Switching amplifier circuitry

Patent metadata

Field	Value
Publication number	US-12445098-B2
Application number	US-202217885719-A
Country	US
Kind code	B2
Filing date	Aug 11, 2022
Priority date	Aug 11, 2022
Publication date	Oct 14, 2025
Grant date	Oct 14, 2025

Abstract

Switching amplifier circuitry for driving an inductive load, the switching amplifier circuitry comprising modulator circuitry and output stage circuitry, wherein the switching amplifier circuitry is configured to: while the modulator circuitry is outputting a modulated output signal that gives rise to ripple current in the load: adjust a switching frequency of the modulator circuitry over a predetermined range of frequencies; monitor a power of the switching amplifier circuitry as the switching frequency is adjusted over the predetermined range of frequencies; and select, as an operational switching frequency for the modulator circuitry, a frequency within the predetermined range of frequencies at which the monitored power meets a predefined criterion.

First claim

The invention claimed is:

1. Switching amplifier circuitry for driving a load, the switching amplifier circuitry comprising:
modulator circuitry; and
output stage circuitry, wherein the switching amplifier circuitry is configured to:
while the modulator circuitry is outputting a modulated output signal that gives rise to ripple current in the load:
adjust a switching frequency of the modulator circuitry over a predetermined range of frequencies;
monitor an input power to the switching amplifier circuitry as the switching frequency is adjusted over the predetermined range of frequencies; and
select, as an operational switching frequency for the modulator circuitry, a frequency within the predetermined range of frequencies at which the monitored input power meets a predefined criterion.

2. The switching amplifier circuitry according to claim 1 , wherein:
the switching amplifier circuitry further comprises input power monitoring circuitry for monitoring the input power,
and wherein the switching amplifier circuitry is configured to select, as the operational switching frequency, a frequency within the predetermined range of frequencies at which a minimum monitored input power to the switching amplifier circuitry occurs.

3. The switching amplifier circuitry according to claim 2 , wherein the input power monitoring circuitry comprises input current monitor circuitry for monitoring an input current to the switching amplifier circuitry.

4. The switching amplifier circuitry according to claim 3 , wherein the input power monitoring circuitry further comprises input voltage monitor circuitry for monitoring an input voltage to the switching amplifier circuitry.

5. The switching amplifier circuitry according to claim 1 , wherein the modulator circuitry comprises Class D modulator circuitry operable in a Class BD operating mode or a Class AD operating mode.

6. The switching amplifier circuitry according to claim 5 , wherein the output stage circuitry comprises single ended output stage circuitry, and wherein the modulator circuitry is operable in its Class AD operating mode or its Class BD operating mode to output the modulated output signal that gives rise to ripple current in the load.

7. The switching amplifier circuitry according to claim 5 , wherein the output stage circuitry comprises differential output stage circuitry, and wherein the modulator circuitry is operable in its class AD operating mode to output the modulated output signal that gives rise to ripple current in the load.

8. The switching amplifier circuitry according to claim 5 , wherein:
the switching amplifier circuitry further comprises pilot or test signal generator circuitry operable to supply a pilot or test signal to an input of the modulator circuitry;
the output stage circuitry comprises differential output stage circuitry; and
the modulator circuitry is operable in its Class BD operating mode to output a modulated output signal that gives rise to ripple current in the load based on the pilot or test signal.

9. The switching amplifier circuitry according to claim 8 , wherein the pilot or test signal comprises:
a sinusoidal signal having predefined amplitude and/or frequency and/or phase characteristics;
a variable amplitude sinusoidal signal; or
a DC signal of fixed or variable amplitude.

10. The switching amplifier circuitry according to claim 1 , wherein the switching amplifier circuitry is configured to have zero PWM switching at idle, wherein the switching amplifier circuitry further comprises pilot or test signal generator circuitry operable to supply a pilot or test signal to an input of the modulator circuitry, and wherein the modulator circuitry is operable to output a modulated output signal that gives rise to ripple current in the load based on the pilot or test signal.

11. The switching amplifier circuitry according to claim 1 , wherein the switching amplifier circuitry is configured to have zero PWM switching at idle, wherein the switching amplifier circuitry comprises multi-mode modulator circuitry, and wherein the multi-mode modulator circuitry is operable to change its operating mode so as to output a modulated output signal that gives rise to ripple current in the load when no input signal is present.

12. The switching amplifier circuitry according to claim 1 , wherein:
the monitored input power comprises an output power of the switching amplifier circuitry;
the switching amplifier circuitry further comprises load ripple current power monitoring circuitry for monitoring the output power; and,
the switching amplifier circuitry is configured to select, as the operational switching frequency, a frequency within the predetermined range of frequencies at which a minimum monitored output power of the switching amplifier circuitry occurs.

13. The switching amplifier circuitry according to claim 12 , wherein the load ripple current power monitoring circuitry comprises load current monitor circuitry and load voltage monitor circuitry.

14. The switching amplifier circuitry according to claim 5 , wherein the switching amplifier circuitry is operable to change the operating mode of the modulator circuitry based on a characteristic or parameter of an input signal to the switching amplifier circuitry, and wherein the operational switching frequency is selected based at least in part on an average input power over time for the Class AD operating mode and the Class BD operating mode.

15. The switching amplifier circuitry according to claim 5 , wherein:
the switching amplifier circuitry is operable to change the operating mode of the modulator circuitry based on a characteristic or parameter of an input signal to the switching amplifier, and wherein the switching amplifier circuitry is configured to adjust the operational switching frequency based on a current or future operating mode of the modulator circuitry.

16. The switching amplifier circuitry according to claim 1 , wherein a modulation index of the modulated output signal is variable.

17. The switching amplifier circuitry according to claim 2 , wherein the switching amplifier circuitry further comprises load impedance detector circuitry configured to detect an impedance of the load, wherein the switching amplifier circuitry is operable to adjust the operational switching frequency based on a difference between the detected impedance of the load and a reference impedance for the load.

18. The switching amplifier circuitry according to claim 17 , wherein the reference impedance for the load comprises a stored predefined impedance value or a stored calibration impedance value determined during a calibration of the switching amplifier circuitry.

19. The switching amplifier circuitry according to claim 17 , wherein the load impedance detector circuitry is configured to detect the impedance of the load based on a voltage across the load and a current through the load as a pilot or test signal of a predetermined frequency is input to the modulator circuitry.

20. The switching amplifier circuitry according to claim 2 , wherein the switching amplifier circuitry receives a supply voltage from a power source external to the switching amplifier circuitry, wherein the supply voltage is adjustable based on a detected impedance of the load.

21. The switching amplifier circuitry according to claim 1 , wherein the switching amplifier circuitry is configured to adjust the switching frequency of the modulator circuitry:
during a production process of the switching amplifier circ

Assignees

• Cirrus Logic Int Semiconductor Ltd
• Cirrus Logic Inc

Inventors

• Beardsworth Matthew
• Melanson John L

Classifications

• H03F2200/351

  Pulse width modulation being used in an amplifying circuit · CPC title

• H03F2200/462

  the current being sensed · CPC title

• H03F2200/459

  Ripple reduction circuitry being used in an amplifying circuit · CPC title

• H03F2200/471

  the voltage being sensed · CPC title

• H03F1/0233

  by using a signal derived from the output signal, e.g. bootstrapping the voltage supply · CPC title