Versatile audio power amplifier

• US 8,922,278 B2
• Filed: 09/09/2013
• Issued: 12/30/2014
• Est. Priority Date: 03/04/2010
• Status: Active Grant

• Current Assignee: Bose Corporation
• Original Assignee: Bose Corporation
• Inventors: Nussbaum, Michael, Sheen, Timothy, Pearce, Daniel Scott
• Primary Examiner(s): Nguyen, Khanh V
• Application Number:
  US14/021,434
• Publication Number:
  US 20140009230A1
• Time in Patent Office: 477 Days
• Field of Search: 330/10, 330/207.A, 330/251
• US Class Current: 330/251
• CPC Class Codes: H03F 1/0205 in transistor amplifiers
• CPC Class Codes: H03F 2200/03 the amplifier being designed for audio applications
• CPC Class Codes: H03F 2203/21 with semiconductor devices only
• CPC Class Codes: H03F 3/185 with field-effect devices H03F3/187 takes precedence
• CPC Class Codes: H03F 3/217 Class D power amplifiers; Switching amplifiers
• CPC Class Codes: H03F 3/2171 with field-effect devices H03F3/2173 - H03F3/2178 take precedence
• CPC Class Codes: H03F 3/2173 of the bridge type
• CPC Class Codes: H03F 3/2178 using more than one switch or switching amplifier in parallel or in series H03F3/2173, H03F3/2175 take precedence
• CPC Class Codes: H03F 3/68 Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics power amplifiers using a combination of several semiconductor amplifiers H03F3/211; combinations of amplifiers using coupling networks with distributed constants H03F3/602

Abstract

An audio power amplifier includes a first and a second amplification unit, each including a switching voltage amplifier, an output filter, a current compensator, an inner current feedback loop feeding a measurement of current measured at the output inductor back to a summing input of the current compensator, a voltage compensator coupled to the summing input of the current compensator, and an outer voltage feedback loop. A controlled signal path provides the output of the voltage compensator of the first amplification unit to the current compensator of the second amplification unit. The first and second amplification units are operable with separate loads, in parallel driving a common load, or across a bridge-tied-load. A second pair of amplification units may be added and operated together with the first pair to drive a single speaker with a parallel pair of amplifiers on each side of a bridge-tied-load.

Claims

1. An audio power amplifier comprising:

a four-quadrant power supply having a synchronous output rectifier;

a first amplification unit and a second amplification unit, each amplification unit comprising;

a switching voltage amplifier having a command signal input and an amplified signal output,

an output filter between the amplified signal output and a load terminal,

a current compensator with a current-compensated command signal output coupled to the command signal input of the switching voltage amplifier,

an inner current feedback loop feeding a measurement of current measured at the output filter back to a summing input of the current compensator,

a voltage compensator with a voltage-compensated command signal output coupled to the summing input of the current compensator, and

an outer voltage feedback loop feeding voltage at the load terminal back to a summing input of the voltage compensator; and

control electronics providing signal inputs to the first and second amplification units and controlling the first and second amplification units such that the first and second amplification units are operable with separate loads, in parallel driving a common load, or across a bridge-tied-load.

2. The audio power amplifier of claim 1 wherein the first and second amplification units are operable with separate loads by each amplifying separate signals and providing the amplified signals on their separate output terminals.

3. The audio power amplifier of claim 1 wherein the first and second amplification units are operable in parallel driving a common load by each amplifying the same signal and providing substantially identical amplified signals on their separate output terminals, which are to be coupled to a common input terminal of the common load.

4. The audio power amplifier of claim 1 wherein the first and second amplification units are operable across a bridge-tied-load by amplifying a first signal in the first amplification unit and amplifying an inverse of the first signal in the second amplification unit, and providing their respective amplified signals on their separate output terminals, which are to be coupled to separate input terminals of the load.

5. The audio power amplifier of claim 1 further comprising:

a third and a fourth amplification unit substantially identical to the first and second amplification units,

the control electronics further providing signal inputs to the third and fourth amplification units and controlling the third and fourth amplification units such that the third and fourth amplification units are operable with separate loads, in parallel driving a common load, or across a bridge-tied-load, and

all four of the amplification units are operable together with the first and second amplification units in parallel driving a first side of a bridge-tied-load, and the third and fourth amplification units in parallel driving a second side of the bridge-tied-load.

6. The audio power amplifier of claim 5 wherein the four amplification units are operable together by:

amplifying a first signal in each of the first and second amplification units and providing substantially identical amplified first signals on separate output terminals of the first amplification unit and the second amplification unit,

amplifying an inverse of the first signal in each of the third and fourth amplification units and providing substantially identical amplified inverted first signals on separate output terminals of the third amplification unit and the fourth amplification unit,

wherein the output terminals of the first and second amplification units are coupled to a first input of the load, and the output terminals of the third and fourth amplification units are coupled to a second input of the load.

7. The audio power amplifier of claim 1 wherein the synchronous output rectifier comprises a MOSFET.

8. The audio power amplifier of claim 1 further comprising:

a first controlled signal path from the voltage-compensated command signal output of the voltage compensator of the first amplification unit to the summing input of the current compensator of the second amplification unit,

the second amplification unit configured to use the voltage-compensated command signal of the first amplification unit as input to the current compensator of the second amplification unit in place of the voltage-compensated command signal of the second amplification unit when the first controlled signal path is activated.

9. The audio power amplifier of claim 8 wherein the first controlled signal path comprises a switch controlled by the control electronics.

10. The audio power amplifier of claim 1 wherein the switching voltage amplifiers each comprise a modulator, a gate driver, a pair of transistors, and a pair of diodes coupled between the source and drain terminals of the transistors.

11. The audio power amplifier of claim 10 wherein the transistors comprise MOSFETS, the diodes being intrinsic to the MOSFETS.

12. The audio power amplifier of claim 1 wherein the output filter comprises an output inductor and the measured current is the current through the output inductor.

13. An audio power amplifier comprising:

a first, a second, a third, and a fourth amplification unit, each amplification unit comprising;

a switching voltage amplifier having a command signal input and an amplified signal output,

an output filter between the amplified signal output and a load terminal,

a current compensator with a current-compensated command signal output coupled to the command signal input of the switching voltage amplifier,

an inner current feedback loop feeding a measurement of current measured at the output filter back to a summing input of the current compensator,

a voltage compensator with a voltage-compensated command signal output coupled to the summing input of the current compensator, and

an outer voltage feedback loop feeding voltage at the load terminal back to a summing input of the voltage compensator; and

control electronics providing signal inputs to the first and second amplification units and controlling the first and second amplification units such that the first and second amplification units are operable with separate loads, in parallel driving a common load, or across a bridge-tied-load,

the control electronics further providing signal inputs to the third and fourth amplification units such that the third and fourth amplification units are operable with separate loads, in parallel driving a common load, or across a bridge-tied-load, and

all four of the amplification units are operable together with the first and second amplification units in parallel driving a first side of a bridge-tied-load, and the third and fourth amplification units in parallel driving a second side of the bridge-tied-load.

14. The audio power amplifier of claim 13 wherein the four amplification units are operable together by:

amplifying a first signal in each of the first and second amplification units and providing substantially identical amplified first signals on separate output terminals of the first amplification unit and the second amplification unit,

amplifying an inverse of the first signal in each of the third and fourth amplification units and providing substantially identical amplified inverted first signals on separate output terminals of the third amplification unit and the fourth amplification unit,

wherein the output terminals of the first and second amplification units are coupled to a first input of the load, and the output terminals of the third and fourth amplification units are coupled to a second input of the load.

15. The audio power amplifier of claim 13 further comprising:

a first controlled signal path from the voltage-compensated command signal output of the voltage compensator of the first amplification unit to the summing input of the current compensator of the second amplification unit,

the second amplification unit configured to use the voltage-compensated command signal of the first amplification unit as input to the current compensator of the second amplification unit in place of the voltage-compensated command signal of the second amplification unit when the first controlled signal path is activated; and

a second controlled signal path from the voltage-compensated command signal output of the voltage compensator of the third amplification unit to the summing input of the current compensator of the fourth amplification unit,

the fourth amplification unit configured to use the voltage-compensated command signal of the third amplification unit as input to the current compensator of the fourth amplification unit in place of the voltage-compensated command signal of the fourth amplification unit when the second controlled signal path is activated.

16. The audio power amplifier of claim 15 wherein the first controlled signal path and the second controlled signal path comprise a switch controlled by the control electronics.

17. The audio power amplifier of claim 13 wherein the switching voltage amplifiers each comprise a modulator, a gate driver, a pair of transistors, and a pair of diodes coupled between the source and drain terminals of the transistors.

18. The audio power amplifier of claim 17 wherein the transistors comprise MOSFETS, the diodes being intrinsic to the MOSFETS.

19. The audio power amplifier of claim 13 wherein the output filter comprises an output inductor and the measured current is the current through the output inductor.

20. An audio power amplifier comprising:

a first, a second, a third, and a fourth amplification unit, each amplification unit comprising;

a switching voltage amplifier having a command signal input and an amplified signal output,

an output filter between the amplified signal output and a load terminal,

a current compensator with a current-compensated command signal output coupled to the command signal input of the switching voltage amplifier,

an inner current feedback loop feeding a measurement of current measured at the output filter back to a summing input of the current compensator,

a voltage compensator with a voltage-compensated command signal output coupled to the summing input of the current compensator, and

an outer voltage feedback loop feeding voltage at the load terminal back to a summing input of the voltage compensator;

a four-quadrant power supply having a synchronous output rectifier, the power supply providing power to the first, second, third and fourth amplification units; and

control electronics providing signal inputs to the first and second amplification units and controlling the first and second amplification units such that the first and second amplification units are operable with separate loads, in parallel driving a common load, or across a bridge-tied-load,

the control electronics further providing signal inputs to the third and fourth amplification units such that the third and fourth amplification units are operable with separate loads, in parallel driving a common load, or across a bridge-tied-load, and

all four of the amplification units are operable together with the first and second amplification units in parallel driving a first side of a bridge-tied- load, and the third and fourth amplification units in parallel driving a second side of the bridge-tied-load.

21. The audio power amplifier of claim 20 wherein the four amplification units are operable together by:

amplifying a first signal in each of the first and second amplification units and providing substantially identical amplified first signals on separate output terminals of the first amplification unit and the second amplification unit,

amplifying an inverse of the first signal in each of the third and fourth amplification units and providing substantially identical amplified inverted first signals on separate output terminals of the third amplification unit and the fourth amplification unit,

wherein the output terminals of the first and second amplification units are coupled to a first input of the load, and the output terminals of the third and fourth amplification units are coupled to a second input of the load.

22. The audio power amplifier of claim 20 further comprising:

a first controlled signal path from the voltage-compensated command signal output of the voltage compensator of the first amplification unit to the summing input of the current compensator of the second amplification unit,

the second amplification unit configured to use the voltage-compensated command signal of the first amplification unit as input to the current compensator of the second amplification unit in place of the voltage-compensated command signal of the second amplification unit when the first controlled signal path is activated; and

a second controlled signal path from the voltage-compensated command signal output of the voltage compensator of the third amplification unit to the summing input of the current compensator of the fourth amplification unit,

the fourth amplification unit configured to use the voltage-compensated command signal of the third amplification unit as input to the current compensator of the fourth amplification unit in place of the voltage-compensated command signal of the fourth amplification unit when the second controlled signal path is activated.

23. The audio power amplifier of claim 22 wherein the first controlled signal path and the second controlled signal path comprise a switch controlled by the control electronics.

24. The audio power amplifier of claim 20 wherein the switching voltage amplifiers each comprise a modulator, a gate driver, a pair of transistors, and a pair of diodes coupled between the source and drain terminals of the transistors.

25. The audio power amplifier of claim 24 wherein the transistors comprise MOSFETS, the diodes being intrinsic to the MOSFETS.

26. The audio power amplifier of claim 20 wherein the output filter comprises an output inductor and the measured current is the current through the output inductor.

27. The audio power amplifier of claim 20 wherein the synchronous output rectifier comprises a MOSFET.

28. An audio power amplifier comprising:

a four-quadrant power supply having a synchronous output rectifier;

a first, a second, a third and a fourth amplification unit, each amplification unit comprising;

a switching voltage amplifier having a command signal input and an amplified signal output; and

control electronics providing signal inputs to each of the amplification units and controlling the first, second, third and fourth amplification units such that;

the first and second amplification units are operable with separate loads, in parallel driving a common load, or across a bridge-tied-load,

the third and fourth amplification units are operable with separate loads, in parallel driving a common load, or across a bridge-tied-load, and

all four of the amplification units are operable together with the first and second units in parallel driving a first side of a bridge-tied-load, and the third and fourth units in parallel driving a second side of the bridge-tied-load.

29. The audio power amplifier of claim 28 wherein the four amplification units are operable together by:

amplifying a first signal in each of the first and second amplification units and providing substantially identical amplified first signals on separate output terminals of the first amplification unit and the second amplification unit,

amplifying an inverse of the first signal in each of the third and fourth amplification units and providing substantially identical amplified inverted first signals on separate output terminals of the third amplification unit and the fourth amplification unit,

wherein the output terminals of the first and second amplification units are coupled to a first input of the load, and the output terminals of the third and fourth amplification units are coupled to a second input of the load.

30. The audio power amplifier of claim 28 wherein the switching voltage amplifiers each comprise a modulator, a gate driver, a pair of transistors, and a pair of diodes coupled between the source and drain terminals of the transistors.

31. The audio power amplifier of claim 30 wherein the transistors comprise MOSFETS, the diodes being intrinsic to the MOSFETS.

32. The audio power amplifier of claim 28 wherein the synchronous output rectifier comprises a MOSFET.