Inductive position transducer system with impedance circuit part

Abstract

To provide an inductive position transducer.SOLUTION: An impedance circuit part comprises at least first and second impedance circuit parts 130-A1, 130-A1. The first impedance circuit part 130-A1 is coupled between first and second impedance circuit part nodes. The second impedance circuit part 130-A1 is coupled between a first coil terminal and the first impedance circuit part node or coupled between the first impedance circuit part node and the second impedance circuit part node.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to metrology, and more particularly, to inductive position transducer systems. [Background technology]

[0002] Inductive position transducer systems may be utilized to measure relative displacement between one or more sensing coils (e.g., which may alternatively be referred to as receiving coils or windings) and one or more signal modulating elements (e.g., scale elements) that modulate the inductive coupling between the sensing coils and a magnetic field generating coil (e.g., which may alternatively be referred to as a transmitting coil). Various conventional inductive position transducer systems (such as those disclosed in U.S. Pat. Nos. 6,005,387 and 6,011,389, each of which is incorporated herein by reference in its entirety) use a relatively low power intermittent drive circuit to provide a time-varying drive signal at an operating frequency to the magnetic field generating coil.

[0003] An example of an inductive position transducer system using highly accurate measurement techniques is shown in U.S. Patent No. 5,901,458, which is incorporated herein by reference in its entirety. As described in the '458 patent, the inductive position transducer system has a reduced offset position 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 shown in U.S. Patent No. 5,886,519, which is incorporated herein by reference in its entirety. The '519 patent discloses an absolute inductive position transducer system for high-precision applications such as linear or rotary encoders, electronic calipers, etc. The inductive position transducer system uses two members that are movable relative to each other. The first member includes at least one active magnetic 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. A passive second member (e.g., a scale member) includes passive signal modulating elements that modulate the received magnetic field in response to their position relative to the at least one sensing coil. Electronic circuitry coupled to the at least one magnetic field generating coil and the at least one sensing coil compares the output of the at least one sensing coil to assess the absolute position between the two members and provides the determined absolute position on a display.

[0004] While such inductive position transducer systems can be utilized to determine the position between two members, in some applications it may be desirable to improve the level and / or processing of the signal from the sensing coil, and an inductive position transducer system having improved characteristics is desirable. Summary of the Invention

[0005] This Summary is provided to introduce a selection of concepts in a simplified form 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 used as an aid in determining the scope of the claimed subject matter.

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

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

[0008] Input circuitry (e.g., of an ASIC) is connected to a first impedance circuitry node and a second impedance circuitry node. The input circuitry has an input impedance during operation (e.g., while an operating frequency is utilized), and the input circuitry is configured to receive an oscillating sense signal at the first impedance circuitry node and the second impedance circuitry node. A composite impedance portion comprising at least the impedance circuitry and the first sense coil section has a composite impedance that is presented to the input circuitry (e.g., of an ASIC) during operation. In various implementations, the components of the impedance circuitry can be selected / configured such that the composite impedance approximately matches, or at least approximately matches, the input impedance of the input circuitry (e.g., compared to the impedance of the sense coil section itself, which typically does not match the input impedance of the input circuitry well).

[0009] According to another aspect, a method is provided for operating an inductive position transducer system comprising at least a scale member, a first magnetic field generating coil section, and at least a first sensing coil section (e.g., having a first sensing coil) having a first coil terminal, a second coil terminal, and a coil impedance. The method includes providing a drive signal at an operating frequency to the first magnetic field generating coil section to generate a varying magnetic flux surrounding at least a portion of the first sensing coil section, and receiving at a sensing circuitry a first sensing coil signal from the first sensing coil section indicative of a relative position between the first sensing coil section and the scale member. The sensing circuitry comprises an impedance circuitry and an input circuitry. In various implementations, the method can further include determining a relative position between the first sensing coil section and the scale member (e.g., as corresponding to a relative position between a readhead and the scale member) based at least in part on the oscillating sense signal received at the first impedance circuitry node and the second impedance circuitry node.

[0010] According to another aspect, sensing circuitry is provided for inclusion in an inductive position transducer system, the sensing circuitry comprising impedance circuitry and input circuitry. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram of an inductive position transducer system. [Diagram 2] 2 is a block diagram of a more specific implementation of the inductive position transducer system of FIG. 1. [Diagram 3] FIG. 3 is a diagram of a sensing coil circuit portion of an inductive position transducer system such as those of FIGS. 1 and 2. [Figure 4A] FIG. 4 is a diagram of an implementation of the sense coil circuitry of FIG. 3 including a first impedance circuitry component coupled between a first impedance circuitry node and a second impedance circuitry node, and including a second impedance circuitry component coupled between a first coil terminal and the first impedance circuitry node. [Figure 4B] FIG. 4 is a diagram of an implementation of the sense coil circuitry of FIG. 3 including a first impedance circuitry component coupled between a first impedance circuitry node and a second impedance circuitry node, and including a second impedance circuitry component coupled between a first coil terminal and the first impedance circuitry node. [Figure 4C] FIG. 4 is a diagram of an implementation of the sense coil circuitry of FIG. 3 including a first impedance circuitry component coupled between a first impedance circuitry node and a second impedance circuitry node, and including a second impedance circuitry component coupled between a first coil terminal and the first impedance circuitry node. [Figure 5A]FIG. 4 is a diagram of an implementation of the sense coil circuitry of FIG. 3 including a first impedance circuitry component coupled between a first impedance circuitry node and a second impedance circuitry node, and including a second impedance circuitry component coupled in parallel with the first impedance circuitry component. [Figure 5B] FIG. 4 is a diagram of an implementation of the sense coil circuitry of FIG. 3 including a first impedance circuitry component coupled between a first impedance circuitry node and a second impedance circuitry node, and including a second impedance circuitry component coupled in parallel with the first impedance circuitry component. [Figure 6A] FIG. 4 is a diagram of an implementation of the sense coil circuitry of FIG. 3 including a first impedance circuitry component coupled between a first impedance circuitry node and a second impedance circuitry node, including a second impedance circuitry component coupled in parallel with the first impedance circuitry component, and including a third impedance circuitry component coupled between a first coil terminal and the first impedance circuitry node. [Figure 6B] FIG. 4 is a diagram of an implementation of the sense coil circuitry of FIG. 3 including a first impedance circuitry component coupled between a first impedance circuitry node and a second impedance circuitry node, including a second impedance circuitry component coupled in parallel with the first impedance circuitry component, and including a third impedance circuitry component coupled between a first coil terminal and the first impedance circuitry node. [Figure 7A] FIG. 4 is a Smith chart that may be utilized to determine elements of the impedance circuitry of FIGS. 4A-4C, 5A-5B, and 6A-6B. [Figure 7B] FIG. 4 is a Smith chart that may be utilized to determine elements of the impedance circuitry of FIGS. 4A-4C, 5A-5B, and 6A-6B. [Figure 7C]FIG. 4 is a Smith chart that may be utilized to determine elements of the impedance circuitry of FIGS. 4A-4C, 5A-5B, and 6A-6B. [Figure 7D] FIG. 4 is a Smith chart that may be utilized to determine elements of the impedance circuitry of FIGS. 4A-4C, 5A-5B, and 6A-6B. [Figure 8] FIG. 4 is a flow diagram illustrating an example of a routine for operating the inductive position transducer system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Figure 1 is a block diagram of an inductive position transducer system 10. As shown in Figure 1, the inductive position transducer system 10 includes a multi-signal transducer and driver / sensing circuit 12 that outputs an analog differential signal on signal lines 12A and 12B to an analog signal processor 70. The analog signal processor 70 outputs a differential signal on signal lines 70A and 70B to a lamp analog-to-digital converter 80. The lamp analog-to-digital converter 80 outputs a digital value over data line 80A to logic circuitry 90. The logic circuitry 90 sends and receives signals to and from the control unit 60 over a data and power bus 90A.

[0013] The control unit 60 also provides control signals to the multi-signal transducer and driver / sensing circuitry 12 via data and power bus 60A, to the analog signal processor 70 via data and power bus 60B, and to the lamp analog-to-digital converter 80 via data and power bus 60C. A low voltage power supply 50 may supply power to the entire inductive position transducer system 10 via one or more power lines 50A, with power further distributed via the various data and power buses of the system and under the control of the digital control unit 60. Further details regarding the operation and processing of an inductive position transducer system similar to that of FIG. 1 are described in U.S. Pat. No. 6,859,762, which is incorporated herein by reference in its entirety.

[0014] 1 illustrates a functional block diagram of inductive position transducer system 10, it will be understood that inductive position transducer system 10 is presented as one exemplary embodiment. It will be understood that the transducers in circuit 12 may be implemented using any suitable known or later developed multi-signal transducers, including, for example, the transducers disclosed in the incorporated '458 and '519 patents.

[0015] FIG. 2 is a block diagram of a more specific implementation of an inductive position transducer system 100, which may be an implementation of the system of FIG. 1. As described in more detail below, the inductive position transducer system 100 includes an inductive position transducer 108, which includes a magnetic field generating coil section including magnetic field generating coils A-C, a scale member 110, and a sensing coil section 120-n including a sensing coil. In one implementation, multiple three-phase transducer coils are used. FIG. 2 shows an example of a three-scale track design, where there are three sets of three-phase sensing coils. An example of a three-scale track design is further described in more detail in U.S. Pat. No. 6,304,832, which is incorporated by reference herein in its entirety.

[0016] 2, the inductive position transducer system 100 includes a magnetic field generating coil section 122 (e.g., comprising a magnetic field generating coil A) connected to a driver circuit 152. The first, second, and third sense coil sections 120-A1, 120-A2, and 120-A3 include a first sense coil 124, a second sense coil 126, and a third sense coil 127, respectively. The magnetic field generating coil A of the magnetic field generating coil section 122 is indirectly inductively coupled to the first sense coil 124, the second sense coil 126, and the third sense coil 127 of the first sense coil section 120-A1, the second sense coil section 120-A2, and the third sense coil section 120-A3 via a signal modulating element (e.g., including a conductive plate or a coupling loop, etc.) formed on the scale member 110 of the inductive position transducer 108.

[0017] According to the principles disclosed herein, each of the first, second, and third sense coil sections 120-A1, 120-A2, and 120-A3 sense coil sections is coupled to a first, second, and 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 position transducer 108 is coupled to a respective impedance circuit section 130-n. As described in more detail below (e.g., with respect to FIGS. 3-8), the inclusion of impedance circuit sections may provide certain desirable features (e.g., an increase in the signal available to the input circuit section, etc.). In various implementations, the input circuit section (described in more detail below, e.g., with respect to FIG. 3, etc.) coupled to the impedance circuit section 130-n may be included as part of a circuit following the impedance circuit section (e.g., one of the circuit sections 155, 170, etc., described in more detail below).

[0018] As shown in FIG. 2, the first impedance circuit section 130-A1, the second impedance circuit section 130-A2, and the third impedance circuit section 130-A3 are coupled to a multiplexer 155 (e.g., in some implementations, as described above, may include one or more respective input circuit sections, or one or more respective input circuit sections may alternatively be included in a subsequent circuit). The 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 the inputs of an analog-to-digital converter 180 on six output lines 170A-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 line 180A to a logic circuit 190 which processes the digital signal from the analog to digital converter 180 to determine the relative position between the read head (e.g. including a field generating coil portion and a sensing coil portion) and the scale member 110.

[0019] The inductive position transducer is configured to measure the displacement between two receiver coils. The position in the period (wavelength) of the periodic magnetic field generated by the two receiver coils, which varies with the change in the relative position between the two receiver coils of the inductive position transducer, can be uniquely identified by logic circuitry 190 according to known techniques and equations (e.g., as disclosed in the incorporated '458 and '519 patents). The wavelength is designed to match the spacing of the scale pattern of the inductive position transducer. Logic circuitry 190 also controls the sequence of signal sampling by outputting control signals to digital control unit 160 via signal lines 190A-190D. 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 lamp analog-to-digital converter 180.

[0020] In particular, as shown in FIG. 2, digital control unit 160 outputs control signals over power and signal bus lines 160A-160C to drivers 152-154, respectively, to controllably excite magnetic field generating coils A-C (i.e., magnetic field generating coil section 122 includes magnetic field generating coil A). Digital control unit 160 also outputs switch and control signals on power and signal bus lines 160D-160F to multiplexer 155. 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 circuitry 170 following multiplexer 155. A low voltage power supply 150 can provide power to the entire inductive position transducer system 100 over one or more power lines 150A, with power being further distributed over the various data and power buses of the system and under the control of digital control unit 160.

[0021] As mentioned above, FIG. 2 shows an example of a three scale track design, where there are three sets of three phase sensing coils. In various implementations, multiplexer 155 can select one signal, or one signal pair in the case of a differential measurement, 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 control signals on lines 160G and 160H. The output of analog signal processor 170 is provided on signal lines 170A-170F, which are input to analog-to-digital converter 180. Analog-to-digital converter 180 is controlled by a control signal on line 160I. Logic circuitry 190 has access to the output of analog-to-digital converter 180. Furthermore, since logic circuitry 190 controls the operation of digital control unit 160, logic circuitry 190 can select the scale tracks or phases in any order.

[0022] As described in more detail in U.S. Patent No. 6,304,832, which is incorporated herein by reference in its entirety, embodiments similar to those described above describing signal multiplexing between multiple phases of a single set of sensing coils apply equally well to multiplexing between multiple phases of two or more sets of multi-phase sensing coils. For example, in a three-scale track system as shown in FIG. 2, the input multiplexer 155 can select between nine possible phase pairs to process. These phase pairs can also be selected in a reverse polarity mode that effectively inverts the signal to cancel certain circuit errors. Thus, in various implementations, there can be a total of 18 possible ways to process the nine phase pairs of a three-scale track three-phase system.

[0023] FIG. 3 is a diagram of a sensing coil circuit section 300 of an inductive position transducer system such as that of FIGS. 1 and 2. As shown in FIG. 3, the sensing coil circuit section 300 includes a sensing coil section 320, an impedance circuit section 330, and an input circuit section 340 (which may be, for example, implementations of the sensing coil section 120-n, impedance circuit section 130-n, and input circuit section, respectively, as described above with respect to FIG. 2). The sensing coil section 320 (e.g., including a sensing coil) has a first coil terminal 321 and a second coil terminal 322. The sensing coil section 320 also includes a coil impedance (e.g., a coil impedance Z Rx ).

[0024] The sensing circuit section SCP includes an impedance circuit section 330 and an 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 coil terminal 321 and the second coil terminal 322 and has a first impedance circuit section node 331 and a second impedance circuit section node 332. The input circuit section 340 is connected to the first impedance circuit section node 331 and the second impedance circuit section node 332 and has an input impedance during operation (e.g., the input impedance may correspond to the impedance of a termination resistor RT of the input circuit section 340, as described in more detail below).

[0025] Input circuitry 340 is configured to receive an oscillating sense signal (e.g., resulting from a first sense coil signal from first sense coil section 320 passing through impedance circuitry 330) at first impedance circuitry node 331 and second impedance circuitry node 332. In various implementations, input circuitry 340 may represent an input of additional circuitry in an inductive position transducer system (e.g., as discussed above with respect to FIG. 2, in some implementations the additional circuitry may be included on an application specific integrated circuit (ASIC) and input circuitry 340 may represent an input of the ASIC).

[0026] As further shown in FIG. 3, the combined impedance portion (CIP) includes at least the first sense coil section 320 and the impedance circuit section 330 and has a combined impedance that is presented to the input circuit section 340 during operation. In various implementations, the components of the impedance circuit section 330 may be selected such that the combined impedance approximately matches, 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 itself, which typically does not match the input impedance of the input circuit section 340 well). As described in more detail below, FIGS. 4A-4C, 5A-5B, and 6A-6B show various examples of components that may be included in the impedance circuit section 330. Additionally, some example techniques for determining / selecting corresponding components are described in more detail below with respect to FIGS. 7A-7D.

[0027] 4A-4C are diagrams of implementations of the sense coil circuitry of FIG. 3. It will be understood that the features and operations described above with respect to FIG. 3 apply to the implementations of FIG. 4A-4C unless otherwise noted below. As shown in FIG. 4A, the sense coil circuitry 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., described in more detail below).

[0028] The sensing circuit portion (SCP') is configured to receive a first sensing coil signal from the first sensing coil portion 320. The sensing circuit portion SCP' includes an impedance circuit portion 330' and an input circuit portion 340. The impedance circuit portion 330' is connected to the first coil terminal 321 and the second coil terminal 322. The impedance circuit portion 330' includes a first impedance circuit portion component Z1 and a second impedance circuit portion component Z2. The first impedance circuit portion component Z1 is coupled between a first impedance circuit portion node 331 and a second impedance circuit portion node 332. The second impedance circuit portion component Z2 is coupled between the first coil terminal 321 and the first impedance circuit portion node 331.

[0029] The input circuitry 340 is connected to a first impedance circuit section node 331 and a second impedance circuit section node 332. The input circuitry 340, in operation, has an input impedance. In various implementations, the input impedance may correspond to the impedance of an input circuitry component ZT (which may be, for example, a termination resistor RT, as described in more detail below). As shown, the first impedance circuitry component Z1 is coupled in parallel with the input circuitry component ZT, such that the components are effectively coupled between the first impedance circuitry node 331 and the second impedance circuitry node 332, respectively. The input circuitry 340 is configured to receive an oscillating sense signal (e.g., resulting from a first sense coil signal from the first sense coil section 320 passing through the impedance circuitry 330′) at the first impedance circuitry node 331 and the second impedance circuitry node 332. The composite impedance portion CIP' includes at least the impedance circuit portion 330' and the first sense coil portion 320 and has a composite impedance that is presented to the input circuit portion 340 during operation.

[0030] 4B and 4C are more specific implementations of the sense coil circuit section 300' of FIG. 4A. FIG. 4B shows the sense coil circuit section 300A', and FIG. 4C shows the sense coil circuit section 300B'. As shown in FIG. 4B and 4C, the sense coil section 320 has an inductance and resistance (e.g., of the sense coil CL1) represented as an inductive portion 323 and a resistive portion 324. Correspondingly, the coil impedance Z of the sense coil section 320 (e.g., of the sense coil CL1) is Rx includes the inductance of inductive portion 323 and the resistance of resistive portion 324. As further shown in Figures 4B and 4C, in input circuit portion 340, input circuit portion component ZT is a termination resistor RT.

[0031] The voltage V of the sensing coil unit 320 Scorresponds to a signal induced in the sensing coil CL1 by operation of the inductive position transducer system (e.g., as described above with respect to FIGS. 1 and 2). More specifically, the drive signal is provided to the first magnetic field generating coil section (e.g., including a first magnetic field generating coil such as magnetic field generating coil 122 of FIG. 2) at an operating frequency to generate a changing magnetic flux that encompasses at least a portion of the first sensing coil section 320 (i.e., including a first sensing coil CL1, which in one example may be sensing coil 124 of FIG. 2). In various implementations, the voltage V S may correspond to a first sensing coil signal resulting from a changing magnetic flux induced current in the first sensing coil portion 320 (e.g., modified to varying degrees by a signal modulating element in the scale member depending on the relative position along the scale member, such that the first sensing coil signal is correspondingly indicative of the relative position between the first sensing coil portion 320 and a scale member, such as the scale member 110 of FIG. 2 of the inductive position transducer system). L corresponds to the resulting individual signal (e.g., across a termination resistor RT). In various implementations, the voltage V L may correspond to an oscillating sense signal at the first impedance circuit section node 331 and the second impedance circuit section node 332 (e.g., resulting from the first sense coil signal from the first sense coil section 320 passing through the impedance circuit section 330A' or 330B').

[0032] In the implementation of FIG. 4B, in the impedance circuit section 330A' of the sense coil circuit 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 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 those skilled in the art, in some implementations, the configuration of FIG. 4B may be characterized as corresponding to a high-pass filter configuration, and the configuration of FIG. 4C may be characterized as corresponding to a low-pass filter configuration. As one particular numerical example, in some implementations, the operating frequency during operation for the configuration may be 20 MHz.

[0033] It will be appreciated that in applications where it is desirable to attenuate low frequencies (e.g., attenuate low frequency noise), the configuration of FIG. 4B may be selected / utilized. Alternatively, in applications where it is desirable to attenuate high frequencies (e.g., attenuate high frequency noise), the configuration of FIG. 4C may be selected / utilized. In certain applications, much of the noise that is desirable to attenuate may typically be at higher frequencies. To that end, the configuration of FIG. 4C may be selected / utilized (e.g., as an alternative to certain other possible types of components / techniques for dealing with noise, with the added benefit of providing signal gain, as described in more detail below with respect to FIG. 7B).

[0034] 5A and 5B are diagrams of an implementation of the sense coil circuitry of FIG. 3. It will be understood that the features and operations described above with respect to FIGS. 3 and 4A-4C also apply to the implementation of FIGS. 5A and 5B, unless otherwise noted below. As shown in FIG. 5A, sense coil circuitry 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 and the input circuit section 340 are the same as those described above with respect to FIG. 4A. The main difference in the configuration of FIG. 5A compared to the configuration of FIG. 4A is the impedance circuit section 330'' compared to the impedance circuit section 330', as will be described in more detail below.

[0035] In the configuration of FIG. 5A , 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″ and an input circuit section 340. The impedance circuit section 330″ is connected to the first coil terminal 321 and the second coil terminal 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 such that it is coupled in parallel with the first impedance circuit section component Z1.

[0036] As described above, the input circuitry 340 is the same as that of FIG. 4A (e.g., has similar connections and operation) and is connected to the first impedance circuitry node 331 and the second impedance circuitry node 332. As shown, the first impedance circuitry component Z1 and the second impedance circuitry component Z2 are each coupled in parallel with the input circuitry component ZT, such that these components are effectively coupled between the first impedance circuitry node 331 and the second impedance circuitry node 332, respectively. The input circuitry 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 passing through the impedance circuitry 330'') at the first impedance circuitry node 331 and the second impedance circuitry node 332. The composite impedance portion CIP'' includes at least the impedance circuitry 330'' and the first sense coil section 320 and has a composite impedance that is presented to the input circuitry 340 during operation.

[0037] FIG. 5B is a more specific implementation of sense coil circuitry 300″ of FIG. 5A. The first sense coil section 320 and input circuitry 340 of FIG. 5B are the same as those described above with respect to FIGS. 4B and 4C. The main difference in the configuration of FIG. 5B compared to the configurations of FIGS. 4B and 4C is impedance circuitry 330″ compared to impedance circuitry 330A′ and 330B′, as described in more detail below.

[0038] In the implementation of FIG. 5B, in the impedance circuit portion 330″ of the sense coil circuit portion 300″, the first impedance circuit portion component Z1 is a capacitor C2 and the second impedance circuit portion component Z2 is a resistor R2. As described in more detail below (e.g., with respect to FIGS. 7A-7D), the desired selection of resistor R2 (i.e., in parallel with the termination resistor RT of the input circuit portion 340 as shown) may allow certain other match elements of the impedance circuit portion 330″ to be reduced to a single impedance circuit portion component Z1 (e.g., capacitor C2). As described in more detail further below, such a configuration may have some advantages (e.g., where the termination resistor RT may be relatively large, which may otherwise result in a relatively narrow bandwidth, the inclusion of resistor R2 may increase the bandwidth at the expense of some gain, and the wider bandwidth may be less sensitive to some component tolerances and sample timing for signals, etc.).

[0039] 6A and 6B are diagrams of an implementation of the sense coil circuitry of FIG. 3. It will be understood that the features and operations described above with respect to FIGS. 3, 4A-4C, 5A and 5B also apply to the implementation of FIGS. 6A and 6B, unless otherwise noted below. As shown in FIG. 6A, sense coil circuitry 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 and the input circuit section 340 are the same as those described above with respect to FIGS. 4A and 5A. The main difference in the configuration of FIG. 6A compared to the configuration of FIGS. 4A and 5A is the impedance circuit section 330''' compared to the impedance circuit sections 330' and 330'', as will be described in more detail below.

[0040] In the configuration of FIG. 6A , sensing circuit portion SCP′″ is configured to receive a first sensing coil signal from first sensing coil portion 320. Sensing circuit portion SCP′″ includes impedance circuit portion 330′″ and input circuit portion 340. Impedance circuit portion 330′″ is connected to first coil terminal 321 and second coil terminal 322. Impedance circuit portion 330′″ includes a first impedance circuit portion component Z1, a second impedance circuit portion component Z2, and a third impedance circuit portion component Z3. In impedance circuit portion 330′″, first impedance circuit portion component Z1 is coupled between first impedance circuit portion node 331 and second impedance circuit portion node 332. Second impedance circuit portion component Z2 is also coupled between first impedance circuit portion node 331 and second impedance circuit portion node 332 such that it is coupled in parallel with first impedance circuit portion component Z1. The third impedance circuit component Z3 is coupled between the first coil terminal 321 and a first impedance circuit node 331.

[0041] 4A and 5A (e.g., has similar connections and operation) and is connected to a first impedance circuit section node 331 and a second impedance circuit section node 332. As shown, a first impedance circuit section component Z1 and a second impedance circuit section component Z2 are each coupled in parallel with the input circuit section component ZT such that the components are 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 a first sense coil signal from the first sense coil section 320 passing through the impedance circuit section 330''') at the first impedance circuit section node 331 and the second impedance circuit section node 332. The composite impedance portion CIP''' includes at least the impedance circuit section 330''' and the first sense coil section 320 and has a composite impedance that is presented to the input circuit section 340 during operation.

[0042] FIG. 6B is a more specific implementation of sense coil circuitry 300''' of FIG. 6A. The first sense coil section 320 and input circuitry 340 of FIG. 6B are the same as those described above with respect to FIGS. 4B, 4C, and 5B. The main difference in the configuration of FIG. 6B compared to the configurations of FIGS. 4B, 4C, and 5B is impedance circuitry 330''' compared to impedance circuitry 330A', 330B', and 330'', which will be described in more detail below.

[0043] In the implementation of FIG. 6B, in impedance circuitry 330''' of sense coil circuitry 300''', the first impedance circuitry component Z1 is a capacitor C3A, the second impedance circuitry component Z2 is a resistor R3, and the third impedance circuitry component Z3 is a capacitor C3B. As described in more detail below (e.g., with respect to FIGS. 7A-7D), impedance circuitry 330''' may have some advantages similar to those of impedance circuitry 330' of FIG. 4A, although the addition of resistor R3 may provide some additional advantages (e.g., allowing for a wider bandwidth). In various implementations, the configuration of FIG. 6B may be characterized as providing three degrees of freedom in which component values ​​may be selected to produce a desired resonant frequency, peak gain, and / or bandwidth (e.g., with a corresponding phase slope).

[0044] As discussed above in connection with the examples of FIGS. 4A-4C, 5A-5B, and 6A-6B, in various implementations, the coil impedance Z of the sensing coil section 320 is Rx may include the impedance of the inductive portion 323 (e.g., of the sense coil CL1) and the resistive portion 324. The impedance of the input circuitry 340 may include the impedance of the input circuitry components ZT (which may include, e.g., a termination resistor RT), and in some implementations may be referred to as the input impedance. In various implementations, the coil impedance Z of the sense coil portion 320 combined with the impedance of the impedance circuitry 330 may be RxBy closely matching, or at least coming close to matching, the impedance of the input circuitry 340 (e.g., by matching the impedance of the input circuitry 340 more closely than the coil impedance of the sensing coil section 320 itself), the signal available to the input circuitry 340 can be effectively increased (e.g., in some examples, by a relatively large amount), resulting in an increased signal-to-noise (SNR) ratio and / or the ability to reduce the magnetic field generating power (e.g., the magnetic field generating power of a magnetic field generating section that includes one or more magnetic field generating coils such as those utilized to induce current in the sensing coil CL1 as part of the inductive position transducer operation as described above with respect to FIG. 2).

[0045] As described herein, the composite impedance includes the composite reactance and the composite resistance of the sense coil section 320 and the impedance circuit section 330. The components of the impedance circuit section 330 may be configured such that the composite impedance approximately matches, or at least comes closer to matching, the impedance of the input circuit section 340 (e.g., closer to matching than the sense coil section 320 itself). With respect to the composite reactance, in various implementations, by inserting elements into the impedance circuit section 330 to achieve an approximate match, or at least comes closer to matching, the composite reactance (e.g., at the operating frequency utilized during operation) including the reactance of the inductive section 323 of the sense coil section 320 can be effectively reduced or eliminated (e.g., to approximately match, or at least comes closer to matching, the reactance of the input circuit section 340, which may have little or no reactance due to having mainly only a termination resistor RT). In addition, the combined resistance including the resistance of the resistor portion 324 of the sense coil portion 320 can be effectively transformed to approximately match (e.g., approximately equal to) or at least closely match the resistance of the input circuit portion 340 (e.g., including the resistance of the termination resistor RT). Smay appear relatively high (e.g., due to closer to resonance characteristics, etc.). Such an embodiment may substantially maximize or otherwise increase power transfer from the sense coil portion 320 (e.g., including the sense coil CL1) to the input circuit portion 340 (e.g., including the termination resistor RT).

[0046] Various techniques may be utilized to determine the elements (e.g., components) of the impedance circuitry 330 for such purposes. For example, in one implementation, complex algebra may be utilized to determine the elements (e.g., having corresponding values) of the impedance circuitry 330 (e.g., to achieve an approximate match, or at least a closer match, as described above). In such an implementation, some common expressions for impedance Z and admittance Y are shown by Equation 1 and Equation 2 below, respectively. Z=R+jX (formula 1) where j=(-1) 1 / 2 It is. Y=1 / Z=G+jB (Equation 2)

[0047] In general, for elements within an impedance circuit section (e.g., as in the examples of Figures 4A-4C, 5A-5B, and 6A-6B), the insertion / inclusion of a series element corresponds to the addition of an impedance, and the insertion / inclusion of a parallel element corresponds to the addition of an admittance. In various implementations, two or more elements may be inserted / included in the impedance circuit section.

[0048] 7A-7D are diagrams of Smith charts as may be utilized in some examples to determine impedance circuitry elements such as those of FIGS. 4A-4C, 5A-5B, and 6A-6B. In various implementations, such Smith charts may be utilized as an aid to visualize matching solutions, but may comprise polar plots of reflection coefficients. As shown in FIG. 7A, superimposed on the plots are impedance and admittance grids (e.g., impedances are indicated by correspondingly labeled interior dotted circles and similar interior dotted curves, and admittances are indicated by correspondingly labeled interior solid circles and similar interior solid curves). Note that in these examples, the charts are normalized, where all impedances are purely resistive and divided by a characteristic impedance Z0, which is set equal to the resistance of the input circuitry component ZT (e.g., set equal to the resistance of the termination resistor RT). The normalized characteristic impedance z0 is represented by a small square in the center of each of the charts (e.g., in various implementations, may be characterized as representing a relative target for close matching as described above). Equations 3-5 below (e.g., related to Equations 1-2 above) show specific relationships for the characteristic impedance Z0. z0=1+j0 (Equation 3) z=Z / Z0=r+jx (Eq. 4) y=Z0 / Z=g+jb (Equation 5)

[0049] In FIG. 7A, the solid circle inside the admittance represents g=1, where g is the real part of the admittance, and the dotted circle inside the impedance represents r=1. In various implementations, for the examples described herein, the solid circle inside the admittance may be considered one of the relatively more important curves in the chart. The impedance z of the coil Rxcorresponds to the impedance of the sense coil section 320. As mentioned above, in various implementations, it may be considered desirable for the combined impedance of the sense coil section and the impedance circuit section to be close to (e.g., in some cases approximately matching) a characteristic impedance z0 that is purely resistive and set equal to the resistance of the termination resistor RT (e.g., corresponding to the small square in the center of the chart labeled "1" and where z0=1+j0 according to Equation 3). Thus, as described in more detail below with respect to the examples of FIGS. 7B-7D, the elements of the impedance circuit section may be determined / selected to move their representations along their respective curves of the Smith chart to bring the combined impedance closer to (e.g., approximately matching in some cases) the small central square (i.e., to represent a characteristic impedance z0 equal to the resistance of the termination resistor RT). It should be noted that the charts of FIGS. 7B-7D include all of the same illustrated features of the chart of FIG. 7A, as well as additional illustrated features, as described in more detail below.

[0050] With respect to FIG. 7B, the illustrated exemplary charts in various implementations may correspond to the exemplary impedance circuitry of FIGS. 4A-4C, as described in more detail below. In these particular examples, the elements (e.g., components) of the impedance circuitry include only capacitors and inductors. As a result, the impedance and admittance in the charts of FIG. 7B only move on circles of constants r and g. Resistors are not used in these examples (e.g., resistors may introduce losses, but resistors may alternatively be used in some other implementations, such as with the example of FIG. 7D, which may correspond to the examples of FIGS. 5A, 5B, 6A, and / or 6B, as described in more detail below). In the example of FIG. 7B, the following equations may be utilized to convert between impedance z and reflection coefficient r. In various implementations, these may be used to generate polar plots (e.g., in math software, etc.). r=(z-1) / (z+1) (Eq. 6a) z=(1+r) / (1-r) (Equation 6b)

[0051] The impedance Z of the sensing coil unit 320 is Rx and the resistance of the termination resistor RT, and the operating frequency is 20 MHz. Z Rx =(0.97+j7.21)Ω@20MHz (Equation 7) Here, 0.97 ohms is the impedance (e.g., including resistance) of resistive portion 324, and j7.21 ohms is the impedance (e.g., including reactance) of inductive portion 323. In general, the impedance of an inductor and / or an inductive portion is given by Z=j * ω * L, where ω=2 * π * In this example (e.g., if the operating frequency is 20 MHz and the inductance of the inductive part 323 is L=57.4 nH), the calculation is Z=j * 2 * π * 20,000,000 * 57.4 * It can be expressed as 10^(-9)=j7.21Ω.

[0052] The resistance of the termination resistor RT is 500Ω (i.e. 500 ohms). Therefore, according to the above technique, Z0=500Ω and the normalization is performed as follows: z Rx =Z Rx / Z0=0.00194+j0.0144 (Equation 8) y Rx =1 / z Rx =9.16-j68.12 (Equation 9)

[0053] In the example of FIG. 7B, g=9.16 corresponds to the inner circle of g=1 (e.g., shown in FIG. 7B as a smaller dotted circle within the circle corresponding to g=1), so in various implementations, this indicates that reaching r=1 may not generally be achieved by adding parallel elements. This is because the first element reduces the coil impedance z Rx(e.g., with a first element, such as corresponding to impedance circuit component Z2 in the example of FIG. 4A ). In various implementations, Rx The composite impedance (including the impedances r, g, and r) can be moved along the circle r=0.00194 until it achieves an intercept g=1. The circle r=0.00194 is represented in FIG. 7B as a relatively large dashed circle (i.e., approximately the same size as the chart) and its value is shown in Equation 8. In the representation in FIG. 7B, the circle r=0.00194 intercepts the circle g=1 in two places, indicating that two solutions exist.

[0054] As a first solution (e.g., “solution a”) corresponding to the example of FIG. 4B, a series capacitor C1A is inserted / included, which in the example of FIG. 7B is inserted such that g=1 (i.e., z Rx 7B ) toward the capacitive side of the chart (as shown by the curved downward arrow labeled "cap" that extends downward from the end of the "cap" arrow and intersects with circle g=1 along circle r=0.00194). In addition, a parallel inductor L1A is inserted / included (e.g., in parallel with the input circuitry component ZT), which in the example of FIG. 7B , moves the composite admittance counterclockwise along circle g=1 to r=1 (i.e., as shown by the curved rightward and upward arrow labeled "ind" that extends from the end of the "cap" arrow, proceeds counterclockwise along circle g=1, and approximately intersects with circle r=1 at the small central square "1"). As discussed above, the small central square corresponds to a normalized characteristic impedance z0 corresponding to the termination resistor RT, and thus the configuration of FIG. 4B (e.g., having characteristics as shown in FIG. 7B) at least approximately achieves a desired match, such as reactance, which, as discussed above, may be relatively minimal (e.g., composite reactance is relatively reduced and / or eliminated).

[0055] As a second solution (e.g., “solution b”) corresponding to the example of FIG. 4C, a series inductor L1B is inserted / included, which is such that g=1 (i.e., zRx 4C ) and moves the combined impedance more toward the inductive side of the chart (as shown by the curved upward dashed arrow labeled "ind" that extends upward from the end of the "ind" arrow and intersects with the circle g=1 along the circle r=0.00194). In addition, a parallel capacitor C1B is inserted / included, which in the example of FIG. 7B moves the combined admittance clockwise along g=1 to r=1 (i.e., as shown by the curved rightward and downward dashed arrow labeled "cap" that extends from the end of the "ind" arrow, proceeds clockwise along the circle g=1, and approximately intersects with the circle r=1 at the small central square "1"). As discussed above, the small central square "1" corresponds to the normalized characteristic impedance z0 as corresponding to the termination resistor RT, and thus the configuration of FIG. 4C (e.g., having the characteristics as shown in FIG. 7B ) at least approximately achieves the desired match, such as reactance, which may be relatively minimal (e.g., the combined reactance is relatively reduced and / or eliminated), as discussed above.

[0056] In conjunction with the above concepts, various calculations described below show the determination of values ​​for specific components. As a first calculation, the series reactance x1 can be calculated such that the resulting admittance has g=1. The following formula assumes a capacitive reactance: 1 / (z Rx -jx1)=1+jb (Equation 10)

[0057] Using known algebraic techniques, two solutions can be found, as shown below: x1=x Rx ±(rr 2 ) 1 / 2 =0.0584 or -0.0296 (Equation 11)

[0058] The positive result represents the reactance of capacitor C1A (ie, in FIG. 4B) and the negative result represents the reactance of inductor L1B (ie, in FIG. 4C), with example values ​​as shown below: C1A=1 / (0.0584·ωZ0)=272pF (Equation 12) L1B=-(-0.0296)Z0 / ω=118nH (Equation 13)

[0059] The admittance after inserting x1 is shown below. y1=1 / (Z Rx -jx1)=1±j22.68 (Equation 14)

[0060] Parallel elements having susceptance b=±22.68 are shown below, and the parallel elements in these examples include inductor L1A (i.e., in FIG. 4B) and capacitor C1B (i.e., in FIG. 4C) having exemplary values ​​shown below. L1A=Z0 / (22.68ω)=175nH (Equation 15) C1B=22.68 / (ωZ0)=361pF (Equation 16)

[0061] Using the example values ​​as above, an example voltage gain for both the configurations of FIG. 4B and FIG. 4C may be approximately 11.35 (21.1 dB) (which may be compared to a gain of 1.0 for an "unmatched" circuit that does not include impedance circuit portion 330, for example). Thus, a relatively large increase in gain may be achieved utilizing configurations as disclosed herein. In various implementations, the frequency response for each configuration may be calculated based on a voltage divider equation as shown below: V L =V S (Z b (ω)) / (Z b (ω)+Z a (ω)) (Equation 17)

[0062] In Equation 17, the voltage V L and V S may be as shown in FIG. 4B and FIG. 4C , and Z b (ω) may represent the combination of circuit elements L1A and RT in FIG. 4B or circuit elements C1B and RT in FIG. 4C, respectively, and Z a(ω) may represent a combination of circuit elements CL1 and C1A in FIG. 4B, or circuit elements CL1 and L1B in FIG. 4C. It will be appreciated that in the configuration of FIG. 4B, low frequencies may be attenuated, but the 3dB bandwidth may be 242kHz, and the phase slope may be -0.756deg / 10KHz, as some exemplary values. It will be appreciated that in the configuration of FIG. 4C, high frequencies may be attenuated (e.g., as may be advantageous to suppress certain electromagnetic interference from external sources, etc.), but the 3dB bandwidth may be 336kHz, and the phase slope may be -0.543deg / 10KHz. It will be appreciated that the configuration of FIG. 4B or FIG. 4C (or a similar configuration) may thus be selected for a particular application (e.g., utilizing the configuration of FIG. 4B or FIG. 4C to attenuate low or high frequencies, respectively) depending on the characteristics required.

[0063] FIG. 7C shows a chart similar to that of FIG. 7B, but with some differences, as noted below. The main difference is that in the example of FIG. 7C, the coil impedance z Rx is shown as being outside the circle g=1. In various implementations, both g=1 and r=1 are reachable, so this may indicate four possible solutions. Two of the solutions allow for the use of only capacitors in the impedance circuit portion, and the other two solutions include inductors. The two potential solutions that include only capacitors are described in more detail below.

[0064] With reference to FIG. 4A, for the two solutions utilizing only capacitors, in impedance circuit portion 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 of FIG. 4A), which in the example of FIG. 7C moves the composite impedance down (i.e., z Rx4A ) and intersects with circle g=1 along circle r=0.00194). In addition, a parallel capacitor is inserted / included (e.g., as component Z1 in FIG. 4A , in parallel with input circuitry component ZT), which in the example of FIG. 7C moves the coupling admittance clockwise along circle g=1 to r=1 (i.e., as shown by the curved rightward and downward arrow labeled "cap" that extends from the end of the first "cap" arrow, proceeds clockwise along circle g=1, and approximately intersects with circle r=1 at the small center square "1"). As discussed above with respect to FIG. 7B , such a characteristic at least approximately achieves a desired match, such as reactance, which may be relatively minimal (e.g., with composite reactance relatively reduced and / or eliminated), as discussed above.

[0065] As a second solution, a parallel capacitor is inserted / included (e.g., as a second impedance circuit component Z2), which in the example of FIG. 7C shifts the composite impedance toward the right to reach circle r=1 (i.e., z Rx4A where component Z2 is in series with component ZT and component Z1 is in parallel with component ZT, as the first impedance circuit part component Z1 has a similar connection of impedance circuits, such as component Z2 is in parallel to the right of component Z2 and component Z1 is in series with component Z2 but includes component ZT coupled / connected between first impedance circuit part node 331 and second impedance circuit part node 332). This configuration of the second solution (i.e., the example of FIG. 7C) moves the resultant admittance counterclockwise along r=1 to reach the central square "1" (i.e., as shown by the curved downward dashed arrow labeled "cap" that extends from the end of the other "cap" arrow and traces counterclockwise along the circle r=1 to the small central square "1").

[0066] With respect to FIG. 7D, the illustrated example chart in various implementations may correspond to the example impedance circuitry of FIG. 5A and FIG. 5B, as described in more detail below. As mentioned above, one difference from the configurations of FIG. 4B and FIG. 4C is that in the configuration of FIG. 5B, the impedance circuitry 330″ includes a resistor R2 (e.g., as the second impedance circuitry component Z2). In some implementations, the resistor R2 may be characterized as essentially modifying the effective input impedance of the input circuitry 340 (e.g., the parallel resistors R2 and RT provide a combined resistance that is lower than the combined resistance of the resistor RT itself). In some implementations, such as the chart of FIG. 7D, it may be considered to be purely resistive and to lower the effective characteristic impedance Z0, which is set equal to the effective input resistance (e.g., in this example, it may include the combined resistance of the parallel resistor R2 and the termination resistor RT). As mentioned above, the chart is normalized, and all impedances are divided by the characteristic impedance Z0. As mentioned above, the normalized characteristic impedance z0 is represented by the small square "1" in the center of the chart.

[0067] Further to the chart of FIG. 7D, for admittance, g=1 is set in this equation. Y=Z0 / Z Rx =1+jb (Equation 18)

[0068] This has the following solution: Z0 = R + (ωL) 2 / R (Formula 19) b=-ωL / R (Eq. 20)

[0069] The parallel resistors R2 in the configuration of FIG. 5B are as follows: R2=1 / (1 / Z0-1 / RT) (Equation 21)

[0070] Finally, a parallel capacitor C2 is inserted for at least an approximate match: C2=-b / (ωZ0) (Equation 22)

[0071] 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 (e.g., in which case the component values ​​may be calculated using techniques similar to those described above). The values ​​of other components may be similar to those in the above example (e.g., inductive portion 323 has an inductance of 57.4 nH, resistive portion 323 has a resistance of 0.97 ohms, 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 termination resistor RT may be relatively high (e.g., equal to 4 kilohms). In various implementations, when the resistance of termination resistor RT is significantly larger than the resistance of resistive portion 324, the reactance of the matching components may be very large and relatively sensitive to tolerances. In some implementations (e.g., as shown in FIG. 6B), a parallel resistor R2 can be combined with the configuration of FIG. 4A (e.g., when two capacitors are utilized as components Z1 and Z2, as shown in the chart of FIG. 7C) to target a desired gain, as described in more detail below.

[0072] Using the above example values ​​of components (e.g., using the combined resistance of resistor R2 in parallel with termination resistor RT), the effective characteristic impedance Z0 is reduced to 54.6 ohms. In this example, this is a relatively large reduction from the original 500 ohm value of termination resistor RT itself, but the voltage gain is still 3.75 (11.5 dB). The reduction in effective characteristic impedance Z0 also reduces the thermal noise in termination resistor RT. As some further example values ​​for the configuration of FIG. 5B, the 3 dB bandwidth may be 872 kHz and the phase slope may be -0.213 deg / 10 KHz.

[0073] In an alternative implementation where the goal is resonance rather than a near match, a configuration similar to that of FIG. 4C (e.g., except for the absence of series inductor L1B) may be used, in which parallel capacitor C1B is used to set the resonant peak voltage at the target frequency. It should be noted that the matching technique as described above can produce configurations with relatively higher voltage gains than configurations more geared toward resonance. For example, as discussed above, the configuration of FIG. 4C in one particular implementation may have a voltage gain of about 11.35 (21.1 dB), while a similar resonant version (e.g., without inductor L1B and with a different value for parallel capacitor C1B), described in more detail below, 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 matched version.

[0074] As noted above, in a resonant version of a configuration similar to that of FIG. 4C (e.g., including parallel capacitor C1B but not series inductor L1B), the parallel capacitor C1B is utilized to set the resonant peak voltage at the target frequency. For such a version, a simplified technique for calculating an approximation of the parallel capacitor C1B may utilize the classical formula for resonating an LC tank circuit (as part of the simplification, the effect of resistive portion 324 and termination resistor RT on the resonant peak is calculated using ω=1 / (LC) for the inductance L and capacitance C of the LC tank circuit: 1 / 2 (This is ignored in the following simplified formula, which follows the general form: ω=1 / ((L 323 )(C1B)) 1 / 2 (Formula 23) Here, L 323 is the inductance of the inductive part 323, and according to the other example values ​​above, ω=2 * π * frequency, the operating frequency is 20 MHz, and the inductance of the inductive part 323 is L=57.4 nH, as follows: C1B=1 / ((ω 2 )(L 323 ))=1.104nF (Equation 24)

[0075] As part of a more detailed calculation of the value of C1B to achieve resonance (e.g., considering the effects of resistive portion 324 and termination resistor RT, setting the derivative of voltage with respect to frequency to zero, and utilizing relatively complex algebra as will be understood by those skilled in the art), a more accurate value in this example may be determined as C1B=1.094 nF (e.g., this may place the resonant peak exactly at the target frequency). Utilizing this value for such an exemplary resonant version may result in a voltage gain of approximately 6.75 (16.5 dB) at an operating frequency of 20 MHz. A version utilizing a value of C1B=1.104 nF from Equation 24 (note that this is relatively close to the more accurate value) may result in a slightly lower voltage gain and the voltage peak may be slightly offset from the target frequency. In any case, as discussed above, in these particular examples, the voltage gain of such a resonant version may be relatively less (e.g., may be 60 percent or less) than the voltage gain of a version formed using the matching principles discussed above with respect to FIG. 4C (i.e., having a voltage gain of approximately 11.35 (21.1 dB)).

[0076] Further, with respect to configurations utilizing the matching principle as described above, it is noted that Figure 6B illustrates another configuration having certain desirable properties. In some implementations, the configuration of Figure 6B can be described as combining the configuration of Figure 4A (i.e., having capacitors as components Z1 and Z2) with a parallel resistor R3 (e.g., similar to the parallel resistor R2 of Figure 5B). It will be appreciated that a configuration such as Figure 6B can have properties such as a wider bandwidth and reduced phase slope (e.g., compared to other exemplary configurations described above).

[0077] As some specific numerical examples for the configuration of FIG. 6B, with resistor R3 having a value of 51 ohms and with the combined resistance of resistor R3 in parallel with the termination resistor RT, the effective characteristic impedance Z0 is reduced to 46.3 ohms. Such a configuration can be moved / resulted in a similar manner to the example described above with respect to the chart of FIG.Rx may be outside the circle g = 1. Correspondingly, components Z1 and Z3 of Figure 6A may be implemented as capacitors (e.g., as described above with respect to the chart of Figure 7C and as shown in Figure 6B for respective capacitors C3A and C3B).

[0078] As some specific example values, in one configuration, the capacitance of capacitor C3A may be 1.175 nF, while the capacitance of capacitor C3B may be 13.7 nF (e.g., for which component values ​​may be calculated using techniques similar to those described above with respect to FIG. 7C). The values ​​of other components may be similar to those in the above example (e.g., inductive portion 323 has an inductance of 57.4 nH, resistive portion 323 has a resistance of 0.97 ohms, termination resistor RT has a resistance of 500 ohms, resistor R3 has a resistance of 51 ohms, etc.). With such example values, an example voltage gain of the configuration of FIG. 6B may be about 3.45 (10.8 dB), the 3 dB bandwidth may be 2.04 MHz, and the phase slope may be −0.089 deg / 10 KHz. It should be noted that in various implementations, the configuration of FIG. 6B may effectively widen the bandwidth and reduce the phase slope (e.g., relative to other example configurations described above). For example, as discussed above with respect to certain possible example component values, the configuration of FIG. 4B may have characteristics such that the 3 dB bandwidth may be 242 kHz and the phase slope may be -0.756 deg / 10 KHz. The configuration of FIG. 4C may have characteristics such that the 3 dB bandwidth may be 336 kHz and the phase slope may be -0.543 deg / 10 KHz. The configuration of FIG. 5B may have characteristics such that the 3 dB bandwidth may be 872 kHz and the phase slope may be -0.213 deg / 10 KHz. (Note, for example, that all of these have narrower bandwidths and steeper phase slopes than the example configuration of FIG. 6B, as discussed above.)

[0079] The following includes a comparison of some of the features of the example configurations of Figures 4A-4C and 6A-6B discussed above (e.g., different features may be desirable depending on the particular application). Note that the example configurations of Figures 4A-4C have the highest gain of the examples (e.g., in some implementations, representing the upper limit of the gain that may be achieved), but the configurations also generally have the smallest bandwidth and steepest phase slope. The example configurations of Figures 6A-6B generally illustrate that component values ​​may be selected to generally target a particular desired gain, or bandwidth, or slope (e.g., having a maximum gain as illustrated by the examples of Figures 4A-4C above). In various implementations, a relatively large bandwidth (e.g., that of the exemplary configuration of FIG. 6B ) can help minimize problems due to slight shifts in the resonant peak (e.g., due to slight changes / differences in the characteristics of the sensing coil CL1 including the inductive portion 323 and / or resistive portion 324 and / or component tolerances, which may be due to gap variations and / or position on the scale of the overall inductive position transducer, such as those described above with respect to FIG. 2 ).

[0080] In particular, note that the exemplary configuration of FIG. 6B has an impedance circuit portion 330''' that includes three relatively inexpensive components (e.g., capacitors C3A and C3B, and resistor R3). This configuration may be repeated for different phases across the inductive position transducer (e.g., as described above with respect to FIG. 2). In some implementations, the use of only capacitors and resistors (e.g., as shown in FIG. 6B) may be preferred over a configuration that utilizes inductors (e.g., as shown in FIGS. 4A and 4B), such as because component tolerances for capacitors and resistors in some implementations are generally better / consistent than those for inductors, etc. In various implementations, it may be desirable to utilize relatively low temperature coefficient (TC) components (e.g., NPO ceramic capacitors, etc.). In general, the maximum possible gain increases as ωL / R increases and / or RT / R 324 When increases (for example, where R 324Note that, the resistance of resistive portion 324, i.e., .times. ...

[0081] As mentioned above, as a specific numerical example, in various implementations of any of the configurations described herein, the operating frequency may be 20 MHz. With respect to the matching technique as described above, it may generally be desirable to utilize such a relatively high operating frequency (e.g., so that the matching technique may be relatively more effective at a relatively high operating frequency for desired benefits). Also, it should be noted that configurations having / utilizing a relatively large / high value termination resistor RT may have relatively greater flexibility with respect to the matching technique.

[0082] 8 is a flow diagram illustrating an example routine 800 for operating an inductive position transducer system (e.g., including impedance circuitry as described herein). In block 810, a drive signal is provided to a first magnetic field generating coil section at an operating frequency to generate a changing magnetic flux encompassing at least a portion of a first sensing coil section, the first sensing coil section having a first coil terminal, a second coil terminal, and a coil impedance. In block 820, a first sensing coil signal indicative of a relative position between the first sensing coil section and the scale member is received from the first sensing coil section in the sensing circuitry. In various implementations, the first sensing coil signal results from a changing magnetic flux induced current in the first sensing coil section, modified by a signal modulating element of the scale member to various degrees depending on the relative position along the scale member, in response to which the first sensing coil signal correspondingly indicates a relative position between the first sensing coil section and the scale member.

[0083] The sensing circuitry comprises an impedance circuitry connected to the first coil terminal and the second coil terminal, and an input circuitry. The impedance circuitry comprises a first impedance circuitry component and a second impedance circuitry component. The first impedance circuitry component is coupled between a first impedance circuitry node and a second impedance circuitry node. The second impedance circuitry is at least one of coupled between the first impedance circuitry node and the second impedance circuitry node and coupled between the first coil terminal and the first impedance circuitry node. The input circuitry is connected to the first impedance circuitry node and the second impedance circuitry node, the input circuitry having an input impedance during operation. The input circuitry is configured to receive an oscillating sense signal (e.g., resulting from a first sense coil signal received at the sensing circuitry) at the first impedance circuitry node and the second impedance circuitry node. A composite impedance portion comprising at least the impedance circuitry and the first sense coil section has a composite impedance presented to the input circuitry during operation.

[0084] In various implementations, the method may further include determining a relative position between the first sense coil section and the scale member (e.g., as corresponding to a relative position between the readhead and the scale member) based at least in part on the oscillating sense signals received at the first impedance circuit section and the second impedance circuit section. In various implementations, determining the relative position between the first sense coil section and the scale member may correspond to / be accomplished by determining the relative position between the readhead and the scale member. As discussed above, the readhead may include multiple sense coil sections and impedance circuit sections (e.g., sense coil sections 120-n and impedance circuit sections 130-n of FIG. 2), and determining the relative position between the readhead and the scale member (e.g., scale 110 of FIG. 2) may be based at least in part on processing and / or otherwise combining multiple oscillating sense signals received at multiple corresponding first impedance circuit section and second impedance circuit section nodes.

[0085] The following describes some example embodiments of the present disclosure having various features and elements annotated with reference numbers found in Figures 1-8. It should be understood that these reference numbers are added to illustrate example embodiments and that the features and elements are not limited to the specific embodiments illustrated in Figures 1-8.

[0086] An inductive position transducer system 100 is provided that includes an inductive position transducer 108 and sensing circuitry SCP. In various implementations, a sensing circuitry SCP is provided for each sensing coil section 120-n (e.g., each sensing coil) of the inductive position transducer 108.

[0087] The inductive position transducer 108 comprises at least a first sensing coil section 320 / 120A1 (e.g., having a first sensing coil) having 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 comprises an impedance circuit section 330 / 130-A1 and an input circuit section 340 (e.g., of an application specific integrated circuit (ASIC)).

[0088] The impedance circuit section 330 is connected to the first coil terminal 321 and the second coil terminal 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.

[0089] An input circuit section 340 (e.g., of an ASIC) is connected to the first impedance circuit section node 331 and the second impedance circuit section node 332. The input circuit section 340 has an input impedance during operation (e.g., while an operating frequency is utilized), and the input circuit section 340 is configured to receive an oscillating sense signal at the first impedance circuit section node 331 and the second impedance circuit section node 332. A composite impedance portion CIP comprising at least the impedance circuit section 330 and the first sense coil section 320 has a composite impedance that is presented to the input circuit section 340 (e.g., of an ASIC) during operation.

[0090] In various implementations, the sense coil section 320 comprises a sense coil CL1 comprising a first coil terminal 321, a second coil terminal 322, and a coil impedance. The sense coil CL1 comprises an inductive portion 323 and a resistive portion 324. The input impedance of the input circuit section 340 includes an impedance of an input circuit section component ZT coupled between a first impedance circuit section node 331 and a 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 FIGS. 6A and 6B), the impedance circuit section 330''' may further comprise a third impedance circuit section component Z3 coupled between the first coil terminal 321 and the first impedance circuit section node 331. In various implementations, the third impedance circuit section component Z3 comprises a capacitor C3B.

[0091] In various implementations, the sense coil section 320 includes an inductive section 323 having an associated reactance in operation that would otherwise be presented to the input circuit section 340, but as a result of including an impedance circuit section 330 (e.g., FIGS. 4A-4C, 5A-5B, and 6A-6B) in the composite impedance section CIP, a large portion of the reactance in the composite impedance is eliminated. In various implementations, one or more impedance circuit section components of the impedance circuit section are configured to eliminate a large portion of the reactance of the inductive portion of the sense coil section.

[0092] It will be appreciated 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 referenced herein are incorporated herein by reference in their entirety. Aspects of the implementations may be modified, if necessary, to use concepts from the various patents and applications to provide further implementations. These and other changes can be made to the implementations in light of the above detailed description. In general, the terms used in the following claims should not be construed to limit the scope of the claims to the specific implementations disclosed in the specification and claims, but should be construed to include all possible implementations along with the full scope of equivalents to which such claims are entitled.

Claims

1. 1. An inductive position transducer system comprising: an inductive position transducer comprising a first sensing coil section having a first coil terminal, a second coil terminal, and a coil impedance; a sensing circuit section configured to receive a first sensing coil signal from the first sensing coil section, an impedance circuit section connected to the first coil terminal and the second coil terminal, a first impedance circuit component coupled between the first impedance circuit node and a second impedance circuit node; and a second impedance circuit component, coupled between the first impedance circuit portion node and the second impedance circuit portion node; or a second impedance circuit component coupled between the first coil terminal and the first impedance circuit node; An impedance circuit unit comprising: an input circuitry coupled to the first impedance circuitry node and the second impedance circuitry node, the input circuitry having an input impedance during operation and configured to receive an oscillation sensing signal at the first impedance circuitry node and the second impedance circuitry node; A sensing circuit section comprising: Equipped with A composite impedance portion comprising at least the impedance circuit portion and the first sensing coil portion has a composite impedance presented to the input circuit portion during operation.

2. The system of claim 1 , wherein the sensing coil section comprises a sensing coil comprising 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. 2. The system of claim 1, wherein the input impedance of the input circuitry comprises an impedance of an input circuitry component coupled between the first impedance circuitry node and the second impedance circuitry node.

5. The system of claim 4 , wherein the input circuitry component comprises a resistor.

6. The system of claim 1 , wherein the second impedance circuit component is coupled between the first impedance circuit node and the second impedance circuit node.

7. The system of claim 6 , wherein the impedance circuit further comprises a third impedance circuit component coupled between the first coil terminal and the first impedance circuit node.

8. The system of claim 7 , wherein the third impedance circuit component comprises a capacitor.

9. The system of claim 1 , wherein the first impedance circuit component comprises one of a capacitor or an inductor.

10. The system of claim 9 , wherein the first impedance circuit component comprises a capacitor.

11. The system of claim 9 , wherein the second impedance circuit component comprises one of a capacitor, an inductor, or a resistor.

12. The system of claim 11 , wherein the second impedance circuit component comprises a resistor.

13. 13. The system of claim 12, wherein the first impedance circuit component comprises a capacitor, and the second impedance circuit component is coupled between the first impedance circuit node and the second impedance circuit node.

14. 2. The system of claim 1, wherein the sensing coil section comprises an inductive portion having an associated reactance in operation, the reactance being largely eliminated in the composite impedance or otherwise presented to the input circuit section as a result of including the impedance circuit section within the composite impedance portion.

15. The system of claim 14 , wherein one or more impedance circuit components of the impedance circuit are configured to remove the majority of the reactance of the inductive portion of the sense coil section.

16. 1. A method of operating an inductive position transducer system comprising at least a scale member, a first magnetic field generating coil section, and at least a first sensing coil section having a first coil terminal, a second coil terminal, and a coil impedance, comprising: providing a drive signal at an operating frequency to the first magnetic field generating coil section to generate a varying magnetic flux encompassing at least a portion of the first sensing coil section; receiving, in a sensing circuit section, from the first sensing coil section, a first sensing coil signal indicative of a relative position between the first sensing coil section and the scale member, the sensing circuit section comprising: an impedance circuit section connected to the first coil terminal and the second coil terminal, a first impedance circuit component coupled between the first impedance circuit node and a second impedance circuit node; and a second impedance circuit component, coupled between the first impedance circuit portion node and the second impedance circuit portion node; or a second impedance circuit component coupled between the first coil terminal and the first impedance circuit node; An impedance circuit unit comprising: an input circuit connected to the first impedance circuit node and the second impedance circuit node, the input circuit having an input impedance during operation and receiving an oscillation detection signal at the first impedance circuit node and the second impedance circuit node; A composite impedance portion comprising at least the impedance circuit portion and the first sensing coil portion has a composite impedance presented to the input circuit portion during operation.

17. 17. The method of claim 16, further comprising determining a relative position between the first sense coil portion and the scale member based at least in part on the received oscillating signal at the first impedance circuit portion node and at a second impedance circuit portion node.

18. A sensing circuit section included in an inductive position transducer system including a first sensing coil section having a first coil terminal, a second coil terminal, and a coil impedance, an impedance circuit section connected to the first coil terminal and the second coil terminal, a first impedance circuit component coupled between the first impedance circuit node and a second impedance circuit node; and a second impedance circuit component, coupled between the first impedance circuit portion node and the second impedance circuit portion node; or a second impedance circuit component coupled between the first coil terminal and the first impedance circuit node; An impedance circuit unit comprising: an input circuit connected to the first impedance circuit node and the second impedance circuit node, the input circuit having an input impedance during operation and configured to receive an oscillation sensing signal at the first impedance circuit node and the second impedance circuit node; A composite impedance portion comprising at least the impedance circuit portion and the first sensing coil portion has a composite impedance presented to the input circuit portion during operation.

19. The sensing circuitry of claim 18 , wherein the second impedance circuit component is coupled between the first impedance circuit node and the second impedance circuit node.

20. 20. The sensing circuitry of claim 19, wherein the impedance circuitry further comprises a third impedance circuitry component coupled between the first coil terminal and the first impedance circuitry node.

Images