z2 is coupled between the first coil terminal 321 and the first impedance circuit section node 331.

[0028] The input circuit section 340 is connected to the first and second impedance circuit section nodes 331 and 332. The input circuit section 340 has an input impedance during operation. In various implementations, the input impedance may correspond to the impedance of an input circuit section component ZT (which may be, for example, a termination resistor RT, as described in more detail below). As illustrated, the first impedance circuit section component Z1 is coupled in parallel to the input circuit section component ZT, with the components each effectively coupled between the first impedance circuit section node 331 and the second impedance circuit section node 332.The input circuit section 340 is configured to receive an oscillating sense signal (resulting, for example, from the first sense coil signal from the first sense coil section 320 as it passes through the impedance circuit section 330') at the first and second impedance circuit section nodes 331 and 332. A combined impedance section CIP' includes at least the impedance circuit section 330' and the first sense coil section 320 and, during operation, has a combined impedance presented to the input circuit section 340.

[0029] The Fig. 4B and Fig. 4C are more specific implementations of the sense coil circuit logic section 300' of Fig. 4A. Fig. 4B shows a sense coil circuit logic section 300A' and Fig. 4C shows a sense coil circuit logic section 300B'. As shown in the Fig. 4B and Fig. 4C, the sensing coil portion 320 includes inductance and resistance (e.g., of the sensing coil CL1), depicted as an inductive portion 323 and a resistive portion 324. Accordingly, a coil impedance Z Rx (e.g., the detection coil CL1) of the detection coil section 320, the inductance of the inductive section 323 and the resistance of the resistive section 324. As shown in the Fig. 4B and Fig. 4C further illustrates, in the input circuit section 340, the input circuit section component ZT is a terminating resistor RT.

[0030] A voltage V S of the sensing coil section 320 corresponds to the signal induced in the sensing coil CL 1 by the operations of the inductive position transducer system (e.g., as described above with respect to the Fig. 1 and Fig. 2). More specifically, a drive signal having an operating frequency is applied to a first field-generating coil section (e.g., including a first field-generating coil, such as the field-generating coil 122 of Fig. 2) is provided to generate a changing magnetic flux surrounding at least a portion of the first sensing coil section 320 (i.e., including the first sensing coil CL1, which in one example is the sensing coil 124 of Fig. 2). In various implementations, the voltage V Sa first sensing coil signal resulting from the changing magnetic flux inducing current in the first sensing coil portion 320 (e.g., as modified by signal modulation elements of the scale element to varying degrees depending on the relative position along the scale element), and wherein the first sensing coil signal correspondingly represents a relative position between the first sensing coil portion 320 and the scale element, such as the scale element 110 of Fig. 2, of the inductive position transducer system). A voltage V L of the input circuit section 340 corresponds to the respective signal that results (e.g., across the termination resistor RT). In various implementations, the voltage V Lan oscillating detection signal at the first and second impedance circuit section nodes 331 and 332 (resulting, for example, from the first detection coil signal from the first detection coil section 320 as it passes through the impedance circuit section 330A' or 330B').

[0031] In the implementation of Fig. 4B, in the impedance circuit section 330A' of the sense coil switching logic section 300A', the first impedance circuit section component Z1 is an inductor L1A and the second impedance circuit section component Z2 is a capacitor C1A. In the implementation of Fig. 4C, in the impedance circuit section 330B' of the sense coil circuit logic section 300B', the first impedance circuit section component Z1 is a capacitor C1B and the second impedance circuit section component Z2 is an inductor L1B. As will be understood by one skilled in the art, in certain implementations, the configuration of Fig. 4B can be characterized as corresponding to a high-pass filter configuration, and the configuration of Fig. 4C can be characterized as corresponding to a low-pass filter configuration. As a specific numerical example, in certain implementations, an operating frequency during operations for the configurations can be 20 MHz.

[0032] It is understood that for applications where low frequency attenuation is desirable (e.g., attenuation of low frequency noise), the configuration of Fig. 4B can be selected / used. Alternatively, for applications where high frequency attenuation is desirable (e.g., attenuation of high frequency noise), the configuration of Fig. 4C can be selected / used. In certain applications, a large part of the noise to be attenuated may typically be in the higher frequencies for which the configuration of Fig. 4C (e.g. as an alternative to certain other possible types of noise reduction components / techniques and with the additional benefit of providing signal amplification, as further described below with respect to Fig. 7B is described in more detail).

[0033] The Fig. 5A and Fig. 5B are diagrams of implementations of the sensing coil circuit section of Fig. 3. It is understood that the above-mentioned provisions in relation to the Fig. 3 and 4A-4C also apply to the implementations of the Fig. 5A and Fig. 5B apply unless otherwise stated below. As described in Fig. 5A, a sense coil circuit logic section 300" includes the first sense coil section 320, an impedance circuit section 330" and the input circuit section 340. The first sense coil section 320 and the input circuit section 340 are the same as those described above with respect to Fig. 4A. A major difference between the configuration of Fig. 5A and the configuration of Fig. 4A is located in the impedance circuit section 330'' compared to the impedance circuit section 330', as described in more detail below.

[0034] In the configuration of Fig. 5A, a sensing circuit section SCP'' is configured to receive a first sensing coil signal from the first sensing coil section 320. The sensing circuit section SCP'' includes the impedance circuit section 330'' and the input circuit section 340. The impedance circuit section 330'' is connected to the first and second coil terminals 321 and 322. The impedance circuit section 330'' includes a first impedance circuit section component Z1 and a second impedance circuit section component Z2. In the impedance circuit section 330'', the first impedance circuit section component Z1 is coupled between a first impedance circuit section node 331 and a second impedance circuit section node 332.The second impedance circuit section component Z2 is also coupled between the first impedance circuit section node 331 and the second impedance circuit section node 332 so as to be coupled in parallel to the first impedance circuit section component Z1.

[0035] As noted above, the input circuit section 340 is the same as that of Fig. 4A (e.g., with similar connections and operations) and is connected to the first and second impedance circuit section nodes 331 and 332. As illustrated, the first and second impedance circuit section components Z1 and Z2 are each coupled in parallel to the input circuit section component ZT, with the components effectively coupled between the first impedance circuit section node 331 and the second impedance circuit section node 332, respectively. The input circuit section 340 is configured to receive an oscillating sense signal (e.g., resulting from the first sense coil signal from the first sense coil section 320 as it passes through the impedance circuit section 330") at the first and second impedance circuit section nodes 331 and 332.A combined impedance section CIP'' includes at least the impedance circuit section 330'' and the first sense coil section 320 and, during operation, has a combined impedance presented to the input circuit section 340.

[0036] Fig. 5B is a more specific implementation of the sense coil circuit logic portion 300'' of Fig. 5A. The first detection coil section 320 and the input circuit section 340 of Fig. 5B are the same as those described above with respect to the Fig. 4B and Fig. 4C. A major difference in the configuration of Fig. 5B compared to the configurations of the Fig. 4B and Fig. 4C is located in the impedance circuit section 330'' compared to the impedance circuit sections 330A' and 330B', as described in more detail below.

[0037] In the implementation of Fig. 5B, in the impedance circuit section 330" of the sense coil circuit logic section 300", the first impedance circuit section component Z1 is a capacitor C2 and the second impedance circuit section component Z2 is a resistor R2. As described in more detail below (e.g., with respect to the Fig. 7A-7D), a desirable selection of resistor R2 (i.e., in parallel with the termination resistor RT of the input circuit section 340, as illustrated) may allow certain other matching elements of the impedance circuit section 330'' to be reduced to the single impedance circuit section component Z1 (e.g., capacitor C2). As described in more detail below, such a configuration may have certain advantages (e.g., where the termination resistor RT may be relatively large, which might otherwise result in a relatively narrow bandwidth, but where the inclusion of resistor R2 may result in some reduction in gain but a wider bandwidth, and where a wider bandwidth may be less sensitive to certain component tolerances and sample times for the signals, etc.).

[0038] The Fig. 6A and Fig. 6B are diagrams of implementations of the sense coil circuit logic portion of Fig. 3. It is understood that the above-mentioned provisions in relation to the Fig. 3, 4A-4C, 5A and 5B also apply to the implementations of the Fig. 6A and Fig. 6B apply unless otherwise stated below. As described in Fig. 6A, a sense coil circuit logic section 300''' includes the first sense coil section 320, an impedance circuit section 330''', and the input circuit section 340. The first sense coil section 320 and the input circuit section 340 are the same as those described above with respect to the Fig. 4A and Fig. 5A. A major difference in the configuration of Fig. 6B compared to the configurations of the Fig. 4A and Fig. 5A is located in the impedance circuit section 330''' compared to the impedance circuit sections 330' and 330'', as described in more detail below.

[0039] In the configuration of Fig. 6A, a sensing circuit section SCP''' is configured to receive a first sensing coil signal from the first sensing coil section 320. The sensing circuit section SCP''' includes the impedance circuit section 330''' and the input circuit section 340. The impedance circuit section 330''' is connected to the first and second coil terminals 321 and 322. The impedance circuit section 330''' includes a first impedance circuit section component Z1, a second impedance circuit section component Z2, and a third impedance circuit section component Z3. In the impedance circuit section 330''', the first impedance circuit section component Z1 is coupled between a first impedance circuit section node 331 and a second impedance circuit section node 332.The second impedance circuit section component Z2 is also coupled between the first impedance circuit section node 331 and the second impedance circuit section node 332 so as to be coupled in parallel with the first impedance circuit section component Z1. The third impedance circuit section component Z3 is coupled between the first coil terminal 321 and the first impedance circuit section node 331.

[0040] As noted above, the input circuit section 340 is the same as that shown in the Fig. 4A and Fig. 5A (e.g., with similar connections and operations) and is connected to the first and second impedance circuit section nodes 331 and 332. As illustrated, the first and second impedance circuit section components Z1 and Z2 are each coupled in parallel to the input circuit section component ZT, with the components effectively coupled between the first impedance circuit section node 331 and the second impedance circuit section node 332, respectively. The input circuit section 340 is configured to receive an oscillating sense signal (e.g., resulting from the first sense coil signal from the first sense coil section 320 as it passes through the impedance circuit section 330''') at the first and second impedance circuit section nodes 331 and 332.A combined impedance section CIP''' includes at least the impedance circuit section 330''' and the first sense coil section 320 and, during operation, has a combined impedance presented to the input circuit section 340.

[0041] Fig. 6B is a more specific implementation of the sense coil circuit logic portion 300''' of Fig. 6A. The first detection coil section 320 and the input circuit section 340 of Fig. 6B are the same as those described above with respect to the Fig. 4B, Fig. 4C and Fig. 5B. A major difference in the configuration of Fig. 6B compared to the configurations of the Fig. 4B, Fig. 4C and Fig. 5B is located in the impedance circuit section 330''' compared to the impedance circuit sections 330A', 330B' and 330'', as described in more detail below.

[0042] In the implementation of Fig. 6B, in the impedance circuit section 330''' of the sense coil circuit logic section 300''', the first impedance circuit section component Z1 is a capacitor C3A, the second impedance circuit section component Z2 is a resistor R3, and the third impedance circuit section component Z3 is a capacitor C3B. As described in more detail below (e.g., with respect to the Fig. 7A-7D), the impedance circuit section 330''' may have certain advantages similar to those of the impedance circuit section 330' of Fig. 4A, and for which the addition of resistor R3 may provide certain additional benefits (e.g., allowing for a wider bandwidth, etc.). In different implementations, the configuration of Fig. 6B may be characterized in that it provides three degrees of freedom for which the values ​​of the components can be selected to produce a desired resonant frequency, peak gain and / or bandwidth (and which has, for example, a corresponding phase slope).

[0043] As mentioned above with regard to the examples of Fig. 4A-4C, 5A-5B and 6A-6B, in different implementations the coil impedance Z Rx of the sense coil section 320 may include the impedance of the inductive section 323 and the resistive section 324 (e.g., the sense coil CL1). The impedance of the input circuit section 340 may include the impedance of the input circuit section component ZT (which may, for example, include a terminating resistor RT) and may, in some implementations, be referred to as the input impedance. In various implementations, the coil impedance Z Rxof the sensing coil section 320 in combination with the impedance of the impedance circuit section 330 is approximately matched to the impedance of the input circuit section 340, or at least approximately matched thereto (e.g., closer to the impedance of the input circuit section 340 than to the coil impedance of the sensing coil section 320 alone), the signal available to the input circuit section 340 can be effectively increased (e.g., in some cases by a relatively significant amount). This results in an improved signal-to-noise ratio (SNR) and / or the ability to increase the field-generating performance (e.g., of a field-generating section, such as including one or more field-generating coils used to induce the current in the sensing coil CL 1 as part of the inductive displacement transducer operations, as discussed above with respect to Fig. 2).

[0044] As described herein, a combined impedance includes a combined reactance and a combined resistance of a sense coil section 320 and an impedance circuit section 330. The components of the impedance circuit section 330 may be configured such that the combined impedance is approximately matched to the impedance of the input circuit section 340, or at least approximately matched (e.g., closer than the sense coil section 320 alone). With respect to the combined reactance, in various implementations, by inserting elements into the impedance circuit section 330 to achieve an approximate match, or at least an approximate match, the combined reactance (e.g., at the operating frequency used during operations), including the reactance of the inductive section 323 of the sense coil section 320, may be effectively reduced or eliminated (and thus, e.g.,approximately matched to, or at least approximately matched to, the reactance of the input circuit portion 340, which may have little or no reactance due to the primary presence of only the termination resistor RT. Furthermore, the combined resistance, which includes the resistance of the resistive portion 324 of the sense coil portion 320, can be effectively transformed to be approximately matched to (e.g., approximately equal to) or at least approximately matched to the resistance of the input circuit portion 340 (e.g., including the resistance of the termination resistor RT). In addition, the source voltage V Sof the sense coil section 320 may appear relatively higher (e.g., due to properties closer to resonance, etc.). Such considerations may maximize or otherwise increase the power transfer from the sense coil section 320 (e.g., including the sense coil CL1) to the input circuit section 340 (e.g., including the termination resistor RT).

[0045] Various techniques can be used to determine the elements (e.g., components) of the impedance circuit section 330 for such purposes. For example, in one implementation, complex number algebra can be used to determine the elements (e.g., with corresponding values) of the impedance circuit section 330 (e.g., to achieve an approximate match or at least an approximate match, as mentioned above). In such an implementation, some general representations for the impedance Z and the admittance Y are given by the following EQUATIONS 1 and 2, respectively: Z=R+jX where j = (-1) 1 / 2 . Y=1 / Z=G+jB

[0046] In general, the elements in the impedance circuit sections (e.g. as in the examples of Fig. 4A-4C, 5A-5B, and 6A-6B) an insertion / inclusion of a series element of an addition of impedances, and an insertion / inclusion of a parallel element of an addition of admittances. In various implementations, two or more elements can be inserted / included in an impedance circuit section.

[0047] The Fig. 7A-7D are diagrams of Smith charts used in some examples for determining the elements of impedance circuit sections such as those of Fig. 4A-4C, 5A-5B, and 6A-6B. In various implementations, such Smith charts can be used as an aid to visualize fitting solutions and can include a polar diagram with reflection coefficients. As shown in Fig. 7A, the impedance and admittance grids are superimposed on the diagrams (for example, impedance is indicated by the correspondingly labeled inner dashed circle and similar inner dashed curves, and admittance is indicated by the correspondingly labeled inner solid circle and similar inner solid curves). In these examples, the diagrams are given as normalized, with all impedances divided by the characteristic impedance Z0, which is purely resistive and set equal to the resistance of the input circuit section component ZT (e.g., equal to the resistance of the termination resistor RT). The normalized characteristic impedance z0 is represented by the small square in the center of each of the diagrams (and may, for example, be characterized in various implementations as representing a relative target for approximate matching, as described above).The following EQUATIONS 3-5 (e.g., in relation to EQUATIONS 1-2 above) give certain relationships related to the characteristic impedance Z0. z0=1+j0 z=Z / Z0=r+jx y=Z0 / Z=g+jb

[0048] In Fig. In Figure 7A, the inner solid admittance circle represents g = 1, where g is the real part of the admittance, and the inner dashed impedance circle represents r = 1. In various implementations, for the examples described herein, the inner solid admittance circle can be considered one of the relatively more important curves in the diagram. The coil impedance z Rxcorresponds to the impedance of the sense coil section 320. As noted above, in various implementations, it may be desirable for the combined impedance of the sense coil section and the impedance circuit section to be closer to (e.g., in some cases, approximately matched to) the characteristic impedance z0, which is purely resistive and set to the resistance of the terminating resistor RT (e.g., corresponding to the small square in the center of the diagram labeled "1", and where, according to EQUATION 3, z0 = 1 + j0). As will be described below using the examples in the Fig. 7B-7D, the elements of the impedance circuit sections can therefore be determined / selected so that the plots are shifted along the respective curves of the Smith charts so that the combined impedance comes closer to (e.g., in some cases, approximately coincides with) the small central square (i.e., the characteristic impedance z0 is equal to the resistance of the terminating resistor RT). It should be noted that the diagrams of the Fig. 7B-7D all of the same illustrated features of the diagram of the Fig. 7A as well as other illustrated features as described in more detail below.

[0049] In relation to Fig. 7B, the illustrated example diagram may, in various implementations, correspond to the example impedance circuit portions of the Fig. 4A-4C, as described in more detail below. In these specific examples, the elements (e.g., components) of the impedance circuit sections include only capacitors and inductors. As a result, impedance and admittance in the diagram vary from Fig. 7B only on circuits with constant r and g. In these examples, no resistors are used (e.g., resistors can lead to losses), but they can be used alternatively in certain other implementations, as with respect to the example of Fig. 7D, which corresponds to the examples of Fig. 5A, Fig. 5B, Fig. 6A and / or 6B, as described in more detail below). In the example of Fig. 7B, the following equations can be used to convert between impedance z and reflection coefficient Γ. In various implementations, these can be used to create a polar diagram (e.g., in mathematical software, etc.). Γ=(z−1) / (z+1) z=(1+Γ) / (1−Γ)

[0050] Below are some specific numerical examples of the values ​​of certain elements, such as the impedance Z Rx of the detection coil section 320 and the resistance of the terminating resistor RT at an operating frequency of 20 MHz. ZRx=(0.97+j7.21)Ω at 20 MHz where 0.97 ohms is the impedance (e.g., including resistance) of resistive section 324, and j7.21 ohms is the impedance (e.g., including reactance) of inductive section 323. In general, the impedance of an inductor and / or inductive section is Z = j*ω*L, where ω = 2*π*frequency. In this example (e.g., where the operating frequency is 20 MHz and the inductance of inductive section 323 is L = 57.4 nH), this calculation can be represented as Z = j*2*π*20,000,000*57.4*10^(-9) = j7.21 Ω.

[0051] The resistance of the terminating resistor RT is 500 Ω (i.e., 500 ohms). Thus, according to the above techniques, Z0 = 500 Ω, and the normalization is performed as follows: zRx=ZRx / Z0=0.00194+j0.0144 yRx=1 / zRx=9.16−j68.12

[0052] Since in the example of Fig. 7B g = 9.16 corresponds to a circle within g = 1 (e.g. in Fig. 7B as a smaller dashed circle inside the circle corresponding to g = 1), this indicates in various implementations that achieving r = 1 cannot generally be achieved by adding a parallel element. This means that the first element with the sense coil CL1 with coil impedance Z Rx must be connected in series (e.g. where the first element of an impedance circuit section component Z2 in the example of Fig. 4A). In various implementations, the combined impedance (e.g., including the impedance z Rx ) along the circle r = 0.00194 until an intersection point g = 1 is reached. The circle r = 0.00194 is in Fig. 7B as a relatively large dashed circle (i.e., it is almost as large as the diagram) and its value is given in EQUATION 8. In the representation of Fig. 7B, the circle r = 0.00194 intersects the circle g = 1 at two points, indicating that there are two solutions.

[0053] As a first solution (e.g. “solution a”), as in the example of Fig. 4B, a series capacitor C1A is inserted / included, which in the example of Fig. 7B shifts the combined impedance towards the capacitive side of the diagram so that g = 1 (i.e. as indicated by the curved downward-pointing arrow labelled “cap” extending from z Rx downwards and follows the circle r = 0.00194 to intersect the circle g = 1). In addition, a parallel inductor L1A is inserted / included (e.g., parallel to the input circuit section component ZT), which in the example of Fig. 7B shifts the combined admittance counterclockwise along the circle g = 1 so that r = 1 (i.e., as indicated by the curved, rightward and upward-pointing arrow labeled “ind” extending from the end of the “kap” arrow and following the circle g = 1 counterclockwise to intersect the circle r = 1 approximately at the small central square “1”). As noted above, the small central square corresponds to the normalized characteristic impedance z0, which corresponds to the termination resistance RT for which the configuration of Fig. 4B (e.g. with the properties as in Fig. 7B) thus at least approximately achieves a desired match, such as for the reactance, which may be relatively minimal (e.g., with the combined reactance relatively reduced and / or eliminated), as described above.

[0054] As a second solution (e.g. “solution b”), as in the example of Fig. 4C, a series inductor L1B is inserted / included, which in the example of Fig. 7B shifts the combined impedance towards the inductive side of the diagram so that g = 1 (i.e. as indicated by the curved, upward-pointing dashed arrow labelled ‘ind’ extending from z Rx upwards and follows the circle r = 0.00194 to intersect the circle g = 1). In addition, a parallel capacitor C1B is inserted / included, which in the example of Fig. 7B shifts the combined admittance clockwise along g = 1 so that r = 1 (i.e., as indicated by the curved, rightward and downward pointing dashed arrow labeled “kap” extending from the end of the “ind” arrow and following the circle g = 1 clockwise to intersect the circle r = 1 approximately at the small central square “1”). As noted above, the small central square “1” corresponds to the normalized characteristic impedance z0, which corresponds to the termination resistance RT for which the configuration of Fig. 4C (e.g. with the properties as in Fig. 7B) thus at least approximately achieves a desired match, such as for the reactance, which may be relatively minimal (e.g., with the combined reactance relatively reduced and / or eliminated), as described above.

[0055] With regard to the above concepts, various calculations described below illustrate the determination of values ​​for certain components. As a first calculation, a series reactance x1 can be calculated such that the resulting admittance g = 1. The following equation assumes capacitive reactance: 1 / (zRx−jx1)=1+jb

[0056] Using well-known algebraic techniques, two solutions can be found as given below: x1=xRx±(r−r2)1 / 2=0.0584 or−0.0296

[0057] The positive result represents the reactance of the capacitor C1A (ie of Fig. 4B), while the negative result represents the reactance of the inductor L1B (ie of Fig. 4C), with example values ​​as given below. C1A=1 / (0.0584⋅ωZ0)=272 pF L1B=−(−0.0296)Z0 / ω=118 nH

[0058] The admittance after inserting x1 is given below. y1=1 / (ZRx−jx1)=1±j22.68

[0059] Parallel elements with susceptance b = ±22.68 are given below, where the parallel elements in these examples are the inductor L1A (ie of Fig. 4B) and the capacitor C1B (ie from Fig. 4C), with example values ​​as given below. L1A=Z0 / (22.68ω)=175 nH C1B=22.68 / (ωZ0)=361 pF

[0060] With example values ​​like the ones above, an example voltage gain can be given to both the configuration of Fig. 4B as well as the configuration of Fig. 4C is approximately 11.35 (21.1 dB) (which can be compared, for example, to a gain of 1.0 of a "mismatched" circuit without the impedance circuit section 330). Thus, a relatively significant increase in gain can be achieved by using the configurations disclosed herein. In various implementations, a frequency response for each configuration can be calculated based on a voltage divider formula, as provided below. VL=VS(Zb(ω)) / (Zb(ω)+Za(ω))

[0061] In EQUATION 17, the voltages V L and V S as in the Fig. 4B and Fig. 4C, and Z b (ω) can be a combination of the circuit elements L1A and RT of Fig. 4B or C1B and RT from Fig. 4C, and Z a (ω) can be a combination of the circuit elements CL1 and C1A of Fig. 4B or CL1 and L1B of Fig. 4C. In the configuration of Fig. 4B shows that low frequencies can be attenuated, and as some example values, the 3 dB bandwidth can be 242 kHz and the phase slope can be -0.756 degrees / 10 kHz. In the configuration of Fig. 4C shows that high frequencies can be attenuated (which can be advantageous, for example, to suppress certain electromagnetic interference from external sources, etc.), the 3 dB bandwidth can be 336 kHz, and the phase slope can be -0.543 degrees / 10 kHz. Therefore, it is obvious that the configuration of Fig. 4B or Fig. 4C (or similar configurations) can be selected for specific applications depending on the required properties (e.g. using the configuration of Fig. 4B or Fig. 4C for damping low or high frequencies).

[0062] Fig. Figure 7C shows a diagram similar to that of Fig. 7B, with certain differences as indicated below. The main difference is shown in the example of Fig. 7C the coil impedance Z Rx is indicated as lying outside the circle g = 1. In different implementations, this can indicate four possible solutions, since both g = 1 and r = 1 are achievable. Two of the solutions allow the use of only capacitors in the impedance circuit section, and the other two solutions include inductors. The two possible solutions that include only capacitors are described in more detail below.

[0063] In relation to Fig. 4A are in the two solutions that use only capacitors in the impedance circuit section 330' of Fig. 4A, components Z1 and Z2 are both capacitors. As a first solution, a series capacitor is inserted / included (e.g. as component Z2 in Fig. 4A), which in the example of Fig. 7C shifts the combined impedance downwards so that g = 1 (i.e. as indicated by the curved downward-pointing arrow labeled “kap” extending from z Rx downwards and follows the circle r = 0.00194 to intersect the circle g = 1). In addition, a parallel capacitor is inserted / included (e.g. as component Z1 in Fig. 4A and as parallel to the input circuit section component ZT), which in the example of Fig. 7C shifts the combined admittance clockwise along the circle g = 1 so that r = 1 (i.e., as indicated by the curved, rightward and downward-pointing arrow labeled “kap” extending from the end of the first “kap” arrow and following the circle g = 1 clockwise to intersect the circle r = 1 approximately at the small central square “1”). As discussed above with respect to Fig. 7B, with such properties, at least approximately a desired match is achieved, such as for the reactance, which may be relatively minimal (e.g., with the combined reactance relatively reduced and / or eliminated), as described above.

[0064] As a second solution, a parallel capacitor is inserted / included (e.g. as a second impedance circuit section component Z2), which in the example of Fig. 7C shifts the combined impedance to the right to reach the circle r = 1 (i.e. as indicated by the curved dashed arrow labeled “kap” extending from z Rx extends to intersect the circle r = 1). In addition, a series capacitor is inserted / included (e.g., as a first impedance circuit section component Z1, with component Z2 in parallel and component Z1 in series on the right side of component Z2, compared to the example of Fig. 4A, in which component Z2 is in series and component Z1 is in parallel with component ZT, but otherwise with similar connections of the impedance circuit sections, such as including component ZT as coupled / connected between the first and second impedance circuit section nodes 331 and 332, etc.). This configuration of the second solution (i.e., in the example of Fig. 7C) shifts the combined admittance counterclockwise along r = 1 to reach the central square '1' (i.e., as indicated by the curved, downward-pointing dashed arrow labeled 'kap' extending from the end of the other 'kap' arrow and following counterclockwise the circle r = 1 to the small central square '1').

[0065] In relation to Fig. 7D, the illustrated example diagram may, in various implementations, correspond to the example impedance circuit portions of the Fig. 5A and Fig. 5B, as described in more detail below. As mentioned above, there is a difference to the configurations of the Fig. 4B and Fig. 4C is that in the configuration of Fig. 5B, the impedance circuit section 330" includes a resistor R2 (e.g., as a second impedance circuit section component Z2). In some implementations, the resistor R2 may be characterized by substantially modifying the effective input impedance of the input circuit section 340 (e.g., by resistors R2 and RT in parallel providing a combined resistance that is lower than that of resistor RT alone). In some implementations, as shown in the diagram of Fig. 7D, this can be viewed as a reduction in the effective characteristic impedance Z0, which is purely resistive and set equal to the effective input resistance (which, in this example, may include, for example, the combined resistance of resistor R2 and the parallel-connected termination resistor RT). As mentioned above, the graph is normalized, meaning all impedances have been divided by the characteristic impedance Z0. As above, the normalized characteristic impedance z0 is represented by the small square "1" in the center of the graph.

[0066] With further reference to the diagram of Fig. 7D is set in this equation for the admittance g = 1. Y=Z0 / ZRx=1+jb

[0067] This has the solution: Z0=R+(ωL)2 / R b=−ωL / R where for the parallel resistor R2 of the configuration of Fig. 5B applies: R2=1 / (1 / Z0−1 / RT)

[0068] Finally, the parallel capacitor C2 is inserted for at least an approximate adjustment: C2=−b / (ωZ0)

[0069] As some specific example values, in one configuration, the resistance of R2 may be 61.25 ohms and the capacitance of capacitor C2 may be 1.084 nF (for example, the values ​​of the components may be calculated using techniques similar to those described above). The values ​​of the other components may be similar to those in the above examples (e.g., the inductive section 323 has an inductance of 57.4 nH, the resistive section 323 has a resistance of 0.97 ohms, the termination resistor RT has a resistance of 500 ohms, etc.). In various implementations, the inclusion of a parallel resistor (e.g., resistor R2) may be particularly useful when the resistance of the termination resistor RT may be relatively high (e.g., equal to 4 kOhms).In various implementations, if the resistance of the termination resistor RT is significantly larger than the resistance of the resistive section 324, the reactance of the matching component can become very large and relatively tolerance-sensitive. In certain implementations (e.g., as shown in . Fig. 6B), the parallel resistor R2 can be configured as Fig. 4A (e.g. when two capacitors are used as components Z1 and Z2, as in the diagram of Fig. 7C) and aim at a desired gain, as described in more detail below.

[0070] With the example values ​​for the components mentioned above (e.g., and with the combined resistance of resistor R2 in parallel with the termination resistor RT), the effective characteristic impedance Z0 is reduced to 54.6 ohms. In this example, this is a relatively large reduction compared to the original 500 ohm value of the termination resistor RT alone, but the voltage gain is still 3.75 (11.5 dB). By reducing the effective characteristic impedance Z0, the thermal noise in the termination resistor RT is also reduced. As further example values ​​related to the configuration of Fig. 5B, the 3 dB bandwidth can be 872 kHz and the phase slope can be -0.213 degrees / 10 kHz.

[0071] In an alternative implementation, where the goal is resonance rather than approximate matching, a configuration similar to that in Fig. 4C (e.g., except without the series inductor L1B), in which the parallel capacitor C1B is used to adjust the resonance peak voltage to the target frequency. It should be noted that adjustment techniques such as those described above can lead to configurations with relatively higher voltage gains than those configurations that are more aligned with resonance. For example, the configuration of Fig. 4C, as described above, may have a voltage gain of about 11.35 (21.1 dB) in a particular implementation, while a similar resonant version, as described in more detail below (e.g., without the inductor L1B and with a different value for the parallel capacitor C1B), may have a voltage gain of about 6.75 (16.5 dB), with the voltage gain of the resonant version being only about 60 percent of the voltage gain of the matching version.

[0072] As mentioned above, in a resonance version of a configuration similar to that of Fig. 4C (e.g., including the parallel capacitor C1B, but without the series inductor L1B), the parallel capacitor C1B can be used to adjust the resonant peak voltage to the target frequency. For such a version, a simplified technique for calculating an approximate value of the parallel capacitor C1B can use a classical equation for the resonance of an LC tank circuit (where, for the sake of simplicity, the effects of the resistive section 324 and the termination resistor RT on the resonant peak are ignored in the following simplified equations, which follow the general form ω = 1 / (LC) 1 / 2 for an inductance L and capacitance C of an LC resonant circuit). ω=1 / ((L323)(C1B))1 / 2 where L 323is the inductance of the inductive section 323 and this is in accordance with the other example values ​​as given above, where ω = 2*π*frequency, where the operating frequency is 20 MHz and the inductance of the inductive section 323 is L = 57.4 nH, then: C1B=1 / ((ω2)(L323))=1.104 nF

[0073] By performing a more detailed calculation of the value of C1B to achieve resonance (e.g., taking into account the effects of the resistive section 324 and the termination resistor RT, and setting the voltage derivative with respect to frequency to zero, using relatively complex algebra, as will be apparent to one skilled in the art), a more accurate value than C1B = 1.094 nF can be determined in this example (which can, for example, place the resonance peak precisely at the target frequency). Using this value for such an exemplary resonant version can result in a voltage gain of approximately 6.75 (16.5 dB) at the operating frequency of 20 MHz. A version using the value C1B = 1.104 nF from EQUATION 24 (which is relatively close to the more accurate value) can result in a somewhat lower voltage gain and a voltage peak that deviates slightly from the target frequency.In any case, as noted above, in these particular examples, the voltage gains of such resonant versions may be relatively lower (e.g., 60 percent or less) than the voltage gain of the version formed using matching principles as discussed above with respect to . Fig. 4C (ie with the voltage gain of about 11.35 (21.1 dB)).

[0074] With regard to configurations that use adaptation principles such as those described above, Fig. 6B, which illustrates another configuration with certain desirable properties. In certain implementations, the configuration of Fig. 6B as a combination of a configuration of Fig. 4A (ie with capacitors as components Z1 and Z2) with a parallel resistor R3 (e.g. similar to the parallel resistor R2 of Fig. 5B). It will be clear that a configuration such as that of Fig. 6B can exhibit properties such as a wider bandwidth and a reduced phase slope (e.g. compared to the other example configurations described above).

[0075] Regarding the configuration of Fig. 6B applies, expressed as some specific numerical examples: If the resistor R3 has a value of 51 ohms and the combined resistance of resistor R3 is in parallel with the terminating resistor RT, the effective characteristic impedance Z0 is reduced to 46.3 ohms. Such a configuration can be used, similar to the ones described above with regard to the diagram in Fig. 7C described examples, lead to Rx outside the circle g = 1. Accordingly, the components Z1 and Z3 of Fig. 6A can be implemented as capacitors (e.g. as described above with reference to the diagram of Fig. 7C and as described in Fig. 6B for the respective capacitors C3A and C3B).

[0076] As some specific example values, in one configuration the capacitance of capacitor C3A may be 1.175 nF and the capacitance of capacitor C3B may be 13.7 nF (for example, the values ​​of the components may be calculated using techniques similar to those described above with respect to Fig. 7C, etc.). The values ​​of the other components may be similar to those in the above examples (e.g., the inductive section 323 has an inductance of 57.4 nH, the resistive section 323 has a resistance of 0.97 ohms, the terminating resistor RT has a resistance of 500 ohms, the resistor R3 has a resistance of 51 ohms, etc.). With such example values, an example voltage gain of the configuration of Fig. 6B can be approximately 3.45 (10.8 dB), the 3 dB bandwidth can be 2.04 MHz, and the phase slope can be -0.089 degrees / 10 kHz. It should be noted that the configuration of Fig. 6B in various implementations can effectively extend the bandwidth and reduce the phase slope (e.g., compared to the other example configurations described above). For example, as noted above with respect to certain possible example component values, the configuration of Fig. 4B characteristics for which the 3 dB bandwidth can be 242 kHz and the phase slope can be -0.756 degrees / 10 kHz, the configuration of Fig. 4C can have characteristics for which the 3 dB bandwidth can be 336 kHz and the phase slope can be -0.543 degrees / 10 kHz, and the configuration of Fig. 5B may have characteristics for which the 3 dB bandwidth may be 872 kHz and the phase slope may be -0.213 degrees / 10 kHz (noting, for example, that they all have narrower bandwidths and steeper phase slopes than the example configuration of Fig. 6B).

[0077] Below are some features of the example configurations described above. Fig. 4A-4C and 6A-6B (e.g., different features may be desirable depending on the specific application). The example configurations of the Fig. 4A-4C have the highest gains of the examples (e.g., they represent an upper limit on achievable gain in some implementations), and these configurations generally also have the narrowest bandwidth and steepest phase slopes. The example configurations of Fig. 6A-6B generally illustrate that component values ​​can be selected to generally target a particular desired gain, bandwidth, or slope (e.g., with a maximum gain as in the examples of Fig. 4A-4C, as mentioned above). In different implementations, a relatively large range (e.g., like that of the example configuration of Fig. 6B) help to minimize problems resulting from slight shifts in the resonance peak (e.g., due to component tolerances and / or slight changes / differences in the characteristics of the sense coil CL1, including the inductive section 323 and / or the resistive section 324, such as may occur due to the gap variation and / or position on the scale of the overall inductive displacement transducer, as discussed above with respect to Fig. 2, etc., may occur).

[0078] In particular, it should be noted that the example configuration of Fig. 6B comprises an impedance circuit section 330''' including three relatively inexpensive components (e.g., capacitors C3A and C3B and resistor R3), wherein the configuration can be repeated for the different phases of the entire inductive displacement transducer (e.g., as described above with respect to Fig. 2). In certain implementations, the use of only capacitors and resistors (e.g. as in Fig. 6B) compared to configurations with inductors (e.g. as shown in the Fig. 4A and Fig. 4B) may be preferable, perhaps because the component tolerances of capacitors and resistors in some implementations are generally better / more consistent than those of inductors, etc. In various implementations, it may be desirable to use relatively low temperature coefficient (TC) components (e.g., NPO ceramic capacitors, etc.). It should be noted that, in general, the maximum possible gain may increase as ωL / R increases and / or as RT / R 324 increases (e.g. where R 324 the resistance of the ohmic section 324).

[0079] As mentioned above, the operating frequency in various implementations for each of the configurations described herein may be 20 MHz as a specific numerical example. With respect to matching techniques such as those described above, it may generally be desirable to use such a relatively high operating frequency (for example, the matching techniques may be relatively more effective at achieving the desired benefits at relatively high operating frequencies). It should also be noted that configurations that use a relatively large or high-value termination resistor RT may provide relatively great flexibility for the matching techniques.

[0080] Fig. 8 is a flowchart illustrating an exemplary routine 800 for operating an inductive displacement transducer system (e.g., including an impedance circuit portion such as that described herein). At a block 810, a drive signal having an operating frequency is provided to a first field-generating coil portion to generate a changing magnetic flux surrounding at least a portion of a first sensing coil portion, the first sensing coil portion having a first coil terminal, a second coil terminal, and a coil impedance. At a block 820, a first sensing coil signal is received from the first sensing coil portion at a sensing circuit portion, indicating a relative position between the first sensing coil portion and a scale element.In various implementations, the first sense coil signal results from the changing magnetic flux inducing current in the first sense coil portion, as modified by signal modulation elements of the scale element to varying degrees depending on the relative position along the scale element, and wherein the first sense coil signal accordingly indicates a relative position between the first sense coil portion and the scale element.

[0081] The sensing circuit portion includes an impedance circuit portion connected to the first and second coil terminals, and an input circuit portion. The impedance circuit portion includes a first impedance circuit portion component and a second impedance circuit portion component. The first impedance circuit portion component is coupled between a first impedance circuit portion node and a second impedance circuit portion node. The second impedance circuit portion is at least one of: coupled between the first impedance circuit portion node and the second impedance circuit portion node; or coupled between the first coil terminal and the first impedance circuit portion node. The input circuit portion is connected to the first and second impedance circuit portion nodes, wherein the input circuit portion has an input impedance during operation.The input circuit section is configured to receive an oscillating sense signal at the first and second impedance circuit section nodes (e.g., as a result of the sense coil signal received at the sense circuit section). A combined impedance section, including at least the impedance circuit section and the first sense coil section, has a combined impedance presented to the input circuit section during operation.

[0082] In various implementations, the method may further include determining a relative position between the first sense coil portion and the scale element (e.g., corresponding to a relative position between a read head and the scale element) based at least in part on the received oscillating sense signal at the first and second impedance circuit portion nodes. In various implementations, determining the relative position between the first sense coil portion and the scale element may correspond to / be achieved by determining a relative position between a read head and the scale element. As described above, a read head may include a plurality of sense coil portions and impedance circuit portions (e.g., sense coil portions 120-n and impedance circuit portions 130-n of Fig. 2) which require a determination of a relative position between the reading head and the scale element (e.g. scale 110 of Fig. 2) may be based at least in part on processing and / or otherwise combining a plurality of oscillating sense signals received at a plurality of respective first and second impedance circuit section nodes.

[0083] In the following, certain exemplary embodiments of the present disclosure are described with various features and elements that are provided with reference numerals that are shown in Fig. 1-8. It is understood that the reference numerals are added to indicate exemplary embodiments, and the features and elements are not limited to the specific embodiments shown in Fig. 1-8 are illustrated.

[0084] An inductive displacement transducer system 100 is provided, including an inductive displacement transducer 108 and a sensing circuit portion SCP. In various implementations, a sensing circuit portion SCP is provided for each sensing coil portion 120-n (e.g., for each sensing coil) of the inductive displacement transducer 108.

[0085] The inductive displacement transducer 108 includes at least a first sensing coil section 320 / 120A1 (e.g., with a first sensing coil) with a first coil terminal 321, a second coil terminal 322, and a coil impedance. The sensing circuit section SCP is configured to receive a first sensing coil signal from the first sensing coil section 320. The sensing circuit section SCP includes an impedance circuit section 330 / 130-A1 and an input circuit section 340 (e.g., an application-specific integrated circuit (ASIC)).

[0086] The impedance circuit section 330 is connected to the first and second coil terminals 321 and 322. The impedance circuit section 330 includes a first impedance circuit section component Z1 and a second impedance circuit section component Z2. The first impedance circuit section component Z1 is coupled between a first impedance circuit section node 331 and a second impedance circuit section node 332. The second impedance circuit section component Z2 is at least one of: coupled between the first impedance circuit section node 331 and the second impedance circuit section node 332; or coupled between the first coil terminal 321 and the first impedance circuit section node 331.

[0087] The input circuit section 340 (e.g., of the ASIC) is connected to the first and second impedance circuit section nodes 331 and 332. The input circuit section 340 has an input impedance during operation (e.g., while using an operating frequency), and the input circuit section 340 is configured to receive an oscillating sense signal at the first and second impedance circuit section nodes 331 and 332. A combined impedance section CIP, comprising at least the impedance circuit section 330 and the first sense coil section 320, has a combined impedance during operation, which is presented to the input circuit section 340 (e.g., of the ASIC).

[0088] In various implementations, the sense coil section 320 comprises a sense coil CL1 comprising the first coil terminal 321, the second coil terminal 322, and the coil impedance. The sense coil CL1 comprises an inductive section 323 and a resistive section 324. The input impedance of the input circuit section 340 comprises the impedance of an input circuit section component ZT coupled between the first impedance circuit section node 331 and the second impedance circuit section node 332. In various implementations, the input circuit section component ZT comprises a resistor RT. In various implementations (e.g., as shown in the Fig. 6A and Fig. 6B), the impedance circuit portion 330''' may further comprise a third impedance circuit portion component Z3 coupled between the first coil terminal 321 and the first impedance circuit portion node 331. In various implementations, the third impedance circuit portion component Z3 comprises a capacitor C3B.

[0089] In various implementations, the sense coil section 320 includes an inductive section 323 that, during operation, has an associated reactance that would otherwise be presented to the input circuit section 340, but in which a majority of the reactance is incorporated in the combined impedance as a result of the inclusion of the impedance circuit section 330 (e.g., the configurations of the Fig.4A-4C, 5A-5B, and 6A-6B) is eliminated in the combined impedance section CIP. In various implementations, one or more impedance circuit section components of the impedance circuit section are configured to eliminate most of the reactance of the inductive section of the sense coil section.

[0090] It should be understood that the principles disclosed and claimed herein may be readily and desirably combined with various features disclosed in the incorporated references. The various implementations described above may be combined to provide further implementations. All U.S. patents and U.S. patent applications cited in this specification are hereby incorporated by reference in their entirety. Aspects of the implementations may be modified, if desired, to incorporate concepts of the various patents and applications to provide still further implementations. These and other changes may be made to the implementations in light of the foregoing detailed description.In general, in the following claims, the terms used should not be construed to limit the claims to the specific implementations disclosed in the specification and claims, but should be construed to include all possible implementations, together with the full scope of equivalents to which such claims are entitled. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 6,005,387

[0002] US 6,011,389

[0002] US 5,901,458

[0003] US 5,886,519

[0003] US 6,859,762

[0012] US 6.304.832 [0014, 0021]

Claims

[1] Inductive position transducer system, comprising: an inductive position transducer that provides a first Sensing coil section having a first coil terminal, a second coil terminal and a coil impedance; and a detection circuit section configured to receive a first detection coil signal from the first detection coil section, the detection circuit section comprising: an impedance circuit portion connected to the first and second coil terminals, the impedance circuit portion comprising: a first impedance circuit section component, the first impedance circuit section component being coupled between a first impedance circuit section node and a second impedance circuit section node; and a second impedance circuit section component which is at least one of: coupled between the first impedance circuit section node and the second impedance circuit section node; or coupled between the first coil terminal and the first impedance circuit section node; and an input circuit section connected to the first and second impedance circuit section nodes, the input circuit section having an input impedance during operation, the input circuit section being configured to receive an oscillating detection signal at the first and second impedance circuit section nodes; wherein a combined impedance section comprising at least the impedance circuit section and the first sense coil section has a combined impedance presented to the input circuit section during operation. [2] The system of claim 1, wherein the sensing coil portion comprises a sensing coil including the first coil terminal, the second coil terminal, and the coil impedance. [3] The system of claim 2, wherein the sensing coil comprises an inductive portion and a resistive portion. [4] The system of claim 1, wherein the input impedance of the input circuit section comprises the impedance of an input circuit section component coupled between the first impedance circuit section node and the second impedance circuit section node. [5] The system of claim 4, wherein the input circuit portion component comprises a resistor. [6] The system of claim 1, wherein the second impedance circuit section component is coupled between the first impedance circuit section node and the second impedance circuit section node. [7] The system of claim 6, wherein the impedance circuit section further comprises a third impedance circuit section component coupled between the first coil terminal and the first impedance circuit section node. [8] The system of claim 7, wherein the third impedance circuit section component comprises a capacitor. [9] The system of claim 1, wherein the first impedance circuit section component comprises one of a capacitor or an inductor. [10] The system of claim 9, wherein the first impedance circuit section component comprises a capacitor. [11] The system of claim 9, wherein the second impedance circuit section component comprises one of a capacitor, an inductor, or a resistor. [12] The system of claim 11, wherein the second impedance circuit section component comprises a resistor. [13] The system of claim 12, wherein the first impedance circuit section component comprises a capacitor and the second impedance circuit section component is coupled between the first impedance circuit section node and the second impedance circuit section node. [14] The system of claim 1, wherein the sense coil portion comprises an inductive portion having, during operation, an associated reactance that would otherwise be presented to the input circuit portion, but wherein a majority of the reactance is eliminated in the combined impedance as a result of the inclusion of the impedance circuit portion in the combined impedance portion. [15] The system of claim 14, wherein one or more impedance circuit section components of the impedance circuit section are configured to eliminate most of the reactance of the inductive section of the sense coil section. [16] A method for operating an inductive displacement transducer system comprising at least one scale element, a first field-generating coil section, and at least one first sensing coil section having a first coil terminal, a second coil terminal, and a coil impedance, the method comprising: Providing a drive signal having an operating frequency for the first field-generating coil section for generating a changing magnetic flux surrounding at least a portion of the first sensing coil section; and Receiving, at a detection circuit section, a first detection coil signal from the first detection coil section indicating a relative position between the first detection coil section and the scale element, the detection coil section comprising: an impedance circuit portion connected to the first and second coil terminals, the impedance circuit portion comprising: a first impedance circuit section component, the first impedance circuit section component being coupled between a first impedance circuit section node and a second impedance circuit section node; and a second impedance circuit section component which is at least one of: coupled between the first impedance circuit section node and the second impedance circuit section node; or coupled between the first coil terminal and the first impedance circuit section node; and an input circuit section connected to the nodes of the first and second impedance circuit sections, the input circuit section having an input impedance during operation, the input circuit section receiving an oscillating detection signal at the first and second impedance circuit section nodes; wherein a combined impedance section comprising at least the impedance circuit section and the first sense coil section has a combined impedance presented to the input circuit section during operation. [17] The method of claim 16, further comprising determining a relative position between the first sense coil portion and the scale element based at least in part on the received oscillating signal at the first and second impedance circuit portion nodes. [18] A sensing circuit section for inclusion in an inductive displacement transducer system, comprising a first sensing coil section having a first coil terminal, a second coil terminal and a coil impedance, the sensing circuit section comprising: an impedance circuit portion connected to the first and second coil terminals, the impedance circuit portion comprising: a first impedance circuit section component, the first impedance circuit section component being coupled between a first impedance circuit section node and a second impedance circuit section node; and a second impedance circuit section component which is at least one of: coupled between the first impedance circuit section node and the second impedance circuit section node; or coupled between the first coil terminal and the first impedance circuit section node; and an input circuit section connected to the first and second impedance circuit section nodes, the input circuit section having an input impedance during operation, the input circuit section being configured to receive an oscillating detection signal at the first and second impedance circuit section nodes; wherein a combined impedance section comprising at least the impedance circuit section and the first sense coil section has a combined impedance presented to the input circuit section during operation. [19] The sensing circuit section of claim 18, wherein the second impedance circuit section component is coupled between the first impedance circuit section node and the second impedance circuit section node. [20] The sensing circuit section of claim 19, wherein the impedance circuit section further comprises a third impedance circuit section component coupled between the first coil terminal and the first impedance circuit section node.

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