Analog-to-digital converter-embedded fixed-phase variable gain amplifier stages for dual monitoring paths

Abstract

A delta-sigma modulator may include a loop filter, a quantizer, an input gain element having a programmable input gain and coupled between an input of the delta-sigma modulator and an input of the loop filter, a feedforward gain element having a programmable feedforward gain and coupled between the input of the delta-sigma modulator and an output of the loop filter, and a quantizer gain element having a quantizer gain and coupled between the output of the loop filter and an input of the quantizer. The programmable input gain is controlled in order to control a variable gain of the delta-sigma modulator. The programmable feedforward gain is controlled to be equal to the ratio of the programmable input gain and the quantizer gain such that the delta-sigma modulator has a fixed phase response.

Claims

1. A delta-sigma modulator comprising: a loop filter; a quantizer; an input gain element having a programmable input gain and coupled between an input of the delta-sigma modulator and an input of the loop filter; a feedforward gain element having a programmable feedforward gain and coupled between the input of the delta-sigma modulator and an output of the loop filter; and a quantizer gain element having a quantizer gain and coupled between the output of the loop filter and an input of the quantizer; wherein: the programmable input gain is controlled in order to control a variable gain of the delta-sigma modulator; and the programmable feedforward gain is controlled to be equal to the ratio of the programmable input gain and the quantizer gain such that the delta-sigma modulator has a fixed phase response.

2. The delta-sigma modulator of claim 1, wherein the quantizer gain is fixed.

3. The delta-sigma modulator of claim 1, wherein: the input of the loop filter is coupled to an output of the quantizer; and a feedback gain from the output of the quantizer to the input of the loop filter is one (1).

4. A method for controlling a fixed-phase gain amplifier embedded in an analog-to-digital converter, comprising: controlling an input gain element having a programmable input gain and coupled between an input of a delta-sigma modulator and an input of a loop filter of the delta-sigma modulator in order to control a variable gain of the delta-sigma modulator; and controlling a feedforward gain element having a programmable feedforward gain and coupled between the input of the delta-sigma modulator and an output of the loop filter to be equal to the ratio of the programmable input gain and a quantizer gain of a quantizer gain element coupled between the output of the loop filter and an input of a quantizer of the delta-sigma modulator, such that the delta-sigma modulator has a fixed phase response.

5. The method of claim 4, wherein the quantizer gain is fixed.

6. The method of claim 4, wherein: the input of the loop filter is coupled to an output of the quantizer; and a feedback gain from the output of the quantizer to the input of the loop filter is one (1).

7. A controller for controlling a fixed-phase gain amplifier embedded in an analog-to-digital converter, comprising: a first output for controlling an input gain element having a programmable input gain and coupled between an input of a delta-sigma modulator and an input of a loop filter of the delta-sigma modulator in order to control a variable gain of the delta-sigma modulator; a second output for controlling a feedforward gain element having a programmable feedforward gain and coupled between the input of the delta-sigma modulator and an output of the loop filter; and logic for controlling the feedforward gain element to be equal to the ratio of the programmable input gain and a quantizer gain of a quantizer gain element coupled between the output of the loop filter and an input of a quantizer of the delta-sigma modulator, such that the delta-sigma modulator has a fixed phase response.

8. The method of claim 7, wherein the quantizer gain is fixed.

9. The method of claim 7, wherein: the input of the loop filter is coupled to an output of the quantizer; and a feedback gain from the output of the quantizer to the input of the loop filter is one (1).

10. A system for measuring a plurality of physical quantities associated with an electrical component, the system comprising a plurality of sensing paths comprising: a first sensing path for sensing a first physical quantity associated with the electrical component; and a second sensing path for sensing a second physical quantity associated with the electrical component; wherein each of the first sensing path and the second sensing path respectively comprise a respective delta-sigma modulator that comprises: a loop filter; a quantizer; an input gain element having a programmable input gain and coupled between an input of the delta-sigma modulator and an input of the loop filter; a feedforward gain element having a programmable feedforward gain and coupled between the input of the delta-sigma modulator and an output of the loop filter; and a quantizer gain element having a quantizer gain and coupled between the output of the loop filter and an input of the quantizer; wherein: the programmable input gain is controlled in order to control a variable gain of the delta-sigma modulator; and the programmable feedforward gain is controlled to be equal to the ratio of the programmable input gain and the quantizer gain such that the delta-sigma modulator has a fixed phase response.

11. The system of claim 10, wherein the quantizer gain for each respective delta-sigma modulator is fixed.

12. The system of claim 10, wherein in each respective delta-sigma modulator: the input of the loop filter is coupled to an output of the quantizer; and a feedback gain from the output of the quantizer to the input of the loop filter is one (1).

13. The system of claim 10, wherein: the first physical quantity is a voltage associated with the electrical component; and the second physical quantity is a current associated with the electrical component.

14. The system of claim 10, wherein the electrical component comprises an electromagnetic transducer.

15. A device comprising: an electrical component; a driver configured to drive a waveform to the electrical component; and a measurement subsystem for measuring a plurality of physical quantities associated with the electrical component, the measurement subsystem comprising a plurality of sensing paths comprising: a first sensing path for sensing a first physical quantity associated with the electrical component; and a second sensing path for sensing a second physical quantity associated with the electrical component; wherein each of the first sensing path and the second sensing path respectively comprise a respective delta-sigma modulator that comprises: a loop filter; a quantizer; an input gain element having a programmable input gain and coupled between an input of the delta-sigma modulator and an input of the loop filter; a feedforward gain element having a programmable feedforward gain and coupled between the input of the delta-sigma modulator and an output of the loop filter; and a quantizer gain element having a quantizer gain and coupled between the output of the loop filter and an input of the quantizer; wherein: the programmable input gain is controlled in order to control a variable gain of the delta-sigma modulator; and the programmable feedforward gain is controlled to be equal to the ratio of the programmable input gain and the quantizer gain such that the delta-sigma modulator has a fixed phase response.

16. The device of claim 15, wherein the quantizer gain for each respective delta-sigma modulator is fixed.

17. The device of claim 15, wherein in each respective delta-sigma modulator: the input of the loop filter is coupled to an output of the quantizer; and a feedback gain from the output of the quantizer to the input of the loop filter is one (1).

18. The device of claim 15, wherein: the first physical quantity is a voltage associated with the electrical component; and the second physical quantity is a current associated with the electrical component.

19. The device of claim 15, wherein the electrical component comprises an electromagnetic transducer.

20. The device of claim 15, further comprising a control system configured to control the waveform based on the plurality of physical quantities.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A more complete understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein:

(2) FIG. 1 illustrates an example of a vibro-haptic system in a device, as is known in the art;

(3) FIG. 2 illustrates an example of a Linear Resonant Actuator (LRA) modelled as a linear system, as is known in the art;

(4) FIG. 3 illustrates selected components of an example host device, in accordance with embodiments of the present disclosure;

(5) FIG. 4 illustrates selected components of an example analog-to-digital subsystem, in accordance with embodiments of the present disclosure; and

(6) FIG. 5 illustrates selected components of an example delta-sigma modulator for use in an analog-to-digital converter, in accordance with embodiments of the present disclosure.

DETAILED DESCRIPTION

(7) The description below sets forth example embodiments according to this disclosure. Further example embodiments and implementations will be apparent to those having ordinary skill in the art. Further, those having ordinary skill in the art will recognize that various equivalent techniques may be applied in lieu of, or in conjunction with, the embodiment discussed below, and all such equivalents should be deemed as being encompassed by the present disclosure.

(8) Various electronic devices or smart devices may have transducers, speakers, and acoustic output transducers, for example any transducer for converting a suitable electrical driving signal into an acoustic output such as a sonic pressure wave or mechanical vibration. For example, many electronic devices may include one or more speakers or loudspeakers for sound generation, for example, for playback of audio content, voice communications and/or for providing audible notifications.

(9) Such speakers or loudspeakers may comprise an electromagnetic actuator, for example a voice coil motor, which is mechanically coupled to a flexible diaphragm, for example a conventional loudspeaker cone, or which is mechanically coupled to a surface of a device, for example the glass screen of a mobile device. Some electronic devices may also include acoustic output transducers capable of generating ultrasonic waves, for example for use in proximity detection-type applications and/or machine-to-machine communication.

(10) Many electronic devices may additionally or alternatively include more specialized acoustic output transducers, for example, haptic transducers, tailored for generating vibrations for haptic control feedback or notifications to a user. Additionally or alternatively, an electronic device may have a connector, e.g., a socket, for making a removable mating connection with a corresponding connector of an accessory apparatus, and may be arranged to provide a driving signal to the connector so as to drive a transducer, of one or more of the types mentioned above, of the accessory apparatus when connected. Such an electronic device will thus comprise driving circuitry for driving the transducer of the host device or connected accessory with a suitable driving signal. For acoustic or haptic transducers, the driving signal may generally be an analog time varying voltage signal, for example, a time varying waveform.

(11) To accurately sense displacement of an electromagnetic load, methods and systems of the present disclosure may determine an inductance of the electromagnetic load, and then convert the inductance to a position signal, as described in greater detail below. Further, to measure inductance of an electromagnetic load, methods and systems of the present disclosure may utilize either a phase measurement approach and/or a high-frequency pilot-tone driven approach, as also described in greater detail below.

(12) To illustrate, an electromagnetic load may be driven by a driving signal V(t) to generate a sensed terminal voltage V.sub.T (t) across a coil of the electromagnetic load. Sensed terminal voltage V.sub.T (t) may be given by:
V.sub.T(t)=—Z.sub.COILI(t)+V.sub.B(t)
wherein I(t) is a sensed current through the electromagnetic load, Z.sub.COIL, is an impedance of the electromagnetic load, and V.sub.B (t) is the back-electromotive force (back-EMF) associated with the electromagnetic load.

(13) As used herein, to “drive” an electromagnetic load means to generate and communicate a driving signal to the electromagnetic load to cause displacement of a movable mass of the electromagnetic load.

(14) Because back-EMF voltage V.sub.B (t) may be proportional to velocity of the moving mass of the electromagnetic load, back-EMF voltage V.sub.B (t) may in turn provide an estimate of such velocity. Thus, velocity of the moving mass may be recovered from sensed terminal voltage V.sub.T (t) and sensed current I(t) provided that either: (a) sensed current I(t) is equal to zero, in which case V.sub.B=V.sub.T; or (b) coil impedance Z.sub.COIL is known or is accurately estimated.

(15) Position of the moving mass may be related to a coil inductance L.sub.COIL of the electromagnetic load. At high frequencies significantly above the bandwidth of the electromagnetic load, back-EMF voltage V.sub.B (t) may become negligible and inductance may dominate the coil impedance Z.sub.COIL Sensed terminal voltage V.sub.T@HF(t) at high frequencies may be estimated by:
V.sub.T@HF(t)Z.sub.COILI.sub.@HF(t)

(16) Hence, at high frequencies, the position of the moving mass of the electromagnetic load may be recovered from sensed terminal voltage V.sub.T (t) and sensed current I(t) by: (a) estimating the coil impedance at high frequency as Z.sub.COIL@HF≅R.sub.@HF+L.sub.@HF.Math.S, where R.sub.@HF is the resistive part of the coil impedance at high frequency, L.sub.@HF is the coil inductance at high frequency, and s is the Laplace transform; and (b) converting the measured inductance to a position signal. Velocity and/or position may be used to control vibration of the moving mass of the electromagnetic load.

(17) FIG. 3 illustrates selected components of an example host device 300 having an electromagnetic load 301, in accordance with embodiments of the present disclosure. Host device 300 may include, without limitation, a mobile device, home application, vehicle, and/or any other system, device, or apparatus that includes a human-machine interface. Electromagnetic load 301 may include any suitable load with a complex impedance, including without limitation a haptic transducer, a loudspeaker, a microspeaker, a piezoelectric transducer, a voice-coil actuator, a solenoid, or other suitable transducer.

(18) In operation, a signal generator 324 of a processing subsystem 305 of host device 300 may generate a raw transducer driving signal x′(t) (which, in some embodiments, may be a waveform signal, such as a haptic waveform signal or audio signal). Raw transducer driving signal x′(t) may be generated based on a desired playback waveform received by signal generator 324.

(19) Raw transducer driving signal x′(t) may be received by waveform preprocessor 326 which may modify raw transducer driving signal x′(t) based on a limiting signal generated by inductance measurement subsystem 308 and/or based on any other factor in order to generate processed transducer driving signal x(t).

(20) Processed transducer driving signal x(t) may in turn be amplified by amplifier 306 to generate a driving signal V(t) for driving electromagnetic load 301. Responsive to driving signal V(t), a sensed terminal voltage V.sub.T (0 of electromagnetic load 301 may be sensed by a terminal voltage sensing block 307, for example a volt-meter, and converted to a digital representation by a first analog-to-digital conversion (ADC) subsystem 303. Similarly, sensed current I(t) may be converted to a digital representation by a second ADC subsystem 304. Current 1(t) may be sensed across a shunt resistor 302 having resistance R.sub.s coupled to a terminal of electromagnetic load 301.

(21) As shown in FIG. 3, processing subsystem 305 may include an inductance measurement subsystem 308 that may estimate coil inductance L.sub.COIL of electromagnetic load 301. From such estimated coil inductance L.sub.COIL, inductance measurement subsystem 308 may determine a displacement associated with electromagnetic load 301. If such displacement exceeds a threshold, high-frequency pilot-tone driven inductance measurement subsystem 308 may communicate a limiting signal (indicated by “LIMIT” in FIG. 3) to modify raw transducer driving signal x′(t) in a manner that prevents over-excursion in the displacement of electromagnetic load 301.

(22) In operation, to estimate impedance Z.sub.COIL, inductance measurement subsystem 308 may measure impedance in any suitable manner, including without limitation using the approaches set forth in U.S. patent application Ser. No. 17/497,110 filed Oct. 8, 2021, which is incorporated in its entirety by reference herein.

(23) In particular, because electromagnetic load 301 may have a complex impedance, including a resistive component and an inductive component, sensed terminal voltage V.sub.T(t) and sensed current I(t) may be out of phase with one another. Accordingly, based on the measured magnitudes of sensed terminal voltage V.sub.T (t) and sensed current I(t) and their relative phase differences, inductance measurement subsystem 308 may determine the complex impedance of electromagnetic load 301, including estimated coil inductance LcolL.

(24) However, because inductance measurement subsystem 308 may employ phase-based determination of the complex impedance of electromagnetic load 301, it may be critical that the phase delay of first ADC subsystem 303 and second ADC subsystem 304 remain equal and fixed. Further, in some embodiments, it may be desirable to independently modify signal path gains of first ADC subsystem 303 and second ADC subsystem 304 without also modifying the fixed phase delay of either of first ADC subsystem 303 and second ADC subsystem 304.

(25) FIG. 4 illustrates selected components of an example ADC subsystem 400, in accordance with embodiments of the present disclosure. ADC subsystem 400 as shown in FIG. 4 may be used to implement each of first ADC subsystem 303 and second ADC subsystem 304 depicted in FIG. 3.

(26) As shown in FIG. 4, ADC subsystem 400 may include an analog front end (AFE) 402 configured to receive an input voltage V.sub.in (e.g., sensed terminal voltage V.sub.T (t) and sensed current I(t)) and an ADC 404 coupled to the output of AFE 402 and further including an embedded fixed-phase variable-gain amplifier (VGA) 406.

(27) AFE 402 may include any system, device, or apparatus embodying analog signal conditioning circuitry (e.g., sensitive analog amplifiers, filters, and/or application-specific integrated circuits) configured to provide a configurable and flexible functional block to interface a component (e.g., electromagnetic load 301, sense resistor 302) to ADC 404.

(28) ADC 404 may include any system, device, or apparatus configured to receive an analog signal at its input and convert such analog signal to an equivalent digital signal. As shown in FIG. 4, ADC 404 may include embedded fixed-phase VGA 406. Fixed-phase VGA 406 may include a system, device, or apparatus configured to apply a programmable signal gain to a signal received at its input in order to amplify or attenuate such signal, all while maintaining a fixed phase relationship between its input and its output as the programmable signal gain varies.

(29) FIG. 5 illustrates selected components of an example delta-sigma modulator 500 for use in ADC 404, in accordance with embodiments of the present disclosure. In operation, delta-sigma modulator 500 may provide the analog-to-digital conversion functionality of ADC 404 as well as provide the fixed-phase variable-gain functionality of fixed-phase VGA 406.

(30) As shown in FIG. 5, delta-sigma modulator 500 may comprise an input gain element 502 having a variable gain k.sub.i and configured to receive an input signal IN (e.g., which may represent an input signal received by ADC 404). A feedback combiner 504 may receive a feedback signal from a feedback gain element 516 and subtract such feedback signal from the signal generated by input gain element 502. A loop filter 506 may apply a response H(z) to the signal output by combiner 504.

(31) Delta-sigma modulator 500 may also comprise a feedforward gain element 508 having a variable gain k.sub.f and also configured to receive input signal IN. A feedforward combiner 510 may sum the signal output by loop filter 506 and the signal output by feedforward gain element 508.

(32) Delta-sigma modulator 500 may further include a quantizer gain element 512 having a fixed gain k.sub.q and configured to receive the signal output by combiner 510. Quantizer 514 may quantize the signal output by quantizer gain element 512 in order to generate a digitized output signal OUT (e.g., which may be or may otherwise correspond to the output of ADC 404).

(33) Delta-sigma modulator 500 may additionally include feedback gain element 516 having a fixed gain k.sub.d and configured to receive digitized output signal OUT. Those of skill in the art may recognize that the signal transfer function of delta-sigma modulator 500 may be given by:

(34) $\frac{k_{f} k_{q} + k_{i} k_{q} H (s)}{1 + k_{d} k_{q} H (s)}$

(35) which may be rewritten as:

(36) $k_{i} \frac{\frac{k_{f}}{k_{i}} + H (s)}{\frac{1}{k_{q}} + k_{d} H (s)}$

(37) With such a signal transfer function, if k.sub.f=k.sub.i/k.sub.q and k.sub.d=1, the signal transfer function simplifies to k.sub.i, which renders such transfer function equivalent to an all-pass filter with a variable gain provided k.sub.f is also varied to track if k.sub.f=k.sub.i/k.sub.g.

(38) In the systems and methods described above, a fixed-phase variable gain enables an overall system that is monitoring the two phase-sensitive quantities (e.g., sensed terminal voltage V.sub.T (t) and sensed current I(t)) to have an independent gain control without having an impact on the relative phase response between the monitored quantities. Independent gain control implementation using AFEs, as may be performed using traditional approaches, may have an impact on the relative phase response between the two monitored quantities. However, the fixed-phase VGA embedded within an ADC has little or no phase sensitivity because the signal transfer function for the embedded VGA has its signal transfer poles that are cancelled out by signal transfer zeroes.

(39) As used herein, when two or more elements are referred to as “coupled” to one another, such term indicates that such two or more elements are in electronic communication or mechanical communication, as applicable, whether connected indirectly or directly, with or without intervening elements.

(40) This disclosure encompasses all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Similarly, where appropriate, the appended claims encompass all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Moreover, reference in the appended claims to an apparatus or system or a component of an apparatus or system being adapted to, arranged to, capable of, configured to, enabled to, operable to, or operative to perform a particular function encompasses that apparatus, system, or component, whether or not it or that particular function is activated, turned on, or unlocked, as long as that apparatus, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative. Accordingly, modifications, additions, or omissions may be made to the systems, apparatuses, and methods described herein without departing from the scope of the disclosure. For example, the components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses disclosed herein may be performed by more, fewer, or other components and the methods described may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order. As used in this document, “each” refers to each member of a set or each member of a subset of a set.

(41) Although exemplary embodiments are illustrated in the figures and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should in no way be limited to the exemplary implementations and techniques illustrated in the drawings and described above.

(42) Unless otherwise specifically noted, articles depicted in the drawings are not necessarily drawn to scale.

(43) All examples and conditional language recited herein are intended for pedagogical objects to aid the reader in understanding the disclosure and the concepts contributed by the inventor to furthering the art, and are construed as being without limitation to such specifically recited examples and conditions. Although embodiments of the present disclosure have been described in detail, it should be understood that various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the disclosure.

(44) Although specific advantages have been enumerated above, various embodiments may include some, none, or all of the enumerated advantages. Additionally, other technical advantages may become readily apparent to one of ordinary skill in the art after review of the foregoing figures and description.

(45) To aid the Patent Office and any readers of any patent issued on this application in interpreting the claims appended hereto, applicants wish to note that they do not intend any of the appended claims or claim elements to invoke 35 U.S.C. § 112(f) unless the words “means for” or “step for” are explicitly used in the particular claim.

Analog-to-digital converter-embedded fixed-phase variable gain amplifier stages for dual monitoring paths

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Abstract

Claims

Description