US-12627927-B2 - Fast response audio signal processing system

US12627927B2US 12627927 B2US12627927 B2US 12627927B2US-12627927-B2

Abstract

The disclosure pertains to an audio signal processing system that offers low latency without sacrificing various desirable features such as large dynamic operating range and low power consumption. Low latency is achieved by generating a feed-forward signal that is based in part on performing high-pass filtering and threshold crossing detection upon an amplified transducer signal. The feed-forward signal is provided to a controller, which uses the feed-forward signal to produce a feedback signal that controls one or more operating parameters of one or more components of the audio signal processing system. The feedback signal produced in this manner avoids incurring a delay associated with propagating the amplified transducer signal to the controller via an analog-to-digital converter (ADC) for purposes of generating the feedback signal. Generation, and use, of the feed-forward signal also allows the audio amplifier to rapidly adjust to amplitude changes in audio signals received from the transducer.

Inventors

Dongyang Tang
Michael Carfore

Assignees

QUALCOMM INCORPORATED

Dates

Publication Date: 20260512
Application Date: 20240326

Claims (20)

1 . An audio signal processing system comprising: a transducer; a front-end amplifier configured to produce an amplified signal based on amplifying a transducer signal produced by the transducer; a feed-forward signal generator configured to produce a feed-forward signal, the feed-forward signal generator comprising a high-pass filter circuit and a comparator circuit, the comparator circuit configured to perform a threshold crossing functionality upon a portion of the amplified signal propagated through the high-pass filter circuit; and a controller configured to receive the feed-forward signal from the feed-forward signal generator and produce a feedback signal that controls at least one operating parameter of at least the front-end amplifier.
2 . The audio signal processing system of claim 1 , further comprising: an analog-to-digital converter configured to perform an analog-to-digital conversion upon the amplified signal produced by the front-end amplifier, the analog-to-digital conversion based at least in part on at least one operating parameter of the analog-to-digital converter being controlled by the feedback signal.
3 . The audio signal processing system of claim 1 , wherein the feed-forward signal generator further comprises: a reference voltage generator coupled with the comparator circuit, the reference voltage generator configured to produce a positive threshold reference voltage and a negative threshold reference voltage; and a pulse-extender circuit coupled with the comparator circuit, the pulse-extender circuit configured to produce the feed-forward signal based on extending a width of a signal output of the comparator circuit.
4 . The audio signal processing system of claim 1 , wherein the high-pass filter circuit comprises: a first capacitor having a first terminal and a second terminal, the first terminal coupled to a first input node of the high-pass filter circuit and the second terminal coupled to a first output node of the high-pass filter circuit; a first capacitor pre-charging circuit coupled to the second terminal of the first capacitor, the first capacitor pre-charging circuit configured to pre-charge the first capacitor under control of a first fast charge enable signal; and a first resistive element coupled to the second terminal of the first capacitor, the first resistive element comprising: a first transistor configured to provide a first bias voltage; a second transistor configured to provide a second bias voltage; a third transistor having a first terminal coupled to the second terminal of the first capacitor; and a fourth transistor coupled with the third transistor, the third transistor configured to operate based on the second bias voltage and the fourth transistor configured to operate based on the first bias voltage.
5 . The audio signal processing system of claim 4 , wherein the first transistor is a first NMOS transistor, the second transistor is a first PMOS transistor, the third transistor is a second PMOS transistor, and the fourth transistor is a second NMOS transistor, and wherein the first capacitor pre-charging circuit comprises at least one transistor having a first terminal coupled to the second terminal of the first capacitor, the at least one transistor arranged to be placed in a conduction state under control of the first fast charge enable signal for pre-charging the first capacitor.
6 . The audio signal processing system of claim 5 , wherein the at least one transistor having the first terminal coupled to the second terminal of the first capacitor comprises a fifth transistor coupled to a sixth transistor in a back-to-back diode configuration, and wherein an amount of current flowing through the fifth transistor and the sixth transistor is based on the first fast charge enable signal.
7 . The audio signal processing system of claim 5 , wherein each of a source terminal of the first NMOS transistor and a source terminal of the first PMOS transistor is coupled to a node that is a common mode voltage.
8 . The audio signal processing system of claim 4 , wherein the high-pass filter circuit is a differential high-pass filter circuit further comprising: a second capacitor having a first terminal and a second terminal, the first terminal of the second capacitor coupled to a second input node of the differential high-pass filter circuit and the second terminal of the second capacitor coupled to a second output node of the differential high-pass filter circuit; a second capacitor pre-charging circuit coupled to the second terminal of the second capacitor, the second capacitor pre-charging circuit configured to pre-charge the second capacitor under control of a second fast charge enable signal; and a second resistive element coupled to the second terminal of the second capacitor, the second resistive element comprising: a fifth transistor configured to provide a third bias voltage; a sixth transistor configured to provide a fourth bias voltage, wherein the fourth bias voltage is lower than the third bias voltage; and a seventh transistor having a first terminal coupled to the second terminal of the second capacitor; and an eighth transistor coupled with the seventh transistor, the eighth transistor configured to operate based on the third bias voltage and the seventh transistor configured to operate based on the fourth bias voltage.
9 . The audio signal processing system of claim 8 , wherein the fifth transistor is a first NMOS transistor, the sixth transistor is a first PMOS transistor, the seventh transistor is a second PMOS transistor, and the eighth transistor is a second NMOS transistor, and wherein the second capacitor pre-charging circuit comprises at least one transistor having a first terminal coupled to the second terminal of the second capacitor, the at least one transistor arranged to be placed in a conduction state under control of the second fast charge enable signal for pre-charging the second capacitor.
10 . The audio signal processing system of claim 8 , wherein the comparator circuit comprises: a pair of comparators coupled with a Schmitt trigger comparator, the pair of comparators configured to compare the portion of the amplified signal propagated through the high-pass filter circuit to a positive threshold reference voltage and a negative threshold reference voltage.
11 . A method of operation of an audio signal processing system, comprising: producing, by a transducer, a transducer signal; producing, by a front-end amplifier, an amplified signal based on amplifying the transducer signal; producing, by a feed-forward signal generator, a feed-forward signal based at least in part, on performing a threshold crossing functionality upon a portion of the amplified signal propagated through a high-pass filter circuit; producing, by a controller, based at least in part, on the feed-forward signal, a feedback signal; and using the feedback signal to control at least one operating parameter of at least the front-end amplifier.
12 . The method of claim 11 , wherein performing the threshold crossing functionality comprises: using a comparator circuit to compare the portion of the amplified signal propagated through the high-pass filter circuit with a pair of threshold reference voltages.
13 . The method of claim 11 , wherein the high-pass filter circuit comprises a first capacitor and a first resistive element, and wherein the method further comprises: configuring the first resistive element to offer a first resistance based on applying a first bias voltage to a first transistor that is a part of the first resistive element.
14 . The method of claim 13 , wherein configuring the first resistive element to offer the first resistance is further based on applying a second bias voltage to a second transistor that is a part of the first resistive element, the second transistor coupled with the first transistor.
15 . The method of claim 13 , further comprising: pre-charging the first capacitor by applying a first fast charge to the first capacitor.
16 . The method of claim 13 , wherein performing the threshold crossing functionality comprises: using a pair of comparators to compare the portion of the amplified signal propagated through the high-pass filter circuit to a positive threshold reference voltage and a negative threshold reference voltage; and producing narrow-width signals based on a coupling an output of the pair of comparators to a Schmitt trigger comparator.
17 . The method of claim 16 , further comprising: producing the feed-forward signal based on using a pulse extender circuit to extend a width of the narrow-width signals produced by the Schmitt trigger comparator.
18 . An audio signal processing system, comprising: means for producing an amplified signal based on amplifying a transducer signal produced by a transducer; means for producing a feed-forward signal based at least in part on performing a threshold crossing functionality upon a portion of the amplified signal propagated through a high-pass filter circuit; means for producing, based at least in part, on the feed-forward signal, a feedback signal; and means for using the feedback signal to control at least one operating parameter of at least one component of the audio signal processing system.
19 . The audio signal processing system of claim 18 , wherein means for producing the feed-forward signal comprises: means for comparing the portion of the amplified signal propagated through the high-pass filter circuit with a pair of threshold reference voltages.
20 . The audio signal processing system of claim 19 , wherein propagating the amplified signal through the high-pass filter circuit comprises: means for coupling the amplified signal into the high-pass filter circuit, the high-pass filter circuit comprising a capacitor and a resistive element; and means for configuring the resistive element to offer a resistance based on applying a first bias voltage to a first transistor that is a part of the resistive element and a second bias voltage to a second transistor that is a part of the resistive element.

Description

BACKGROUND 1. Field of Disclosure The present disclosure relates generally to the field of audio signal processing and more specifically to a fast response audio signal processing system. 2. Description of Related Art An audio signal processing system can be typically used to perform various operations upon audio signals, such as, for example, signal amplification with a desired signal-to-noise ratio, filtering, and digitizing. In some cases, at least some components of the audio signal processing system (such as, for example, a transducer and an audio amplifier) can be housed in an integrated circuit having a small form factor. The audio amplifier may offer various features associated with parameters such as gain, power consumption, bandwidth, and distortion. Some designers may opt to make trade-offs between some of these features. For example, a designer may opt to obtain a better gain-bandwidth product by sacrificing an amount of gain. BRIEF SUMMARY An example audio signal processing system can include a transducer, a front-end amplifier, a feed-forward signal generator, and a controller. The front-end amplifier is configured to produce an amplified signal based on amplifying a transducer signal produced by the transducer. The feed-forward signal generator, which is configured to produce a feed-forward signal, can include a high-pass filter circuit and a comparator circuit. The comparator circuit is configured to perform a threshold crossing functionality upon a portion of the amplified signal propagated through the high-pass filter circuit. The controller is configured to receive the feed-forward signal from the feed-forward signal generator and produce a feedback signal that controls at least one operating parameter of at least the front-end amplifier. An example method of operation of an audio signal processing system can include producing, by a transducer, a transducer signal; producing, by a front-end amplifier, an amplified signal based on amplifying the transducer signal; producing, by a feed-forward signal generator, a feed-forward signal based at least in part, on performing a threshold crossing functionality upon a portion of the amplified signal propagated through a high-pass filter circuit; producing, by a controller, based at least in part, on the feed-forward signal, a feedback signal; and using the feedback signal to control at least one operating parameter of at least the front-end amplifier. An example audio signal processing system includes means for producing an amplified signal based on amplifying a transducer signal produced by a transducer; means for producing a feed-forward signal based at least in part on performing a threshold crossing functionality upon a portion of the amplified signal propagated through a high-pass filter circuit; means for producing, based at least in part, on the feed-forward signal, a feedback signal; and means for using the feedback signal to control at least one operating parameter of at least one component of the audio signal processing system. This summary is neither intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification of this disclosure, any or all drawings, and each claim. The foregoing, together with other features and examples, will be described in more detail below in the following specification, claims, and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The detailed description below pertains to a few example embodiments that are illustrated in the accompanying drawings. However, it must be understood that the description is equally relevant to various other variations of the embodiments described herein. Such embodiments may utilize objects and/or components other than those illustrated in the drawings. It must also be understood that like reference numerals used in the various figures indicate similar or identical objects. FIG. 1 shows some functional blocks of a fast response audio signal processing system according to an embodiment. FIG. 2 shows some functional blocks of a feed-forward signal generator that can be a part of the fast response audio signal processing system shown in FIG. 1. FIG. 3 shows some example components of a high-pass filter circuit that can be a part of the feed-forward signal generator shown in FIG. 2. FIG. 4 shows an example implementation of a high-pass filter circuit that can be a part of the feed-forward signal generator shown in FIG. 2. FIG. 5 shows an example implementation of a dual-differential comparator and a pulse extender circuit that can be included in the feed-forward signal generator shown in FIG. 2. FIG. 6 illustrates a flowchart of a method of operation of an audio signal processing system in accordance with an embodiment of the disclosure. DETAILED DESCRIPTION Several i