AMPLIFIER CIRCUITRY

Integrated circuitry implementing amplifier circuitry, the integrated circuitry comprising first amplifier circuitry and second amplifier circuitry, the first and second amplifier circuitry being configurable as first and second single-ended amplifiers or as a differential amplifier, wherein the first amplifier circuitry comprises: a first input stage; a first half-bridge output stage having an output coupled to a first output terminal of the integrated circuitry; a first feedback path coupling a first input of the first input stage to a first sense terminal of the first amplifier circuitry; a second feedback path coupling a second input of the first input stage to a second sense terminal of the first amplifier circuitry; and a first shunt resistor coupling the output of the first half-bridge output stage to the first feedback path, wherein the second amplifier circuitry comprises: a second input stage; and a second half-bridge output stage having an output coupled to a second output terminal of the integrated circuitry, and wherein the first amplifier circuitry further comprises a second shunt resistor coupling the second feedback path to a dedicated shunt resistor terminal of the integrated circuitry, such that the second shunt resistor is directly accessible from outside the integrated circuitry.

FIELD OF THE INVENTION

The present disclosure relates to amplifier circuitry, and in particular to integrated circuitry implementing amplifier circuitry.

BACKGROUND

Amplifier circuitry may be implemented by discrete electronic components mounted on a suitable substrate such as a printed circuitry board (PCB), or may be implemented in integrated circuit (IC) devices. An IC device implementing amplifier circuitry may comprise two single ended half-bridge amplifiers for driving separate loads, but which may be reconfigured as a full-bridge differential amplifier for driving a single load.

SUMMARY

According to a first aspect, the invention provides integrated circuitry implementing amplifier circuitry, the integrated circuitry comprising first amplifier circuitry and second amplifier circuitry, the first and second amplifier circuitry being configurable as first and second single-ended amplifiers or as a differential amplifier,wherein the first amplifier circuitry comprises:a first input stage;a first half-bridge output stage having an output coupled to a first output terminal of the integrated circuitry;a first feedback path coupling a first input of the first input stage to a first sense terminal of the first amplifier circuitry;a second feedback path coupling a second input of the first input stage to a second sense terminal of the first amplifier circuitry; anda first shunt resistor coupling the output of the first half-bridge output stage to the first feedback path,wherein the second amplifier circuitry comprises:a second input stage; anda second half-bridge output stage having an output coupled to a second output terminal of the integrated circuitry,and wherein the first amplifier circuitry further comprises a second shunt resistor coupling the second feedback path to a dedicated shunt resistor terminal of the integrated circuitry, such that the second shunt resistor is directly accessible from outside the integrated circuitry.

The first amplifier circuitry may comprise a first return path switch in a first return path, for selectively coupling an amplifier return terminal of the first amplifier circuitry to a ground or reference voltage supply terminal of the first amplifier circuitry.

The second amplifier circuitry may comprise a second return path switch in a second return path for selectively coupling an amplifier return terminal of the second amplifier circuitry to a ground or reference voltage supply terminal of the second amplifier circuitry.

The first amplifier circuitry may comprise load sensing circuitry coupled to the amplifier return terminal of the first circuitry, for determining a parameter of a load coupled to the first output terminal.

The second amplifier circuitry may comprise load sensing circuitry coupled to the amplifier return terminal of the second circuitry, for determining a parameter of a load coupled to the second output terminal.

The first amplifier circuitry may comprise Class D amplifier circuitry.

The first input stage may comprise pulse width modulator circuitry.

The second amplifier circuitry may further comprise:a second input stage;a third feedback path coupling a first input of the second input stage to a first sense terminal of the second amplifier circuitry;a fourth feedback path coupling a second input of the second input stage to a second sense terminal of the second amplifier circuitry;a third shunt resistor coupling the output of the second half-bridge output stage to the third feedback path; anda second shunt resistor coupling the second feedback path to an amplifier return terminal of the second amplifier circuitry.

The second amplifier circuitry may comprise class D amplifier circuitry.

The second input stage may comprise pulse width modulator circuitry.

In operation of the integrated circuitry when configured as a differential amplifier, the first input stage may be configured to supply input signals to the first half-bridge output stage and to the second half-bridge output stage.

In operation of the integrated circuitry when configured as first and second single-ended amplifiers, the first input stage may be configured to supply an input signal to the first half-bridge output stage and the second input stage may be configured to supply an input signal to the second half-bridge output stage.

According to a second aspect, the invention provides reconfigurable amplifier circuitry comprising:a first amplifier comprising:a first input stage;a first output stage;a first feedback path coupled to a first input of the first input stage;a second feedback path coupled to a second input of the first input stage;a first resistor coupling an output node of the first output stage to the first feedback path; anda second resistor coupled between a dedicated resistor node and the second feedback path; anda second amplifier comprising:a second input stage;a second output stage;a third feedback path coupled to a first input of the second input stage;a fourth feedback path coupled to a second input of the first input stage;a third resistor coupling an output node of the second output stage to the third feedback path; anda fourth resistor coupled between an amplifier return terminal and the second feedback path;wherein the reconfigurable amplifier circuitry is operable in:a first configuration as first and second amplifiers for driving respective first and second loads coupled to the respective output nodes of the first and second output stages; anda second configuration for differentially driving a single load coupled between the respective output nodes of the first and second output stages,wherein in the second configuration the output node of the second output stage is coupled to the dedicated resistor node of the first amplifier circuitry.

According to a third aspect, the invention provides reconfigurable amplifier circuitry comprising:first amplifier circuitry comprising a first input stage, a first output stage and a feedback path coupling an output node of the first output stage to a first input of the first input stage, wherein the feedback path comprises a first shunt resistor;second amplifier circuitry comprising a second input stage, a second output stage and a feedback path coupling an output node of the second output stage to a first input of the second input stage, wherein the feedback path comprises a second shunt resistor; anda selectable feedback path coupling the output node of the second output stage to a second input of the first input stage,wherein:in a first configuration the reconfigurable amplifier circuitry is operable as first and second single-ended amplifiers for driving respective first and second loads, wherein in the first configuration the selectable feedback path is disabled, the first input stage is operative to supply a first input signal to the first output stage and the second input stage is operative to supply a second input signal to the second output stage; andin a second configuration the reconfigurable amplifier circuitry is operable as a differential amplifier for driving a single load, wherein in the second configuration the selectable feedback path is enabled and the first input stage is operative to supply input signals to the first and second output stages.

The first amplifier circuitry may comprise a selectable second feedback path between a first amplifier return terminal and the second input of the first input stage, wherein in the first configuration the selectable second feedback path is enabled, and wherein in the second configuration the selectable second feedback path is disabled.

According to a fourth aspect the invention provides an integrated circuit comprising reconfigurable amplifier circuitry according to the second aspect or the third aspect.

According to a fifth aspect, the invention provides an integrated circuit comprising first amplifier circuitry, second amplifier circuitry and a shunt resistor associated with the first amplifier circuitry, wherein the first amplifier circuitry and the second amplifier circuitry are reconfigurable to implement either: separate first and second single-ended amplifier circuitry; or differential amplifier circuitry, and wherein the integrated circuit includes a dedicated resistor terminal to permit external access to the shunt resistor.

According to a sixth aspect, the invention provides a host device comprising integrated circuitry according to the first aspect.

The host device may comprise a laptop, notebook, netbook or tablet computer, a gaming device, a games console, a controller for a games console, a virtual reality (VR) or augmented reality (AR) device, a mobile telephone, a portable audio player, a portable device, an accessory device for use with a laptop, notebook, netbook or tablet computer, a gaming device, a games console a VR or AR device, a mobile telephone, a portable audio player or other portable device.

DETAILED DESCRIPTION

Referring first toFIG.1, an integrated circuit (IC) implementing amplifier circuitry is shown generally at100. The IC100in this example comprises first amplifier circuitry110(shown in dashed outline) and second amplifier circuitry150(also shown in dashed outline), which are configurable as two separate single ended half-bridge amplifiers (as shown inFIG.1), or as a single differential full-bridge amplifier (as shown inFIG.2).

The first amplifier circuitry110comprises a first input stage120and a first half-bridge output stage130. Outputs of the first input stage120are coupled to inputs of the first half-bridge output stage.

The first input stage120may comprise PWM modulator circuitry, for example.

In the example shown inFIG.1the first half-bridge output stage130comprises first and second complementary MOSFET devices coupled together in a half-bridge arrangement of a kind that will be familiar those of ordinary skill in the art.

The first half-bridge output stage130is coupled to a supply voltage terminal (e.g. a pin, pad ball or the like)112and to a ground or other reference voltage supply terminal114of the first amplifier circuitry110. An output node132of the first half-bridge output stage130is coupled to a first amplifier output terminal (e.g. a pin, pad ball or the like)116of the first amplifier circuitry110.

A first feedback path122acomprising a first feedback resistor124acouples a first input of the first input stage120to a first voltage sense terminal126of the first amplifier circuitry110. A first shunt resistor134is coupled, at a first terminal thereof, to the first feedback path122aand, at a second terminal thereof, to the output node132of the first half-bridge output stage130.

A second feedback path122bcomprising a second feedback resistor124bcouples a second input of the first input stage120to a second voltage sense terminal128of the first amplifier circuitry110. A second shunt resistor136is coupled between the second feedback path122band a first amplifier return terminal118of the first amplifier circuitry110.

In the example illustrated inFIG.1the first amplifier circuitry110further comprises a return path switch140in a return path142between the first amplifier return terminal118and the ground or other reference voltage supply terminal114. The return path switch140can be closed (e.g. in a load driving mode of operation of the first amplifier circuitry110) to couple the first amplifier return terminal118to the ground or other reference voltage supply terminal114, or opened (e.g. in a load sensing mode of operation of the first amplifier circuitry110) to decouple the first amplifier return terminal118from the ground or other reference supply terminal114. In other examples, however, the return path switch140may be omitted.

The first amplifier circuitry110may further include load sensing circuitry144, coupled to the first amplifier return terminal118and configured to detect, estimate or otherwise determine a parameter, property or characteristic (e.g. an impedance, inductance, resistance, capacitance or the like) of a first load105which is external to the IC100and which, in use of the IC100, is coupled between the first amplifier output terminal116and the first amplifier return terminal118.

The second amplifier circuitry150is similar to the first amplifier circuitry110, and comprises a second input stage160and a second half-bridge output stage170. Outputs of the second input stage160are coupled to inputs of the second half-bridge output stage170.

The second input stage160may comprise PWM modulator circuitry, for example.

In the example shown inFIG.1the second half-bridge output stage170comprises first and second complementary MOSFET devices coupled together in a half-bridge arrangement of a kind that will be familiar those of ordinary skill in the art. The second half-bridge output stage170is coupled to a supply voltage terminal (e.g. a pin, pad ball or the like)152and to a ground or other reference voltage supply terminal154of the second amplifier circuitry150. An output node172of the second half-bridge output stage170is coupled to a second amplifier output terminal (e.g. a pin, pad ball or the like)156of the second amplifier circuitry150.

A third feedback path162acomprising a third feedback resistor164acouples a first input of the second input stage160to a first voltage sense terminal166of the second amplifier circuitry150. A third shunt resistor174is coupled, at a first terminal, to the third feedback path162aand, at a second terminal, to the output node172of the second half-bridge output stage170.

A fourth feedback path162bcomprising a fourth feedback resistor164bcouples a second input of the second input stage160to a second voltage sense terminal168of the second amplifier circuitry150. A fourth shunt resistor176is coupled between the fourth feedback path162band a second amplifier return terminal158of the second amplifier circuitry150.

In the example illustrated inFIG.1the second amplifier circuitry150further comprises a return path switch180in a return path182between the second amplifier return terminal158and the ground or other reference voltage supply terminal154. The return path switch180can be closed (e.g. in a load driving mode of operation of the second amplifier circuitry150) to couple the second amplifier return terminal158to the ground or other reference voltage supply terminal154, or opened (e.g. in a load sensing mode of operation of the second amplifier circuitry150) to decouple the second amplifier return terminal158from the ground or other reference supply terminal154. In other examples, however, the return path switch180may be omitted.

The second amplifier circuitry150may further include load sensing circuitry186, coupled to the second amplifier return terminal158and configured to detect, estimate or otherwise determine a parameter, property or characteristic (e.g. an impedance, inductance, resistance, capacitance or the like) of a second load155which is external to the IC100and which, in use of the IC100, is coupled between the second amplifier output terminal156and the second amplifier return terminal158.

In operation of the first amplifier circuitry110as a single-ended amplifier to drive a first external load105(e.g. an audio transducer such as a speaker or a haptics transducer such as a linear resonant actuator), the first external load105is coupled between the first amplifier output terminal116and the first amplifier return terminal118of the first amplifier circuitry110.

In some applications, a first link or connection102external to the IC100may be provided to couple the first amplifier output terminal116to the first voltage sense terminal126, and a second link or connection104external to the IC100may be provided to couple the first amplifier return terminal to the second voltage sense terminal128. Thus, a feedback path containing only the first feedback resistor124amay be established between the first amplifier output terminal116and the first input of the first input stage120, and a feedback path containing only the second feedback resistor124bmay be established between the first amplifier return terminal118and the second input of the first input stage120.

In other applications the first and second links or connections102,104external to the IC100may not be provided. In such applications, or in a situation in which the first and second links or connections102,104are broken, a feedback path containing the first shunt resistor134and the first feedback resistor124ais provided between the first amplifier output terminal116of the first amplifier circuitry110and the first input of the first input stage120. Similarly, a feedback path containing the second shunt resistor136and the second feedback resistor124bis provided between the first amplifier return terminal118and the second input of the first input stage120.

Thus, in operation of the first amplifier circuitry110, the first and second shunt resistors134,136ensure that feedback paths are provided between the first amplifier output terminal116and the first input of the first input stage120and between the first amplifier return terminal118and the second input of the first input stage120. Thus, the first amplifier circuitry110always has a closed loop configuration, regardless of whether the first and second external links or connections102,104are provided, because the first and second shunt resistors134,136couple the first and second voltage sense terminals126,128to the respective first and second feedback paths122a,122b.

The second amplifier circuitry150can be configured in the same manner to operate as a single-ended amplifier to drive a second external load155coupled between the second amplifier output terminal156and the second amplifier return terminal158. A third external link or connection106may be provided between the second amplifier output terminal156and the first voltage sense terminal166of the second amplifier circuitry150to provide a feedback path containing only the third feedback resistor164abetween the second amplifier output terminal156and the first input of the second input stage160. A fourth external link or connection108may also be provided between the second amplifier return terminal158and the second voltage sense terminal168of the second amplifier circuitry150, to provide a feedback path containing only the fourth feedback resistor164bbetween the second amplifier return terminal158and the second input of the second input stage160.

Alternatively, if the third and fourth external links or connections106,108are not provided, or are broken, a feedback path containing the third shunt resistor174and the third feedback resistor164ais provided between the second amplifier output terminal156of the second amplifier circuitry150and the first input of the second input stage160. Similarly, a feedback path containing the fourth shunt resistor176and the fourth feedback resistor164bis provided between the second amplifier return terminal158and the second input of the second input stage160of the second amplifier circuitry150, to ensure that the second amplifier circuitry150always operates in a closed-loop configuration.

FIG.2is a schematic representation of the IC100ofFIG.1reconfigured as a differential full-bridge amplifier for driving a single load200.

As can be seen inFIG.2, in this configuration the load200(which is external to the IC100) is coupled between the first amplifier output terminal116and the second amplifier output terminal156, and the first input stage120provides input signals to both the first half-bridge output stage130and the second half-bridge output stage170, such that the external load200is driven by a differential output signal pair provided by the first and second first half-bridge output stages130,170. The second input stage160is not used.

A first external link or connection102is provided to couple the first amplifier output terminal116to the first voltage sense terminal126, thus providing a feedback path (containing the first feedback resistor124aof the first amplifier circuitry110) between the first amplifier output terminal116and the first input of the first input stage120. A fifth external link or connection202is provided to couple the second amplifier output terminal156to the second voltage sense terminal128of the first amplifier circuitry110, thus providing a feedback path (containing the second feedback resistor124bof the first amplifier circuitry110) between the second amplifier output terminal156and the second input of the first input stage120.

In this configuration the second shunt resistor136is isolated and thus cannot form part of a feedback path between the load200and the second input of the first input stage120. Thus, if the fifth external link or connection202is broken or not provided, the first amplifier circuitry110will adopt an open-loop configuration, which may lead to problems of instability and the like.

FIG.3is a schematic diagram illustrating an alternative IC implementation of amplifier circuitry. The IC, shown generally at300inFIG.3, includes a number of features in common with the IC100ofFIGS.1and2. Such common features are denoted by common reference numerals inFIGS.1,2and3, and will not be described again in detail here for the sake of clarity and brevity.

The IC300comprises first and second amplifier circuitry310,350that are similar to the first and second amplifier circuitry110,150described above with reference toFIG.1.

The first amplifier circuitry310differs from the first amplifier circuitry110ofFIG.1in that there is no first amplifier return terminal118, and no return path switch140is provided. Instead, the first half-bridge output stage130is coupled directly to the ground or other reference voltage supply terminal114of the first amplifier circuitry110by a first amplifier ground path312. A first terminal of the second shunt resistor136of the first amplifier circuitry310is coupled to the first amplifier ground path312, and a second terminal of the second shunt resistor136is coupled to the second voltage sense terminal128of the first amplifier circuitry310.

Similarly, the second amplifier circuitry350differs from the second amplifier circuitry150ofFIG.1in that there is no second amplifier return terminal158, and no return path switch180is provided. Instead, the second half-bridge output stage170is coupled directly to the ground or other reference voltage supply terminal154of the second amplifier circuitry150by a second amplifier ground path352. A first terminal of the fourth shunt resistor176of the second amplifier circuitry350is coupled to the second amplifier ground path352, and a second terminal of the fourth shunt resistor176is coupled to the second voltage sense terminal168of the second amplifier circuitry350.

In use of the IC300in the configuration shown inFIG.3to provide two single-ended half-bridge amplifiers for driving separate loads, a first terminal of a first load105(e.g. a transducer such as a speaker or an actuator such as a linear resonant actuator) external to the IC100is coupled to the first amplifier output terminal116. A second terminal of the first external load105is coupled to the ground or other reference voltage supply terminal114of the first amplifier circuitry310. The second terminal of the first external load105is also coupled to the second voltage sense terminal128of the first amplifier circuitry310. A first external link or connection102may be provided, coupled between the first amplifier output terminal116and the first voltage sense terminal126of the first amplifier circuitry310.

Thus, a feedback path is provided from the output node132of the first half-bridge output stage130to the first input of the first input stage120, either via the first external link or connection102(if provided) and the first feedback resistor124aor via the first shunt resistor134and the first feedback resistor124aif the first external link or connection102is not provided.

A feedback path is also provided from the second terminal of the first load105to the second input of the first input stage120, via the second feedback resistor124b.

Similarly, a first terminal of a second load155external to the IC100is coupled to the second amplifier output terminal156, and a second terminal of the second external load155is coupled to the ground or other reference voltage supply terminal154of the second amplifier circuitry350. The second terminal of the second external load155is also coupled to the second voltage sense terminal168of the second amplifier circuitry350. A third external link or connection106may be provided, coupled between the second amplifier output terminal156and the first voltage sense terminal166of the second amplifier circuitry350.

Thus, a feedback path is provided from the output node172of the second half-bridge output stage170to the first input of the second input stage160, either via the third external link or connection106(if provided) and the third feedback resistor164aor via the third shunt resistor174and the third feedback resistor164aif the third external link or connection106is not provided.

A feedback path is also provided from the second terminal of the second external load155to the second input of the second input stage160, via the fourth feedback resistor164b.

FIG.4is a schematic representation of the IC300ofFIG.3reconfigured as a differential full-bridge amplifier for driving a single load200.

As can be seen inFIG.4, in this configuration the load200is coupled between the first amplifier output terminal116and the second amplifier output terminal156, and the first input stage120provides signals to both the first half-bridge output stage130and the second half-bridge output stage170, such that the load200is driven by a differential output signal pair provided by the first and second first half-bridge output stages130,170. The second input stage160is not used.

A first external link or connection102is provided to couple the first amplifier output terminal116to the first voltage sense terminal126of the first amplifier circuitry310, thus providing a feedback path (containing the first feedback resistor124aof the first amplifier circuitry310) between the first amplifier output terminal116and the first input of the first input stage120. A fifth external link or connection202is provided to couple the second amplifier output terminal156to the second voltage sense terminal128of the first amplifier circuitry310, thus providing a feedback path (containing the second feedback resistor124bof the first amplifier circuitry310) between the second amplifier output terminal156and the second input of the first input stage120.

In this configuration the second shunt resistor136cannot form part of a feedback path between the load200and the second input of the first input stage120. Thus, if the fifth external link or connection202is broken or not provided, the first amplifier circuitry310adopts an open-loop configuration, which may lead to problems of instability and the like.

FIG.5is a schematic diagram illustrating an alternative IC implementation of amplifier circuitry configured as a differential full-bridge amplifier for driving a single load200. The IC, shown generally at500inFIG.5, includes a number of features in common with the IC100ofFIGS.1and2. Such common features are denoted by common reference numerals inFIGS.1,2and5, and will not be described again in detail here for the sake of clarity and brevity.

The IC500comprises first and second amplifier circuitry510,550that are similar to the first and second amplifier circuitry110,150described above with reference toFIG.1.

In the IC500ofFIG.5, the second shunt resistor136of the first amplifier circuitry510is not coupled to the first amplifier return terminal118of the first amplifier circuitry110.

Instead, the first amplifier circuitry110includes a dedicated shunt resistor terminal502(e.g. a pin, pad, ball or the like) to which only a first terminal of the second shunt resistor136is coupled, such that the first terminal of the second shunt resistor136is directly accessible from outside the IC500.

A second terminal of the second shunt resistor136is coupled to the second voltage sense terminal128of the first amplifier circuitry110, as in the implementation shown inFIGS.1and2.

The return path switch140(if provided) is coupled between the first amplifier return terminal118and the ground or other reference voltage supply terminal114in the same way as in the implementation shown inFIGS.1and2, and operates in the manner described above to couple the first amplifier return terminal118to the ground or other reference voltage supply terminal114in a closed state, or to decouple the first amplifier return terminal118from the ground or other reference supply terminal114in an open state.

In the differential configuration shown inFIG.5, a fifth external link or connection202is provided to couple the second amplifier output terminal156of the second amplifier circuitry550to the second voltage sense terminal128of the first amplifier circuitry510(as in the differential configuration of the IC100shown inFIG.2), to provide a feedback path between the second amplifier output terminal156and the second input of the first input stage120.

Additionally, the shunt resistor terminal502is coupled to the second amplifier output terminal156of the second amplifier circuitry550by a sixth external link or connection504.

Thus, in the implementation shown inFIG.5, in the event that the fifth external link or connection202fails or is not provided for any reason, a feedback path between the second amplifier output terminal156and the second input of the first input stage120still exists, via the sixth external link or connection504and the second shunt resistor136of the first amplifier circuitry510. Accordingly, in the differential configuration shown inFIG.5the first amplifier circuitry510always operates in a closed loop configuration.

In operation of the IC500in the differential configuration shown inFIG.5the external load200is coupled between the first amplifier output terminal116and the second amplifier output terminal156, and the first input stage120provides input signals to both the first half-bridge output stage130and the second half-bridge output stage170, such that the external load200is driven by a differential output signal pair provided by the first and second first half-bridge output stages130,170. The second input stage160is not used.

FIG.6is a schematic representation of the IC500ofFIG.5reconfigured as two separate single ended half-bridge amplifiers, each for driving a respective external load105,155.

In the configuration shown inFIG.6, a first external load105is coupled between the first amplifier output terminal116and the first amplifier return terminal118of the first amplifier circuitry510. A first external link or connection102may be provided to couple the first amplifier output terminal116to the first voltage sense terminal126of the first amplifier circuitry110, thereby providing a feedback path (containing only the first feedback resistor124a) between the first amplifier output terminal116and the first input of the first input stage120.

A second external link or connection104may be provided to couple the first amplifier return terminal118to the second voltage sense terminal128of the first amplifier circuitry110, thereby providing a feedback path (containing only the second feedback resistor124b) between the first return terminal118and the second input of the first input stage120.

A seventh external link or connection506is provided to couple the first amplifier return terminal118to the shunt resistor terminal502.

Thus, in the single ended configuration shown inFIG.6, if the first external link or connection102is not provided or fails, a feedback path containing the first shunt resistor134and the first feedback resistor124aexists between the output node132of the first half-bridge output stage130and the first input of the first input stage120. Similarly, if the second external link104or connection is not provided or fails, a feedback path containing the second shunt resistor136and the second feedback resistor124bexists between the first amplifier return terminal118and the second input of the first input stage120, via the shunt resistor terminal502.

The second amplifier circuitry550is configured in the same way as the second amplifier circuitry110described above with reference toFIG.1, with a second external load155coupled between the second amplifier output terminal156and the second amplifier return terminal158. A third external link or connection106may be provided to couple the second amplifier output terminal156to the first voltage sense terminal166of the second amplifier circuitry150. A fourth external link or connection108may be provided to couple the second return terminal158to the second voltage sense terminal168of the second amplifier circuitry550. The third and fourth shunt resistors174,176of the second amplifier circuitry550provide alternative feedback paths between the second amplifier output terminal156and the first input of the second input stage160and between the second return terminal and the second input of the second input stage160as described above with reference toFIG.1.

Thus, as will be apparent to those of ordinary skill in the art, the additional dedicated shunt resistor terminal502provided in the first amplifier circuitry510of the IC500does not affect the ability of the IC500to be configured as two single-ended half-bridge amplifiers for driving the separate loads105,155, but provides an additional feedback path that can be used to prevent open-loop operation of the first amplifier circuitry110when the IC500is configured as a differential full-bridge amplifier.

FIG.7is a schematic diagram illustrating a further alternative IC implementation of amplifier circuitry configured as a differential full-bridge amplifier for driving a single external load200. The IC, shown generally at700inFIG.7, includes a number of features in common with the IC300ofFIGS.3and4. Such common features are denoted by common reference numerals inFIGS.3,4and7, and will not be described again in detail here for the sake of clarity and brevity.

The IC700comprises first and second amplifier circuitry710,750that are similar to the first and second amplifier circuitry310,350described above with reference toFIG.3.

In the IC700ofFIG.7, the first terminal of the second shunt resistor136of the first amplifier circuitry710is not coupled to the first amplifier ground path312of the first amplifier circuitry710.

Instead, the first amplifier circuitry710includes a dedicated shunt resistor terminal702(e.g. a pin, pad, ball or the like) to which only a first terminal of the second shunt resistor136is coupled, such that the first terminal of the second shunt resistor136is directly accessible from outside the IC700.

A second terminal of the second shunt resistor136is coupled to the second voltage sense terminal128of the first amplifier circuitry710, as in the implementations shown inFIGS.1-6.

In the differential configuration shown inFIG.7, a fifth external link or connection202is provided to couple the second amplifier output terminal156of the second amplifier circuitry750to the second voltage sense terminal128of the first amplifier circuitry710(as in the differential configuration of the IC100,300,500shown inFIGS.2,4and5), to provide a feedback path between the second amplifier output terminal156and the second input of the first input stage120.

Additionally, the dedicated shunt resistor terminal702is coupled to the second amplifier output terminal156of the second amplifier circuitry750by an eighth external link or connection704.

Thus, in the implementation shown inFIG.7, in the event that the fifth external link or connection202fails or is not provided for any reason, a feedback path between the second amplifier output terminal156and the second input of the first input stage120still exists, via the eighth external link or connection704and the second shunt resistor136of the first amplifier circuitry710. Accordingly, in the differential configuration shown inFIG.7the first amplifier circuitry710always operates in a closed loop configuration.

In operation of the IC700in the differential configuration shown inFIG.7the external load200is coupled between the first amplifier output terminal116and the second amplifier output terminal156, and the first input stage120provides input signals to both the first half-bridge output stage130and the second half-bridge output stage170, such that the external load200is driven by a differential output signal pair provided by the first and second first half-bridge output stages130,170. The second input stage160is not used.

FIG.8is a schematic representation of the IC700ofFIG.7reconfigured as two separate single-ended half-bridge amplifiers, each for driving a respective load105,155.

In the configuration shown inFIG.8, a first terminal of a first external load105(e.g. a transducer such as a speaker or an actuator such as a linear resonant actuator) is coupled to the first amplifier output terminal116. A second terminal of the first external load105is coupled to the ground or other reference voltage supply terminal114of the first amplifier circuitry710. The second terminal of the first external load105is also coupled to the second voltage sense terminal128of the first amplifier circuitry710. A first external link or connection102may be provided, coupled between the first amplifier output terminal116and the first voltage sense terminal126of the first amplifier circuitry710.

Thus, a feedback path is provided from the output node132of the first half-bridge output stage130to the first input of the first input stage120, either via the first external link or connection102(if provided) and the first feedback resistor124aor via the first shunt resistor134and the first feedback resistor124aif the first external link or connection102is not provided.

A feedback path is also provided from the second terminal of the first external load105to the second input of the first input stage120, via the second feedback resistor124b.

The second amplifier circuitry750is configured in the same way as the second amplifier circuitry310described above with reference toFIG.3, with a second external load155coupled between the second amplifier output terminal156and the ground or other reference voltage supply terminal154of the second amplifier circuitry750. A third external link or connection106may be provided to couple the second amplifier output terminal156to the first voltage sense terminal166of the second amplifier circuitry750.

Thus, a feedback path is provided from the output node172of the second half-bridge output stage170to the first input of the second input stage160, either via the third external link or connection106(if provided) and the third feedback resistor164aor via the third shunt resistor174and the third feedback resistor164aif the third external link or connection106is not provided.

A feedback path is also provided from the second terminal of the second external load155to the second input of the second input stage160, via the fourth feedback resistor164b.

Thus, as will be apparent to those of ordinary skill in the art, the additional dedicated shunt resistor terminal702provided in the first amplifier circuitry710of the IC700does not affect the ability of the IC700to be configured as two single-ended half-bridge amplifiers for driving the separate loads105,155, but provides an additional feedback path that can be used to prevent open-loop operation of the first amplifier circuitry710when the IC700is configured as a differential full-bridge amplifier.

FIG.9is a schematic diagram illustrating an alternative IC implementation of amplifier circuitry configurable for driving a single ended or differential external load. In the example shown inFIG.9, the amplifier circuitry is configured as two single ended half-bridge amplifiers.

The IC, shown generally at900inFIG.9, includes a number of features in common with the IC100ofFIGS.1and2. Such common features are denoted by common reference numerals inFIGS.1,2and9, and will not be described again in detail here for the sake of clarity and brevity.

The IC900comprises first and second amplifier circuitry910,950that are similar to the first and second amplifier circuitry110,150described above with reference toFIG.1.

The IC900differs from the IC100ofFIGS.1and2in that it includes a selectable feedback path920for coupling the output node172of the second output stage170to the second input of the first input stage120, via the third shunt resistor174of the second amplifier circuitry950.

Thus, the selectable feedback path920enables the third shunt resistor174of the second amplifier circuitry150to be used as a feedback resistor when the first and second amplifier circuitry910,950are configured as a differential full-bridge amplifier for driving the load.

The selectable feedback path920includes a feedback resistor922and a first feedback path selector switch924, and is coupled, at a first end thereof, to the second input of the first input stage120. A second end of the selectable feedback path920is coupled to the first terminal of the third shunt resistor174of the second amplifier circuitry950.

The IC900further includes a second feedback path selector switch926in the second feedback path122bof the first amplifier circuitry910and a third feedback path selector switch928in the first feedback path122aof the first amplifier circuitry910.

In some examples the IC900may further include an additional dummy feedback path930for coupling the output node172of the second output stage170to the first input of the first input stage120, via the third shunt resistor174of the second amplifier circuitry950. The additional dummy feedback path930includes a dummy feedback resistor932and a dummy feedback path selector switch934.

The purpose of the additional dummy feedback path930is to balance the effect of the selectable feedback path920when the first amplifier circuitry910is configured as a single-ended half-bridge amplifier, to ensure that the impedance of the selectable feedback path920seen by the second input of the first input stage120is matched by an equivalent impedance seen by the first input of the first input stage120. To this end, the resistance of the dummy feedback resistor932is equal to the resistance of the feedback resistor922, and the characteristics of the dummy feedback path selector switch934are matched to those of the first feedback path selector switch924.

When the IC900is in its differential full-bridge amplifier configuration, the load is coupled between the first amplifier output terminal116of the first amplifier circuitry910and the first amplifier output terminal156of the second amplifier circuitry950. The first input stage120provides input signals to both the first half-bridge output stage130and the second first half-bridge output stage170, such that the load200is driven by a differential output signal pair provided by the first and second first half-bridge output stages130,170. The second input stage160is not used.

The first feedback path122ais coupled to the output node132of the output stage130of the first amplifier circuitry910, either by the first external link or connection102or, if the first external link or connection102is not provided or is broke, by the first shunt resistor132of the first amplifier circuitry910, and the third feedback path selector switch928is closed.

The first feedback path selector switch924is closed, such that the selectable feedback path920couples the output node172of the output stage170of the second amplifier circuitry950to the second input of the input stage120of the first amplifier circuitry910, either via the third external link or connection106and the feedback resistor922of the selectable feedback path920or, if the third external link or connection108is not provided or is broken, via the third shunt resistor174of the second amplifier circuitry950and the feedback resistor922of the selectable feedback path920.

The second feedback path selector switch926is opened, to decouple the second input of the first input stage120from the second feedback path122bof the first amplifier circuitry910.

Thus, in the implementation shown inFIG.9, in the event that the third external link or connection106fails or is not provided for any reason, a feedback path between the second amplifier output terminal156and the second input of the first input stage120still exists, via the third shunt resistor174of the second amplifier circuitry950. Accordingly, in the differential configuration shown inFIG.9the first amplifier circuitry910always operates in a closed loop configuration.

The IC900ofFIG.9can also be configured to provide two single-ended half-bridge amplifiers for driving separate loads. In this configuration the first feedback path selector switch924is opened and the second and third feedback path selector switches926,928are closed, such that the IC900adopts the configuration shown inFIG.9. As noted above, in this configuration the impedance of the dummy feedback path930seen at the second input of the first input stage210matches that of the selectable feedback path920seen at the first input of the first input stage210.

In the examples described above and illustrated inFIGS.1-9the first and second amplifier circuitry is described as being provided on a single IC (e.g. IC100,300,500,700,900). However it will be appreciated that in other examples the first amplifier could be provided on a first IC and the second amplifier circuitry could be provided on a second IC.

As will be apparent from the foregoing description, the circuitry of the present disclosure ensures that feedback paths are provided between the first terminal of the load200and the first input of the first input stage120and between the second terminal of the load200and the second input of the first input stage120when the first and second amplifier circuitry are used together to implement a full-bridge differential amplifier for driving a single load200, thus preventing unintended open-loop operation of the amplifier.

The circuitry described above with reference to the accompanying drawings may be incorporated in a host device such as a laptop, notebook, netbook or tablet computer, a gaming device such as a games console or a controller for a games console, a virtual reality (VR) or augmented reality (AR) device, a mobile telephone, a portable audio player or some other portable device, or may be incorporated in an accessory device for use with a laptop, notebook, netbook or tablet computer, a gaming device, a VR or AR device, a mobile telephone, a portable audio player or other portable device.