Position sensor interface and method of operation thereof, position sensor system

Abstract

A position sensor interface and method of operation thereof, a position sensor system are disclosed. The position sensor interface includes a modulator configured to convert a plurality of digital feedback signals to a plurality of pulse density modulated (PDM) signals. The position sensor interface also includes a multiplier configured to multiply the plurality of PDM signals with a plurality of differential receiver signals, respectively. The multiplier includes a plurality of analog multiplexers configured to receive the plurality of differential receiver signals, each of the plurality of analog multiplexers having a differential multiplexer output coupled to a differential output of the multiplier. The multiplier also includes a control circuit configured to control each of the plurality of analog multiplexers based on the plurality of PDM signals.

Description

Technical Field

[0001] This disclosure relates in general to position sensors, and more particularly to high-speed inductive position sensors with tracking loops. Background Technology

[0002] Many applications requiring movement, such as automotive and robotic applications, need to measure angular position (e.g., pedal angle or arm angle). For such applications, inductive position sensors may be desirable because they provide accurate measurements while being resistant to harsh environmental conditions. For example, an inductive position sensor can be used to measure the angular position of a rotating element by sensing changes in the magnetic coupling between a stationary coil and a rotor coil that moves with the rotating element.

[0003] Improving the speed and / or resolution of these position sensors may be desirable, but may be limited by the corresponding increase in manufacturing costs. The inventors of the embodiments of this disclosure have recognized that techniques for improving the accuracy of magnetic position sensors typically come at the cost of measurement speed. The inventors of the embodiments of this disclosure have also recognized that techniques for improving the speed of magnetic position sensors typically come at the cost of accuracy. Embodiments of this disclosure address one or more of these challenges. Summary of the Invention

[0004] According to a first aspect, a position sensor interface is provided, the position sensor interface comprising: a modulator configured to convert a plurality of digital feedback signals into a plurality of pulse density modulated (PDM) signals; and a multiplier configured to multiply the plurality of PDM signals by a plurality of differential receiver signals, the multiplier comprising: a plurality of analog multiplexers configured to receive the plurality of differential receiver signals, each of the plurality of analog multiplexers having a differential multiplexer output coupled to a differential output of the multiplier; and a control circuit configured to control each of the plurality of analog multiplexers based on the plurality of PDM signals.

[0005] According to a second aspect, a position sensor system is provided, the position sensor system comprising: an excitation coil driven by an AC source; a rotor coil inductively coupled to the excitation coil; a plurality of receiver coils coupled and inductively coupled to the rotor coil in a Y configuration; and a position sensor interface configured to receive a plurality of differential receiver signals from the plurality of receiver coils, the position sensor interface comprising: a modulator configured to convert the plurality of digital feedback signals into a plurality of pulse density modulated signals. The PDM signals; and a multiplier configured to multiply the plurality of PDM signals by the plurality of differential receiver signals, the multiplier comprising: a plurality of analog multiplexers configured to receive the plurality of differential receiver signals, each of the plurality of analog multiplexers having a differential multiplexer output coupled to the differential output of the multiplier; and control circuitry configured to control each of the plurality of analog multiplexers based on the plurality of PDM signals.

[0006] According to a third aspect, a method for operating a position sensor interface is provided, the method comprising: receiving a plurality of differential receiver signals at a plurality of analog multiplexers; converting a plurality of digital feedback signals into a plurality of pulse density modulation (PDM) signals; and controlling the operating state of each of the plurality of analog multiplexers based on the plurality of PDM signals to multiply the plurality of differential receiver signals with the plurality of PDM signals. Attached Figure Description

[0007] A more complete understanding of this embodiment can be obtained by referring to the following description taken in conjunction with the accompanying drawings, in which similar reference numerals indicate similar features.

[0008] Figure 1 An angular position sensor according to an embodiment of the present disclosure is illustrated.

[0009] Figure 2A A schematic circuit model of an angular position sensor according to an embodiment of the present disclosure is illustrated.

[0010] Figure 2B A schematic circuit model of a three-phase receiver coil group according to an embodiment of the present disclosure is illustrated.

[0011] Figure 3 A schematic diagram of a position sensor system according to an embodiment of the present disclosure is illustrated.

[0012] Figure 4 The operating states of a simulated multiplexer according to an embodiment of this disclosure are illustrated.

[0013] Figure 5 The operating states of a multiplier according to an embodiment of this disclosure are illustrated.

[0014] Figure 6 A schematic diagram of a position sensor system according to an embodiment of the present disclosure is illustrated.

[0015] Figure 7 An example method for operating a position sensor interface according to an embodiment of this disclosure is illustrated. Detailed Implementation

[0016] Details of one or more embodiments are set forth in the following description and accompanying drawings. Other features will be apparent from the description, the drawings, and the claims. The disclosed embodiments should not be construed as or otherwise used to limit the scope of this disclosure, including the claims. Furthermore, those skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is intended to be an example of that embodiment and is not intended to imply that the scope of this disclosure, including the claims, is limited to that embodiment.

[0017] Various terms are used to refer to specific system components. Different companies may use different names to refer to a component, and this disclosure is not intended to distinguish between components with different names but the same form and function. In the following discussion and in the claims, the terms "comprising" and "including" are used in an open form, and therefore, these terms should be interpreted as meaning "including but not limited to". Furthermore, the terms "coupled" or "coupled" are intended to cover indirect or direct connections. Thus, if a first device is coupled to or coupled to a second device, the connection between the first device and the second device can be achieved through a direct connection or through an indirect connection via other devices and connectors.

[0018] Furthermore, although terms such as “first,” “second,” etc., may be used herein to describe various elements, these elements should not be limited by these terms. Terms such as “first” and “second” may be used only to distinguish one element from another. For example, a first element may be named a second element, and similarly, a second element may be named a first element, without departing from the scope of this disclosure. Moreover, the identification of a “first” element does not necessarily require the presence of a “second” element. As used herein, the term “and / or” includes any and all combinations of one or more of the associated entries listed.

[0019] Figure 1An angular position sensor 100 according to an embodiment of the present disclosure is illustrated. The angular position sensor 100 may include an excitation coil 110, an alternating current (AC) voltage source 112, a rotor coil 120, and a plurality of receiver coils, including a first receiver coil 130 and a second receiver coil 140.

[0020] Excitation coil 110 may be stationary and may be coupled to AC voltage source 112. AC voltage source 112 may be configured to generate an excitation signal at a certain frequency (e.g., radio frequency (RF)). In some embodiments, the excitation signal may have a frequency, for example, in the megahertz (MHz) range of the electromagnetic spectrum. Excitation coil 110 may be planar and may define a first plane. Current in excitation coil 110 may generate an excitation (magnetic) field transverse to the first plane. Excitation coil 110 has a substantially circular shape symmetrical about an axis of symmetry 105 located at the center of excitation coil 110 and transverse to the plane of the excitation coil. For example, excitation coil 110 may be a helical structure with multiple turns. The helical structure may form a loop (or ring), and other coils may be located inside or outside the loop (or ring), as shown. As directly described below, excitation coil 110 may be magnetically coupled to rotor coil 120.

[0021] The rotor coil 120 may be planar and may define a second plane. The second plane defined by the rotor coil 120 may be separated from the first plane defined by the excitation coil 110 by an air gap 121. Due to the symmetrical loop formation of the excitation coil 110, the inductive coupling between the excitation coil 110 and the rotor coil 120 may be independent of the rotor angle (θ). However, the inductive coupling between the excitation coil 110 and the rotor coil 120 may be a function of the air gap 121. For example, the inductive coupling from the exciter to the rotor decreases as the distance of the air gap 121 between the excitation coil 110 and the rotor coil 120 increases. Similarly, the inductive coupling from the exciter to the rotor increases as the distance of the air gap 121 between the excitation coil 110 and the rotor coil 120 decreases.

[0022] The rotor coil 120 may be planar and movable, and may rotate about an axis of symmetry 105 to a rotor angle 123 (θ), which intersects the plane of the rotor coil 120 at its center. The rotor coil 120 may form a repeating angle (θ)-dependent pattern. For example, the rotor coil 120 may form an angle (θ)-dependent pattern that has rotational symmetry. The pattern may include multiple lobes. For example, as... Figure 1 As shown, the rotor coil 120 may have four lobes regularly positioned around an axis of symmetry 105. Each lobe has a mechanical period 122 comprising a positive portion (i.e., positive lobe 124) and a negative portion (i.e., negative lobe 125). Figure 1The positive lobe 124 shown can be defined as the portion of the rotor coil 120 at a first radius from the axis of symmetry 105. Furthermore, as... Figure 1 The negative lobe 125 shown can be defined as the portion of the rotor coil 120 at a second radius from the axis of symmetry 105, where the first radius is larger than the second radius. In other words, the rotor coil 120 is rotationally symmetric about the axis of symmetry 105, where the order of rotational symmetry corresponds to the number of lobes (i.e., periods). For example, Figure 1 The embodiment of the rotor coil 120 shown can be described as having fourth-order rotational symmetry (quadruple symmetry). As described in more detail below, the fourth-order rotational symmetry of the rotor coil 120 (and the similar symmetry of the receiver coil) can produce an electrical receiver signal that is angle (θ) dependent, which repeats four times over a complete 360-degree mechanical rotation.

[0023] Rotor coil 120 can be configured to receive an excitation signal from excitation coil 110 via inductive coupling from the exciter to the rotor. A current can be induced in the magnetic field coupled from excitation coil 110 to flow in rotor coil 120. Furthermore, rotor coil 120 can generate a secondary field corresponding to the excitation signal. As directly described below, this secondary field can interact with multiple receiver coils.

[0024] Multiple receiver coils (such as a first receiver coil 130 and a second receiver coil 140) can be configured to receive the secondary field of the rotor coil 120 via inductive coupling between the rotor coil 120 and the receiver coils. Each of the multiple receiver coils may be planar. Furthermore, the multiple receiver coils may be placed in the same plane (the first plane) or approximately the same plane as the excitation coil 110. For example, the multiple receiver coils may occupy a plane parallel to the first plane containing the excitation coil 110 and within a range of ±1000 micrometers from the first plane. Therefore, the inductive coupling between the rotor coil 120 and the receiver coils (i.e., rotor-to-receiver inductive coupling) can be a function of the air gap 121. For example, the rotor-to-receiver inductive coupling decreases as the distance of the air gap 121 between the rotor coil 120 and the multiple receiver coils increases. Similarly, the rotor-to-receiver inductive coupling increases as the distance of the air gap 121 between the rotor coil 120 and the multiple receiver coils decreases.

[0025] The movement (i.e., rotation) of the plurality of receiver coils relative to the rotor coil 120 can be stationary. For example... Figure 1As shown, the plurality of receiver coils may include a first receiver coil 130 and a second receiver coil 140. The first receiver coil 130 may be formed with a first pattern substantially identical to the pattern of the rotor coil 120. Similarly, the second receiver coil 140 may be formed with a second pattern substantially identical to the pattern of the rotor coil 120. In other words, the first pattern of the first receiver coil 130 may be substantially identical to the second pattern of the second receiver coil 140. Figure 1 As shown, the first receiver coil 130 and the second receiver coil 140 have an angular offset relative to each other, which is a quarter mechanical period 122 of the rotational symmetry about the axis of symmetry 105. In other words, the plurality of receiver coils, including, for example, the first receiver coil 130 and the second receiver coil 140, can rotate in space relative to each other.

[0026] As the rotor coil 120 rotates about the axis of symmetry 105, the inductive coupling between the rotor coil 120 and the first receiver coil 130 may change. For example, at the angle where the patterns (e.g., the corresponding positive and negative lobes) are aligned, the inductive coupling between the rotor coil 120 and the first receiver coil 130 may be at its maximum. Conversely, at the angle where the negative lobe of the rotor coil 120 is aligned with the positive lobe of the first receiver coil 130, the inductive coupling between the rotor coil 120 and the first receiver coil 130 may be at its minimum.

[0027] As the rotor coil 120 rotates about the axis of symmetry 105, the inductive coupling between the rotor coil 120 and the second receiver coil 140 may change. For example, at the angle where the patterns (e.g., the corresponding positive and negative lobes) are aligned, the inductive coupling between the rotor coil 120 and the second receiver coil 140 may be at its maximum. Conversely, at the angle where the negative lobe of the rotor coil 120 is aligned with the positive lobe of the second receiver coil 140, the inductive coupling between the rotor coil 120 and the second receiver coil 140 may be at its minimum.

[0028] The first receiver coil 130 can generate a first received signal that varies sinusoidally according to the angle (θ) of the rotor coil 120. For Figure 1 The example shown is a specific implementation in which the first received signal can be repeated four times during one complete cycle of the rotor coil 120. For example, as Figure 1As shown, rotating the rotor within an angular range corresponding to a mechanical cycle 122 (e.g., 90 degrees) of rotational symmetry can correspond to one electrical cycle of the first received signal. In other words, the first received signal can have a spatial frequency corresponding to a rotational symmetry order (e.g., fourth order). Similarly, the second receiver coil 140 can generate a second received signal that varies sinusoidally and repeats four times during one complete revolution of the rotor coil 120. The first and second received signals can have the same frequency, but may be electrically phase-shifted relative to each other due to the angular offset between the first receiver coil 130 and the second receiver coil 140.

[0029] The electrical phase shift (e.g., a 90-degree electrical phase shift) between the first and second received signals can correspond to an angular offset (e.g., a 22.5-degree mechanical angular offset) between the respective receiver coils. The first and second received signals can be orthogonal, so the first received signal corresponds to the sine of the angle (i.e., SIN(θ)) and the second received signal corresponds to the cosine of the angle (i.e., COS(θ)). Therefore, the angle (θ) measurement can be calculated as the arctangent of the received signals (θ = tan⁻¹(sin(θ) / cos(θ))). In some embodiments, this arctangent calculation may be desirable because the common amplitude variations of the first and second received signals cancel each other out.

[0030] Figure 2A A schematic circuit model of an angular position sensor according to an embodiment of the present disclosure is illustrated. For example, Figure 2A The above references are illustrated. Figure 1 A schematic circuit model of the various parts of the described angular position sensor 100 is shown. The excitation coil 110 is modeled as an exciter inductance (Lx), the rotor coil 120 as a rotor inductance (Lt), and the receiver coil (e.g., which may be one of a first receiver coil 130 or a second receiver coil 140) is modeled as a receiver inductance (Lr). The excitation coil and rotor coil are inductively coupled via exciter-rotor mutual inductance (Mxt). The exciter coil and receiver coil are inductively coupled via exciter-receiver mutual inductance (Mxr), which is constant with angle. The rotor coil and receiver coil are inductively coupled via rotor-receiver mutual inductance (Mtr). Therefore, the receiver coil voltage (Vr) can be related to the excitation current (Ix) by the following equation:

[0031] In the above equation, the coil voltage (Vr) is a function of the air gap (z) and the angle (θ). In the first approximation, the rotor-receiver mutual inductance (M... trThe coil voltage (Vr) is the product of the first function of the air gap (M(z)) and the second function of the angle (M(θ)), where the second function is either a pure sine or cosine function. Therefore, the coil voltage (Vr) can be a sine function with angle (θ).

[0032] When the rotor coil completes one revolution, the sinusoidal coil voltage can go through multiple cycles. For Figure 1 In the example shown, the coil voltage has four electrical cycles for each mechanical turn. Furthermore, the coil voltage can vary depending on the air gap dependence. Therefore, it is not possible to determine the angle from a single coil voltage. Thus, a practical inductive sensor may include multiple receiver coils with the same air gap dependence. In such embodiments, the angle can be determined based on the ratio of signals from the multiple receiver coils, whereby the equal air gap dependencies of the different receiver coils cancel each other out. For example, as referenced above... Figure 1 As described, an inductive position sensor may include two receiver coils, including a first receiver coil 130 and a second receiver coil 140. In other embodiments, an inductive position sensor may include, for example, three receiver coils. For any such example, the plurality of receiver coils in a given embodiment may be shaped identically relative to each other (e.g., having the same number of lobes). The plurality of receiver coils may also be symmetrical about a common axis of rotation and planar on a common plane. The receiver coils may be evenly spaced and mechanically rotated relative to each other. For example, when implementing three receiver coils, each of the three receiver coils may be mechanically positioned relative to each other at ±3 / 4 of a mechanical cycle 122, thereby generating three electrical receiver signals ±120 degrees to each other to create a rotationally symmetrical and repeating 360-degree pattern.

[0033] Figure 2B A schematic circuit model of a three-phase receiver coil group 202 according to an embodiment of the present disclosure is illustrated. Figure 2B As shown, the 3-phase receiver coil group 202 may include three receiver coils. Each of these three receiver coils can be configured in accordance with the above description. Figure 1 and Figure 2A The receiver coil in the image is similarly inductively coupled to the rotor coil of the angular position sensor. Similarly, as described in the image... Figure 2B As shown, the three receiver coils can be coupled in a Y configuration (also known as a three-way configuration). Differential receiver signals such as Rec1, Rec2, and Rec3 can be provided by the three-phase receiver coil group 202. For example, the differential receiver signal Rec1 can represent the voltage (V) at node A. A ) and the voltage at node B (V B The difference between them. Furthermore, the differential receiver signal Rec2 can represent the voltage (V) at node B. B) and the voltage at node C (V C The difference between them. Furthermore, the differential receiver signal Rec3 can represent the voltage (V) at node C. C ) and the voltage at node A (V A The difference between Rec1, Rec2, and Rec3. As described by Kirchhoff's voltage law, the sum of Rec1, Rec2, and Rec3 is zero volts.

[0034] Figure 3 A schematic diagram of a position sensor system 300 according to an embodiment of the present disclosure is illustrated. The position sensor system 300 can be implemented in any suitable manner according to the operation described in this disclosure. Figure 3 As shown, the position sensor system 300 may include an angular position sensor 301. The angular position sensor 301 may include an AC source 302, an excitation coil 304, a rotor coil 306, and a three-phase receiver coil group 202. The excitation coil 304 may be configured to be driven by the AC source 302. The rotor coil 306 may be inductively coupled to the excitation coil 304. Furthermore, the three-phase receiver coil group 202 may be inductively coupled to the rotor coil 306.

[0035] In some embodiments, the excitation coil 304 may be differentially driven at a certain frequency by the AC source 302. As described in more detail below, the sampling frequency of the position sensor interface 310 may be synchronized with the frequency of the AC source 302. Therefore, the AC source 302 can drive the excitation coil 304 at any suitable frequency to sample the angular position (θ) of the rotor coil 306. In some embodiments, for example, the AC source 302 may drive the excitation coil 304 at a frequency of 4 MHz. In other embodiments, the AC source 302 may drive the excitation coil 304 at frequencies higher or lower than 4 MHz. (Refer to above) Figure 2B As described, and as Figure 3 As shown, the three-phase receiver coil group 202 may include multiple receiver coils coupled in a Y configuration and inductively coupled to the rotor coil 306. Therefore, the three-phase receiver coil group 202 can provide three differential receiver signals, in the form of: representing V A With V B Rec1, representing the differential voltage between, indicates V B With V C Rec2 of the differential voltage between and V C With V A The differential voltage Rec3 between them.

[0036] The position sensor system 300 may also include a position sensor interface 310. The position sensor interface 310 may be implemented in any suitable manner according to the operation described in this disclosure. Figure 3As shown, the position sensor interface 310 may include a multiplier 320, a low-pass filter 330, a processing circuit 340, a feedback circuit 350, and a modulator 360. At a high level, the components of the position sensor interface 310 can generate a digital angle value (…). The tracking loop, whose digital angle value tracks the rotor angle ( For example, the position sensor interface 310 can receive multiple differential receiver signals (Rec1, Rec2, and Rec3) from the angular position sensor 301. These multiple differential receiver signals (Rec1, Rec2, and Rec3) can be processed to determine a digital angle value. ).like Figure 3 As shown, the position sensor interface 310 can also receive a fourth input (Rec4) corresponding to the AC source 302. The fourth input (Rec4) can be used to compensate for offsets in the tracking loop that might otherwise occur due to (albeit small) inductive coupling between the excitation coil 304 and the three-phase receiver coil group 202.

[0037] Before describing an example of the physical circuitry used for the position sensor interface 310, the mathematical principles behind the operation of the position sensor interface 310 are described. First, the signals from multiple differential receivers can be represented by equations 1 through 4 below.

[0038]

[0039] In equations 1 to 4 above, Here, A is the rotor angle, A is the coupling amplitude between the rotor coil and multiple receiver coils, and B1, B2, and B3 are constant offsets proportional to the amplitude of the excitation signal and independent of the rotor position. Furthermore, B4 is a constant coefficient proportional to the excitation signal and independent of the rotor position. As described in more detail below, the tracking loop can generate multiple feedback signals (such as digital feedback signal 355) that can be represented according to Equations 5 through 8 below.

[0040]

[0041] The sum of the products of multiple receiver signals multiplied by the corresponding feedback signals can be expressed according to Equation 9 below.

[0042]

[0043] According to Equation 9, if the numerical angle value ( ) equals the rotor angle ( If the sum of the products of multiple receiver signals and the corresponding products of multiple feedback signals is zero, then in order to detect the rotor angle ( The tracking loop can continuously determine and update the digital angle value. The objective is to make the sum of the products of multiple receiver signals multiplied by the corresponding products of multiple feedback signals zero.

[0044] Return to reference Figure 3 The feedback circuit 350 can be configured to generate multiple digital feedback signals 355 based on the digital error signal 349 from the processing circuit 340. Specifically, the feedback circuit 350 can determine and update the digital angle value ( This is to make the target value of the digital error signal 349 zero, which can represent the product of multiple receiver signals multiplied by corresponding multiple feedback signals, as described above in mathematical equations 1 to 9. The multiple digital feedback signals 355 may include at least those based on digital angle values ​​( The first cosine signal, the second cosine signal, and the third cosine signal. In some embodiments, the plurality of digital feedback signals 355 may further include at least those based on digital angle values ​​( The fourth cosine signal of ). For example, multiple digital feedback signals 355 may include digital representations of the feedback signals FB1, FB2, FB3 and FB4 described above in Equations 5 to 8.

[0045] like Figure 3 As shown, modulator 360 can be coupled to receive multiple digital feedback signals 355 from feedback circuitry 350. Modulator 360 can be configured to convert the multiple digital feedback signals 355 into multiple pulse density modulated (PDM) signals 365. In some embodiments, modulator 360 may be a Σ-Δ modulator. Figure 3 As shown, modulator 360 can be synchronized with the frequency of the excitation signal provided by AC source 302. For example, in an embodiment where AC source 302 provides a 4MHz excitation signal, modulator 360 can output multiple PDM signals 365 at a frequency of 4MHz. The corresponding pulse densities of the multiple PDM signals 365 can correspond to the digital values ​​of the corresponding digital feedback signals 355. Therefore, the multiple PDM signals 365 can include pulse density modulated representations of the feedback signals FB1, FB2, FB3, and FB4 described above in Equations 5 to 8. Although modulator 360 in Figure 3 While illustrated as a single circuit block, modulator 360 may include multiple components. For example, modulator 360 may include multiple modulators (e.g., Σ-Δ modulators) or be implemented by multiple modulators, each modulator being configured to modulate a corresponding digital feedback signal in a plurality of digital feedback signals 355 corresponding to FB1, FB2, FB3 and FB4 described above in Equations 5 to 8.

[0046] Despite Figure 3The circuit is illustrated as a separate circuit block, but the feedback circuit 350, modulator 360, and / or control circuit 321 can be implemented in the same circuit block. For example, the feedback circuit 350, modulator 360, and / or control circuit 321 can be implemented together, in whole or in part, in the same digital circuit block.

[0047] Multiplier 320 may be configured to multiply a plurality of PDM signals 365 with a plurality of differential receiver signals (Rec1, Rec2, Rec3, Rec4), respectively. Multiplier 320 may be implemented in any suitable manner according to the operation described in this disclosure. In some embodiments, multiplier 320 may be configured to multiply Rec1 with a first PDM signal representing FB1, Rec2 with a second PDM signal representing FB2, Rec3 with a third PDM signal representing FB3, and Rec4 with a fourth PDM signal representing FB4. Multiplier 320 may include a plurality of analog multiplexers 322a to 322d and control circuitry 321 configured to control each of the plurality of analog multiplexers 322a to 322d based on the plurality of PDM signals 365. As described in detail below, the control circuit 321 and the analog multiplexers 322a to 322d can work together to multiply multiple PDM signals 365 with multiple differential receiver signals (Rec1, Rec2, Rec3, Rec4).

[0048] Multiple analog multiplexers 322a to 322d can be configured to receive multiple differential receiver signals. In some embodiments, the multiple differential receiver signals may include at least a first sine wave (Rec1), a second sine wave (Rec2), and a third sine wave (Rec3) based on the rotor angle of the angular position sensor 301. The multiple differential receiver signals may also include a fourth signal based at least on the excitation amplitude of the angular position sensor 301. For example, as described above, referring to equations 1 to 4, Rec1, Rec2, and Rec3 may be at least based on the rotor angle of the angular position sensor 301 (Rec1, Rec2, and Rec3). The first, second, and third sinusoidal signals are given. Additionally, Rec4 can be a fourth signal based on a constant coefficient (B4) proportional to the excitation signal. Figure 3 As shown, analog multiplexer 322a can receive a first differential receiver signal (Rec1), analog multiplexer 322b can receive a second differential receiver signal (Rec2), analog multiplexer 322c can receive a third differential receiver signal (Rec3), and analog multiplexer 322d can receive a fourth differential receiver signal (Rec4).

[0049] Analog multiplexers 322a to 322d may each include multiple switches or transmission gates, which can be controlled by control circuitry 321 to provide one of three analog multiplexer operations. Specifically, based on multiple PDM signals 365, each analog multiplexer can be configured to provide one of the following: non-inverting rectification of a corresponding differential receiver signal among multiple differential receiver signals, inverting rectification of the corresponding differential receiver signal among multiple differential receiver signals, or high-impedance output.

[0050] Figure 4 The operating states of analog multiplexers 322a to 322d according to embodiments of this disclosure are illustrated. (Refer to the above text.) Figure 3 As described, modulator 360 can be synchronized with the frequency of the excitation signal from AC source 302. In some embodiments, the excitation signal from AC source 302 may have a frequency of, for example, 4 MHz. Therefore, the input sine wave of each of analog multiplexers 322a to 322d may have a period of 250 ns. Figure 4 As shown, non-inverting rectification of wave signals (such as Rec1, Rec2, Rec3, or Rec4) can rectify positive signals and output them. Inverting rectification of wave signals (such as Rec1, Rec2, Rec3, or Rec4) can rectify negative signals and output them. High-impedance output can be achieved by simply shutting off all internal switches or transmission gates of the analog multiplexer, making the output of the analog multiplexer high-impedance.

[0051] Return to reference Figure 3 Each of the analog multiplexers 322a to 322d may have a differential multiplexer output coupled to the differential output 325 of the multiplier 320. At any given time, only one of the analog multiplexers 322a to 322d can provide either inverting or non-inverting rectification, while the others can be placed in a high-impedance state. Therefore, only one of the analog multiplexers 322a to 322d can deliver a signal to the differential output 325 of the multiplier 320 at any given time. See below for reference. Figure 5 The description controls analog multiplexers 322a to 322d to perform multiplication of multiple PDM signals 365 with multiple differential receiver signals Rec1, Rec2, Rec3 and Rec4.

[0052] Figure 5 The operating states of multiplier 320 according to an embodiment of the present disclosure are illustrated. As described above, the plurality of PDM signals 365 may include pulse density modulation representations of the feedback signals FB1, FB2, FB3, and FB4 described above in Equations 5 to 8. The PDM signals corresponding to FB1, FB2, and FB3 are in Figure 5 These are represented as PDM1, PDM2, and PDM3, respectively, where "0" represents logic 0 and "1" represents logic 1. For example... Figure 5 As shown, PDM1, PDM2 and PDM3 have eight possible combinations, including: 0-0-0, 0-0-1, 0-1-0, 0-1-1, 1-0-0, 1-0-1, 1-1-0 and 1-1-1.

[0053] exist Figure 5 Moving right from the center, the mathematical products of Rec1*PDM1, Rec2*PDM2, and Rec3*PDM3 are listed. For example, when PDM1 is logic 0, the product of Rec1*PDM1 equals –A sin( ) – B1. Furthermore, when PDM1 is logic 1, the product of Rec1 and PDM1 equals A sin( ) + B1. Furthermore, when PDM2 is logic 0, the product of Rec2*PDM2 equals –A sin( +120) – B2. Furthermore, when PDM2 is logic 1, the product of Rec2*PDM2 equals A sin( +120) + B2. Furthermore, when PDM3 is logic 0, the product of Rec3*PDM3 equals –A sin( +240) – B3. Furthermore, when PDM3 is logic 1, the product of Rec3 and PDM3 equals A sin( +240) + B3.

[0054] exist Figure 5 Moving further to the right, we consider the sum of the products of eight possible combinations of PDM1, PDM2, and PDM3. When PDM1, PDM2, and PDM3 are 0-0-0, the sum of the products is zero. Similarly, when PDM1, PDM2, and PDM3 are 1-1-1, the sum of the products is also zero. The zero sum when PDM1, PDM2, and PDM3 are each in the same logic state (0-0-0 or 1-1-1) is due to Kirchhoff's voltage law, as described above with reference to Figure 2, which states that the sum of Rec1 + Rec2 + Rec3 must be equal to zero. Given that the sum is zero during these conditions of Rec1*PDM1, Rec2*PDM2, and Rec3*PDM3, the analog multiplexers 322a to 322c corresponding to Rec1, Rec2, and Rec3 can all be placed in a high-impedance state (e.g., Figure 5(As indicated by "HiZ" in the original text). Furthermore, during these conditions, depending on the state of the fourth PDM signal corresponding to FB4, the analog multiplexer 322d can be placed in a non-inverting rectified state (as indicated by "+1") or an inverting rectified state (as indicated by "-1"), as described above with reference to Equation 8. In other words, during the logic state where the sum of Rec1*PDM1, Rec2*PDM2, and Rec3*PDM3 equals zero due to Kirchhoff's voltage law, the analog multiplexers 322a to 322c corresponding to Rec1, Rec2, and Rec3 can be placed in a high-impedance state to block Rec1, Rec2, and Rec3, and Rec4 can alternatively be passed (using non-inverting or inverting rectification) to compensate for the offset described above with reference to Equations 4 and 8.

[0055] like Figure 5 As further shown, when PDM1, PDM2, and PDM3 are not all of the same logic value, the sum of their products (the sum of Rec1*PDM1, Rec2*PDM2, and Rec3*PDM3) can be equal to a multiple of one of these three corresponding products. Therefore, one of the analog multiplexers 322a to 322c can be placed in either a non-inverting or inverting rectification state to pass the signal to the differential output 325 of the multiplier 320, while the others of the analog multiplexers 322a to 322d are placed in a high-impedance state.

[0056] For example, when PDM1, PDM2, and PDM3 are 0-0-1 or 1-1-0, the sum of the corresponding products (the sum of Rec1*PDM1, Rec2*PDM2, and Rec3*PDM3) can be a multiple of 2x the sum of Rec3*PDM3. Therefore, during these conditions (0-0-1 or 1-1-0), the analog multiplexers 322a, 322b, and 322d corresponding to Rec1, Rec2, and Rec4 can be placed in a high-impedance state (HiZ). Simultaneously, the analog multiplexer 322c corresponding to Rec3 is placed in a non-inverting rectified state (+1) during the 0-0-1 condition, or in an inverting rectified state (-1) during the 1-1-0 condition, to pass the signal to the differential output 325 of the multiplier 320.

[0057] Similarly, Figure 5As shown, when PDM1, PDM2, and PDM3 are 0-1-0 or 1-0-1, the sum of the corresponding products (the sum of Rec1*PDM1, Rec2*PDM2, and Rec3*PDM3) can be a multiple of 2x the sum of Rec2*PDM2. Therefore, during these conditions (0-1-0 or 1-0-1), the analog multiplexers 322a, 322c, and 322d corresponding to Rec1, Rec3, and Rec4 can be placed in a high-impedance state (HiZ). Simultaneously, the analog multiplexer 322b corresponding to Rec2 is placed in a non-inverting rectified state (+1) during the 0-1-0 condition, or in an inverting rectified state (-1) during the 1-0-1 condition, to pass the signal to the differential output 325 of the multiplier 320.

[0058] Furthermore, when PDM1, PDM2, and PDM3 are 0-1-1 or 1-0-0, the sum of the corresponding products (the sum of Rec1*PDM1, Rec2*PDM2, and Rec3*PDM3) can be a multiple of 2x the sum of Rec1*PDM1. Therefore, during these conditions (0-1-1 or 1-0-0), the analog multiplexers 322b, 322c, and 322d corresponding to Rec2, Rec3, and Rec4 can be placed in a high-impedance state (HiZ). Simultaneously, the analog multiplexer 322a corresponding to Rec1 is placed in a non-inverting rectified state (+1) during the 1-0-0 condition, or in an inverting rectified state (-1) during the 0-1-1 condition, to pass the signal to the differential output 325 of the multiplier 320.

[0059] Based on the operations described above, multiplier 320 and multiple analog multiplexers 322a to 322d can efficiently multiply Rec1, Rec2, Rec3, and Rec4 by multiple PDM signals 365 representing the feedback signals FB1, FB2, FB3, and FB4 described in reference equations 5 to 8 above, and can efficiently sum the corresponding products. By using analog multiplexers 322a to 322d, multiplication and summation can be performed without using different amplifiers in the corresponding paths of Rec1, Rec2, Rec3, and Rec4. Therefore, errors caused by mismatch between such different amplifiers corresponding to Rec1, Rec2, Rec3, and Rec4 can be avoided.

[0060] Return to reference Figure 3The position sensor interface 310 may include a low-pass filter 330 coupled to filter the differential output 325 of the multiplier 320. The low-pass filter 330 may be configured to filter out high-frequency components in the rectified signal passed to the differential output 325 of the multiplier 320. For example, as described above, the modulator 360 may be configured to modulate multiple digital feedback signals 355 at the same frequency as the excitation signal provided by the AC source 302. In an embodiment where the excitation signal and modulator 360 have a frequency of 4 MHz, the low-pass filter 330 may be configured to filter out resulting frequency components, such as 8 MHz and above, observed at the differential output 325 of the multiplier 320.

[0061] like Figure 3 As shown, processing circuitry 340 may be coupled to low-pass filter 330 to receive filter output 335. Processing circuitry may be configured to output a digital error signal 349 based on filter output 335. Processing circuitry 340 may be implemented in any suitable manner according to the operation described in this disclosure. Processing circuitry 340 may amplify the output of low-pass filter 330, integrate the amplified output, and convert the signal from the analog domain to the digital domain. In some embodiments, processing circuitry 340 may include transconductance amplifier 342, integrator 344, and analog-to-digital converter (ADC) 348. Transconductance amplifier 342 may be configured to amplify filter output 335. Integrator 344 may be configured to integrate the output of transconductance amplifier 342. For example, integrator 344 may include amplifier 345 having a differential input coupled to the differential output of transconductance amplifier 342. Furthermore, integrator 344 may include a first capacitor 346 coupled from a first differential input to a first differential output of amplifier 345, and a second capacitor 347 coupled from a second differential input to a second differential output of amplifier 345. Analog-to-digital converter (ADC) 348 may be configured to receive the integrator output from integrator 344 and generate a digital error signal 349. As described above, feedback circuit 350 may receive the digital error signal 349 and may determine and update the digital angle value ( ), so that the target value of the digital error signal 349 is zero, which, according to Equation 9 above, will make the digital angle value ( ) and rotor angle ( (and therefore track the rotor angle).

[0062] Because the tracking loop continuously updates the digital angle value representing the rotor's angular position ( Therefore, the rotor speed can also be derived, for example, from the digital error signal 349 output by the processing circuit 340. Since the integral of speed is position, the pre-integral input to the feedback circuit 350 (which can digitally integrate the digital error signal 349) can also represent speed. Therefore, although in Figure 3 Not specifically shown, but the digital error signal 349 can also be provided as speed information to a more advanced system in which the position sensor system 300 is incorporated.

[0063] although Figure 3 An embodiment of processing circuitry 340 is illustrated, wherein transconductance amplifier 342, integrator 344, and ADC 348 are coupled in successive stages of the signal path; however, the components of processing circuitry 340 can be arranged in any suitable manner. For example, in some embodiments, an ADC such as ADC 348 may be placed directly at the output of low-pass filter 330 or at the output of transconductance amplifier 342. In such embodiments, further amplification and / or integration can then be performed in the digital domain after the ADC to generate a digital error signal 349. Furthermore, in such embodiments, low-pass filter 330 may optionally be omitted, and filtering can be implemented in the digital domain by a digital filter downstream of the ADC.

[0064] Figure 6 A schematic diagram of a position sensor system 600 according to an embodiment of the present disclosure is illustrated. The position sensor system 600 can be implemented in any suitable manner according to the operation described in this disclosure. Figure 6 As shown, the position sensor system 600 may include an angular position sensor 301. The position sensor system 600 may also include a position sensor interface 610. Similar to the reference above... Figure 3 The described position sensor interface 310, position sensor interface 610 may include a tracking loop having a multiplier 320, a low-pass filter 330, processing circuitry 340, feedback circuitry 350, and modulator 360. The angular position sensor 301 and the tracking loop formed by the multiplier 320, low-pass filter 330, processing circuitry 340, feedback circuitry 350, and modulator 360 can be configured as described above. Figure 3 Operate in the same way as described.

[0065] like Figure 6As shown, the position sensor interface 610 may also include an amplitude detection path having a second modulator 660, a second multiplier 620, a second low-pass filter 630, and a second processing circuitry 640. As described in more detail below, the amplitude detection path including the second modulator 660, the second multiplier 620, the second low-pass filter 630, and the second processing circuitry 640 can operate in a similar manner to the tracking loop, but can output amplitude values ​​indicating the amplitudes of the various differential receiver signals Rec1, Rec2, and Rec3. Furthermore, these amplitude values ​​can be used, for example, to set the gain of the transconductance amplifier 342 (and the second transconductance amplifier 642), and / or to detect rotor faults. For example, a significant drop in the amplitude value may indicate rotor loss or other damage.

[0066] like Figure 6 As shown, in addition to generating multiple digital feedback signals 355 based on the digital error signal 349, the feedback circuit 350 can also be configured to generate a second plurality of feedback signals 655 based on the digital error signal 349. The second plurality of feedback signals 655 may include at least those based on digital angle values ​​(…). The feedback circuit 350 continuously updates the digital angle value using a first, second, third, and fourth feedback sinusoidal signal to track the rotor angle. The second set of multiple feedback signals 655 can be represented by the following equations 10 to 13.

[0067]

[0068] The second plurality of feedback signals 655 can be provided to the second modulator 660 by the feedback circuit 350. The second modulator 660 can be configured to convert the second plurality of feedback signals 655 from the feedback circuit 350 into a second plurality of pulse density modulation (PDM) signals 665. The second modulator 660 can operate in a manner similar to that of the modulator 360 described above. For example, the second modulator 660 can be a Σ-Δ modulator. Figure 6 As shown, the second modulator 660 can be synchronized with the frequency of the excitation signal provided by the AC source 302. For example, in an embodiment where the AC source 302 provides a 4MHz excitation signal, the second modulator 660 can output a second plurality of PDM signals 665 at a frequency of 4MHz. The corresponding pulse densities of the second plurality of PDM signals 665 can correspond to the digital values ​​of the second plurality of feedback signals 655. Therefore, the second plurality of PDM signals 665 can include pulse density modulated representations of the feedback signals FB21, FB22, FB23, and FB24 described above in Equations 10 to 13. Although the second modulator 660 in Figure 6While illustrated as a single circuit block, the second modulator 660 may include multiple components. For example, the second modulator 660 may include multiple modulators (e.g., Σ-Δ modulators) or be implemented by multiple modulators, each configured to modulate a corresponding feedback signal in the second plurality of feedback signals 655.

[0069] like Figure 6 As shown, the second multiplier 620 can be configured to receive a second plurality of PDM signals 665 from the second modulator 660. In some embodiments, the second multiplier 620 can be configured to multiply the second plurality of PDM signals 665 by a plurality of differential receiver signals (Rec1, Rec2, Rec3, Rec4), respectively. For example, the second multiplier 620 can be implemented in the same manner and can represent a second instance of multiplier 320, but the plurality of differential receiver signals (Rec1, Rec2, Rec3, Rec4) can be multiplied by the second plurality of PDM signals 665 instead of the first plurality of PDM signals 365. Therefore, the second multiplier 620 may include a second plurality of analog multiplexers configured to receive a plurality of differential receiver signals, each of the second plurality of analog multiplexers having a differential multiplexer output coupled to the differential output of the second multiplier. The second multiplier 620 may further include a second control circuit configured to control each of the second plurality of analog multiplexers based on the second plurality of PDM signals 665. The second control circuitry of the second plurality of analog multiplexers and the second multiplier 620 can be referenced. Figures 3 to 5 The multiple analog multiplexers 322a to 322d and the control circuit 321 operate in a similar manner to those described above, so as to multiply the second plurality of PDM signals 665 with the plurality of differential receiver signals (Rec1, Rec2, Rec3, Rec4) respectively.

[0070] Instead of multiplying with multiple PDM signals 365 representing the cosine signals in equations 5 to 8, the output of the second multiplier 620 provides a signal whose amplitude depends on the multiple receiver signals (Rec1, Rec2, Rec3, Rec4) by multiplying multiple receiver signals (Rec1, Rec2, Rec3, Rec4) by multiple receiver signals (Rec1, Rec2, Rec3, Rec4). Figure 6 As shown, the second low-pass filter 630 can be coupled to filter the differential output of the second multiplier 620. Furthermore, the second processing circuit 640 can be configured to output the amplitude value AMPLITUDE based on the filtered output of the second multiplier 620.

[0071] The second processing circuit 640 can be implemented in any suitable manner according to the operation described in this disclosure. The second processing circuit 640 can amplify the output of the second low-pass filter 630 and convert the signal from the analog domain to the digital domain. In some embodiments, the second processing circuit 640 may include a second transconductance amplifier 642, a gain stage 644, and a second analog-to-digital converter (ADC) 648. The second transconductance amplifier 642 may be configured to amplify the output of the second low-pass filter 630. The gain stage 644 may be configured to amplify the output of the second transconductance amplifier 642. For example, the gain stage 644 may include a second amplifier 645 having a differential input coupled to the differential output of the second transconductance amplifier 642. Furthermore, the gain stage 644 may include a first resistor 646 coupled from the first differential input to the first differential output of the second amplifier 645, and a second resistor 647 coupled from the second differential input to the second differential output of the second amplifier 645. The second ADC 648 may be configured to receive the gain stage output from the gain stage 644 and generate an amplitude value AMPLITUDE. Furthermore, this amplitude value can be used, for example, to set the gain of transconductance amplifier 342 (and the second transconductance amplifier 642), and / or to detect rotor faults. For example, a significant drop in the amplitude value could indicate that the rotor is missing or otherwise damaged.

[0072] although Figure 6 An embodiment of the second processing circuit 640 is illustrated, in which the second transconductance amplifier 642, the gain stage 644, and the second ADC 648 are coupled in successive stages of the signal path; however, the components of the second processing circuit 640 can be arranged in any suitable manner. For example, in some embodiments, the ADC, such as the second ADC 648, may be placed directly at the output of the second low-pass filter 630 or at the output of the second transconductance amplifier 642. In such embodiments, further amplification or filtering can then be performed in the digital domain after the ADC to generate the amplitude value AMPLITUDE.

[0073] Figure 7 An example method 700 for operating a position sensor interface according to an embodiment of the present disclosure is illustrated. Method 700 can be performed by any suitable mechanism, such as position sensor interface 310, position sensor interface 610, and / or any suitable combination of the components included therein. In some embodiments, method 700 can be used in a manner more... Figure 7 It can be performed in fewer or more steps as shown.

[0074] Step 702 may include receiving multiple differential receiver signals at multiple analog multiplexers. For example, as referenced above. Figure 3As described, multiple analog multiplexers 322a to 322d within the multiplier 320 of the position sensor interface 310 can receive multiple differential receiver signals (Rec1, Rec2, Rec3) from the angular position sensor 301. The position sensor interface 310 can also receive Rec4 corresponding to the AC source 302. Figure 3 As shown, analog multiplexer 322a can receive a first differential receiver signal (Rec1), analog multiplexer 322b can receive a second differential receiver signal (Rec2), analog multiplexer 322c can receive a third differential receiver signal (Rec3), and analog multiplexer 322d can receive a fourth differential receiver signal (Rec4).

[0075] Step 704 may include: converting multiple digital feedback signals into multiple pulse density modulation (PDM) signals. For example, as referenced above. Figure 3 As described, modulator 360 may be coupled to receive multiple digital feedback signals 355 from feedback circuitry 350. Modulator 360 may be configured to convert the multiple digital feedback signals 355 into multiple pulse density modulated (PDM) signals 365. In some embodiments, modulator 360 may be a Σ-Δ modulator. Figure 3 As shown, modulator 360 can be synchronized with the frequency of the excitation signal provided by AC source 302. For example, in an embodiment where AC source 302 provides a 4MHz excitation signal, modulator 360 can output multiple PDM signals 365 at a frequency of 4MHz. The corresponding pulse densities of the multiple PDM signals 365 can correspond to the digital values ​​of the corresponding digital feedback signals 355. Therefore, the multiple PDM signals 365 can include pulse density modulated representations of the feedback signals FB1, FB2, FB3, and FB4 described above in Equations 5 to 8.

[0076] Step 706 may include: controlling the operating state of each of the multiple analog multiplexers based on multiple PDM signals to multiply the multiple differential receiver signals with the multiple PDM signals. For example, as referenced above. Figure 3 , Figure 4 and Figure 5 As described, the control circuit 321 can control the operating state (high impedance operation state, inverting rectification state, or non-inverting rectification state) of each of the multiple analog multiplexers 322a to 322d based on multiple PDM signals 365, so as to effectively multiply multiple differential receiver signals (Rec1, Rec2, Rec3, and Rec4) with multiple PDM signals 365, which respectively include the pulse density modulated representations of the feedback signals FB1, FB2, FB3, and FB4 described above in Equations 5 to 8.

[0077] Step 708 may include filtering the output of the differential multiplier. For example, as referenced above. Figure 3 As described, the low-pass filter 330 can filter the differential output terminal 325 of the multiplier 320.

[0078] Step 710 may include: generating a digital error signal based on the filter output. For example, as referenced above. Figure 3 As described, processing circuitry 340 may be coupled to low-pass filter 330 to receive filter output 335. Processing circuitry 340 may be configured to output a digital error signal 349 based on filter output 335. In some embodiments, processing circuitry 340 may include transconductance amplifier 342, integrator 344, and analog-to-digital converter (ADC) 348. Thus, processing circuitry 340 may amplify the output of low-pass filter 330, integrate the amplified output, and convert the signal from the analog domain to the digital domain to generate digital error signal 349.

[0079] Step 712 may include: generating multiple digital feedback signals based on the digital error signal. For example, as referenced above. Figure 3 As described, the feedback circuit 350 can be configured to generate a plurality of digital feedback signals 355 based on the digital error signal 349 from the processing circuit 340. The plurality of digital feedback signals 355 may include digital representations of the feedback signals FB1, FB2, FB3 and FB4 described above in Equations 5 to 8.

[0080] As referenced above Figure 3 The components of the position sensor interface 310, as described, including a multiplier 320, a low-pass filter 330, a processing circuit 340, a feedback circuit 350, and a modulator 360, can be used as a tracking loop, whereby the feedback circuit 350 continuously updates the digital angle value. ), so that the target value of the digital error signal 349 is zero, thereby providing a digital angle value ( This digital angle value tracks the rotor angle ( Therefore, the steps of method 700 can be repeated continuously. Furthermore, the steps of method 700 can be considered as the tracking loop continuously updates the digital angle value (…). They are executed in parallel and continuously.

[0081] Although examples have been described above, other modifications and variations can be made from this disclosure without departing from the spirit and scope of these examples. The description of the various embodiments above exemplifies the principles of the invention. Based on the above disclosure, many variations and modifications will become apparent to those skilled in the art. The following claims are intended to encompass all such variations and modifications.

Claims

1. A position sensor interface, the position sensor interface comprising: A modulator configured to convert multiple digital feedback signals into multiple pulse density modulated (PDM) signals; and A multiplier configured to multiply the plurality of PDM signals by a plurality of differential receiver signals, the multiplier comprising: A plurality of analog multiplexers are configured to receive signals from a plurality of differential receivers, each of the plurality of analog multiplexers having a differential multiplexer output coupled to the differential output of the multiplier. and A control circuit configured to control each of the plurality of analog multiplexers based on the plurality of PDM signals.

2. The position sensor interface of claim 1, wherein, based on the plurality of PDM signals, each of the plurality of analog multiplexers is configured to provide one of the following: non-inverting rectification of a corresponding differential receiver signal among the plurality of differential receiver signals, inverting rectification of the corresponding differential receiver signal among the plurality of differential receiver signals, or high-impedance output.

3. The position sensor interface according to claim 1, wherein the modulator is a Σ-Δ modulator.

4. The position sensor interface according to claim 1, further comprising: A low-pass filter, which is coupled to filter the differential output of the multiplier; A processing circuit configured to output a digital error signal based on a filter output; and A feedback circuit configured to generate the plurality of digital feedback signals based on the digital error signal.

5. The position sensor interface according to claim 4, wherein the processing circuit comprises: A transconductance amplifier configured to amplify the filter output; An integrator configured to integrate the output of the transconductance amplifier; and An analog-to-digital converter (ADC) is configured to receive the output of an integrator and generate the digital error signal.

6. The position sensor interface according to claim 1, wherein: The plurality of digital feedback signals include at least a first cosine signal, a second cosine signal, and a third cosine signal based on digital angle values; and The plurality of differential receiver signals include at least a first sine signal, a second sine signal, and a third sine signal based on the rotor angle of the position sensor.

7. The position sensor interface according to claim 6, wherein: The plurality of differential receiver signals also include a fourth signal based at least on the excitation amplitude of the position sensor; and The plurality of digital feedback signals also include at least a fourth cosine signal based on the digital angle value.

8. The position sensor interface according to claim 4, further comprising an amplitude detection path, the amplitude detection path comprising: The system includes a second modulator, a second multiplier, a second low-pass filter, and a second processing circuit. The second modulator is configured to convert a second plurality of feedback signals from the feedback circuit into a second plurality of pulse density modulated (PDM) signals; The second multiplier is configured to multiply the second plurality of PDM signals by the plurality of differential receiver signals, respectively, and the second multiplier includes: A second plurality of analog multiplexers, configured to receive the plurality of differential receiver signals, each of the second plurality of analog multiplexers having a differential multiplexer output coupled to the differential output of the second multiplier; and A second control circuit is configured to control each of the second plurality of analog multiplexers based on the second plurality of PDM signals. The second low-pass filter is coupled to filter the differential output of the second multiplier; and The second processing circuit is configured to output an amplitude value based on the filtered output of the second multiplier.

9. The position sensor interface according to claim 8, wherein the second processing circuit comprises: A second transconductance amplifier is configured to amplify the output of the second low-pass filter; A gain stage, configured to amplify the output of the second transconductance amplifier; and The second ADC is configured to receive the output of the gain stage and generate the amplitude value.

10. The position sensor interface according to claim 8, wherein: The plurality of differential receiver signals include at least a first sine signal, a second sine signal, and a third sine signal based on the rotor angle of the position sensor; and The second plurality of feedback signals include at least a first feedback sine signal, a second feedback sine signal, a third feedback sine signal, and a fourth feedback sine signal based on digital angle values.

11. A position sensor system, the position sensor system comprising: An excitation coil, which is driven by an AC source; A rotor coil, which is inductively coupled to the excitation coil; Multiple receiver coils, the multiple receiver coils being coupled and inductively coupled to the rotor coil in a Y configuration; and A position sensor interface configured to receive multiple differential receiver signals from the plurality of receiver coils, the position sensor interface comprising: A modulator, configured to convert multiple digital feedback signals into multiple pulse density modulated (PDM) signals; and A multiplier configured to multiply the plurality of PDM signals by the plurality of differential receiver signals, the multiplier comprising: A plurality of analog multiplexers, the plurality of analog multiplexers being configured to receive signals from a plurality of differential receivers, each of the plurality of analog multiplexers having a differential multiplexer output coupled to the differential output of the multiplier; and A control circuit configured to control each of the plurality of analog multiplexers based on the plurality of PDM signals.

12. The position sensor system of claim 11, wherein, based on the plurality of PDM signals, each of the plurality of analog multiplexers is configured to provide one of the following: non-inverting rectification of a corresponding differential receiver signal among the plurality of differential receiver signals, inverting rectification of the corresponding differential receiver signal among the plurality of differential receiver signals, or high-impedance output.

13. The position sensor system of claim 11, wherein the modulator is a Σ-Δ modulator.

14. The position sensor system according to claim 11, further comprising: A low-pass filter, which is coupled to filter the differential output of the multiplier; A processing circuit configured to output a digital error signal based on a filter output; and A feedback circuit configured to generate multiple digital feedback signals based on the digital error signal.

15. The position sensor system of claim 14, wherein the processing circuit comprises: A transconductance amplifier configured to amplify the filter output; An integrator configured to integrate the output of the transconductance amplifier; and An analog-to-digital converter (ADC) is configured to receive the output of an integrator and generate the digital error signal.

16. A method for operating a position sensor interface, the method comprising: Receive signals from multiple differential receivers at multiple analog multiplexers; Convert multiple digital feedback signals into multiple pulse density modulated (PDM) signals; as well as The operation state of each of the plurality of analog multiplexers is controlled based on the plurality of PDM signals to multiply the plurality of differential receiver signals with the plurality of PDM signals.

17. The method according to claim 16, further comprising: Filter the output of the differential multiplier; Digital error signals are generated based on the filter output; as well as The plurality of digital feedback signals are generated based on the digital error signals.

18. The method of claim 16, wherein: The plurality of differential receiver signals include at least a first sine signal, a second sine signal, and a third sine signal based on the rotor angle of the position sensor; The plurality of digital feedback signals include at least a first cosine signal, a second cosine signal, and a third cosine signal based on digital angle values; and The first sine signal is multiplied by the first cosine signal, the second sine signal is multiplied by the second cosine signal, and the third sine signal is multiplied by the third cosine signal.

19. The method of claim 18, wherein: The plurality of differential receiver signals also include a fourth signal based at least on the excitation amplitude of the position sensor; The plurality of digital feedback signals also include at least a fourth cosine signal based on the digital angle value; and The fourth signal is multiplied by the fourth cosine signal.

20. The method of claim 16, wherein, based on the plurality of PDM signals, each of the plurality of analog multiplexers is configured to provide one of the following: non-inverting rectification of a corresponding differential receiver signal among the plurality of differential receiver signals, inverting rectification of the corresponding differential receiver signal among the plurality of differential receiver signals, or high-impedance operation.

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