Cirrus Logic Inc.

Koninklijke Philips Corporation N.v.

Other

Philips Lighting Holding B.v.

Signify Holding B.v.

Zhaohui He

John L Melanson

Eric Jerome King

Siddharth Maru

Rahul Singh

Michael Allan Kost

Mohit Sood

Ruoxin Jiang

Robert Thomas Grisamore

William Draper

Lingli Zhang

Yanhui Xie

Chris Michael Franklin

Tejasvi Das

Emmanuel A Marchais

Paul M Astrachan

Prashanth Drakshapalli

Thomas H Hoff

Kyehyung Lee

Mauro L Gaetano

Yongjie Cheng

Spencer Isaacson

This application relates to methods and apparatus for driving a transducer. A transducer driver has a switch network that is operable to selectively connect a driver output to any of a first set of at least three different switching voltages which are, in use, maintained throughout a switching cycle of the driver apparatus. The switch network is also operable to selectively connect the driver output to flying capacitor driver. A controller is configured to control the switch network and flying capacitor driver to generate a drive signal at the driver output based on an input signal, wherein in one mode of operation the driver output is switched between two of the first set of switching voltages with a controlled duty cycle and in another mode of operation the driver output is connected to the flying capacitor driver which is switched between first and second states with a controlled duty cycle.

Driver circuitry and operation

A Class-D amplifier that includes a driver stage operable in a plurality of modes having different respective output impedances, a loop filter having an output, and a circuit configured to sense a current at a load of the Class-D amplifier, determine, based on the sensed current, an IR drop for a respective output impedance of the driver stage, and add the IR drop to the loop filter output to compensate for the respective output impedance of the driver stage to reduce distortion.

Distortion reducing variable output impedance class-D amplifier

A Class-D amplifier includes a plurality of power rails, a quantizer, and a driver stage. The quantizer and the driver stage have a combined gain. For each power rail of the plurality of power rails, the Class-D amplifier senses a voltage value for the power rail and determines a ramp amplitude based on the sensed voltage value. The Class-D amplifier concurrently switches from the driver stage using a first power rail to a second power rail of the plurality of power rails and switches from the quantizer using the ramp amplitude associated with the first power rail to using the ramp amplitude associated with the second power rail so that the combined gain is constant.

Class-D amplifier with multiple power rails and quantizer that switches used ramp amplitude concurrently with switch in used power rail

A Class-D amplifier having a low power dissipation mode includes first and second independent output stages that receive respective first and second level power supply voltages for driving a load coupled to the amplifier output during respective first and second operating modes. Bypass switches are controllable to disconnect the second output stage from the output during the first operating mode and to connect the second output stage to the output during the second operating mode. The operating modes are selected based on the amplifier output power level. First and second independent pre-driver stages receive the respective first and second level power supply voltages for driving the respective first and second independent output stages. During the second operating mode the first pre-driver stage is placed into a low power dissipation state and during the first operating mode the second pre-driver stage is placed into a low power dissipation state.

Class-D amplifier with multiple independent output stages

In a Class-D amplifier, first/second ratios and first/second RC time constants are sequentially matched by trimming. An integrator is coupled to differential first/second paths. The first/second ratios are of a feedback resistor to an input resistor in the first/second paths. R's of the first/second RC time constants are the resistors of the first/second matched ratios. C's of the first/second RC time constants are integrating capacitors in the first/second path. For each of multiple power rails, a ramp amplitude is determined based on a sensed voltage. Concurrently, the driver stage is switched from first to second power rails and quantizer switched from first to second ramp amplitudes to achieve constant combined quantizer/driver stage gain. Based on a sensed load current, an IR drop is determined for a respective output impedance of the driver stage and added to a loop filter output to compensate for the respective output impedance.

Low power dissipation high performance Class-D amplifier

A class-D amplifier system includes one or more pulse width modulation (PWM) output paths at least one of which includes one or more digital closed-loop PWM modulators (DCL-PWMM) in which at least one of the DCL_PWMM includes a digital integrator that provides an output value and receives a feedback value. The output value has an output resolution and the feedback value has a feedback resolution that is coarser than the output resolution. The output value is the sum of an integer multiple of the feedback resolution and a residue. Control logic decreases/increases the residue of the digital integrator toward an integer multiple of the feedback resolution over a plurality of clock cycles in response to a request to transition the class-D amplifier and forces an output of the DCL_PWMM to have an approximate 50% duty cycle after decreasing/increasing the residue over the plurality of clock cycles.

Apparatus and method of suppressing transient noise during transition for class-D amplifier system having one or more pulse width modulator output paths

A signal processing system for producing a load voltage at a load output of the signal processing system, wherein the load output comprises a first load terminal having a first load voltage and a second load terminal having a second load voltage such that the load voltage comprises a difference between the first load voltage and the second load voltage, and may include a first processing path configured to process a first signal derived from an input signal to generate the first load voltage at a first processing path output, a second processing path configured to process a second signal received at a second processing path input and derived from the input signal, wherein the second signal comprises information of the input signal absent from the first signal, to generate the second load voltage at a second processing path output, and a high-pass filter coupled between the first processing path output and the second processing path input.

Removal of switching discontinuity in a hybrid switched mode amplifier

A switching power stage for producing a load voltage at a load output of the switching power stage, wherein the load output comprises a first load terminal having a first load voltage and a second load terminal having a second load voltage such that the load voltage comprises a difference between the first and the second load voltages, that may include: a power converter comprising a power inductor and a plurality of switches, wherein the power converter is configured to drive a power converter output terminal; a linear amplifier configured to drive a linear amplifier output terminal; and a controller for controlling the plurality of switches and the linear amplifier in order to generate the load voltage as a function of an input signal to the controller such that energy delivered to the load output is supplied predominantly by the power converter.

Switched mode converter with variable common mode voltage buffer

A method may include processing a first signal derived from an input signal with a first path to generate a first path voltage at a first path output, processing a second signal derived from the input signal with a second path to generate a second path voltage at a second path output, the second path comprising a linear amplifier having at least one transistor for driving the second path voltage, generating the first signal and the second signal with a signal splitter, such that the second signal comprises information of the input signal absent from the first signal, and such that the second path voltage is of a sufficient magnitude such that the at least one transistor operates in a saturation region of the at least one transistor throughout a dynamic range of a load voltage equal to the difference of the first path voltage and the second path voltage.

Generation of voltage reference signals in a hybrid switched mode amplifier

A method may include controlling switches of a switching full-bridge of a signal processing system to commutate polarity of a capacitor with respect to the first processing path output and a second processing path output of the signal processing system in response to a condition for commutating connectivity of the switching full-bridge and inserting a feedforward compensation that bypasses a loop filter of the second processing path in order to prevent discontinuities caused by commutating polarity of the capacitor from being compensated by the loop filter.

Prevention of switching discontinuity in a hybrid switched mode amplifier

A switching power stage for producing a load voltage may include a first processing path having a first output, a second processing path having a second output, a first plurality of switches comprising at least a first switch coupled between the first output and a first load terminal and a second switch coupled between the first output and the second load terminal, a second plurality of switches comprising at least a third switch coupled between the second output and the first load terminal and a fourth switch coupled between the second output and the second load terminal, and a controller configured to control switches in order to generate the load voltage as a function of an input signal such that one of the first switch and the second switch operates in a linear region of operation and one of the third switch and the fourth switch operates in a saturated region of operation for a predominance of a dynamic rage of the load voltage.

Hybrid switched mode amplifier

A power distribution system includes controller of a switching power converter to control the switching power converter and determine one or more switching power converter control parameters. In at least one embodiment, the switching power converter utilizes a transformer to transfer energy from a primary-side of the transformer to a secondary-side of the transformer. In at least one embodiment, the switching power converter control parameters includes a secondary-side conduction time delay that represents a time delay between when the primary-side ceases conducting a primary-side current and the secondary-side begins to conduct a secondary-side current. In at least one embodiment, determining and accounting for this secondary-side conduction time delay increases the prediction accuracy of the secondary-side current value and accurate delivery of energy to a load when the controller does not directly sense the secondary-side current provided to the load.

Utilizing secondary-side conduction time parameters of a switching power converter to provide energy to a load

An electronic system and method include a controller to operate in a start-up mode to accelerate driving a load to an operating voltage and then operates in a post-start-up mode. A start-up condition occurs when the controller detects that a load voltage is below a predetermined voltage threshold level. The predetermined voltage threshold level is set so that the controller will boost the voltage to an operating value of a load voltage at a faster rate than during normal, steady-state operation. The controller causes a switching power converter to provide charge to the load at a rate in accordance with a start-up mode until reaching an energy-indicating threshold. When the energy-indicating threshold has been reached, the controller causes the switching power converter to (i) decrease the amount of charge provided to the load relative to the charge provided during the start-up mode and (ii) operate in a distinct post-start-up-mode.

Acceleration of output energy provision for a load during start-up of a switching power converter

A power control system provides immunity from power supply dropout for a controller without compromising a startup time of the controller. In at least one embodiment, the power control system includes separate startup and dropout immunity capacitors. In at least one embodiment, selection of the capacitance of the startup capacitor is independent of selection of the capacitance of the dropout immunity capacitance. In at least one embodiment, the startup capacitance can be minimized to provide sufficient energy for the controller to normally operate during one missed cycle of an input voltage and, thus, provide a minimum startup time for the controller. The capacitance of the dropout immunity capacitor can be maximized to provide sufficient energy for the controller to operate normally during a time period longer than one cycle of the input voltage.

Power control system with power drop out immunity and uncompromised startup time

An electronic system includes a controller to provide at least dual-mode conduction control of a switching power converter. In at least one embodiment, the controller is capable to control transitions between discontinuous conduction mode (DCM) and critical conduction mode (CRM) of the switching power converter using a measured switching time parameter having a value corresponding with an approximately peak voltage of a time-varying supply voltage supplied to the switching power converter. In at least one embodiment, the controller dynamically compensates for changing parameters of the electronic system by dynamically determining a minimum non-conductive time of the control switch of the switching power converter using the measured switching time parameter value at approximately the peak of the supply voltage of the supply voltage.

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Austin, TX, United States of America

Zhaohui He