Switchless high efficiency amplifier

• US 6,300,828 B1
• Filed: 01/20/2000
• Issued: 10/09/2001
• Est. Priority Date: 01/20/2000
• Status: Expired due to Fees

• Current Assignee: Next Level Communications, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Next Level Communications
• Inventors: McInnis, A. J.
• Primary Examiner(s): Mottola, Steven J.
• Application Number:
  US09/488,276
• Time in Patent Office: 628 Days
• Field of Search: 330/124.R, 330/129, 330/165, 330/195, 330/51
• US Class Current: 330/124.00R
• CPC Class Codes: H03F 1/0277 Selecting one or more amplifiers from a plurality of amplifiers
• CPC Class Codes: H03F 3/211 using a combination of several amplifiers H03F3/60 takes precedence

Abstract

A high potential/high efficiency amplifier contains at least two separate amplifiers. One amplifier is used for the typical inputs that are received from an input source and a second amplifier is used solely for peak inputs. Utilizing the second amplifier to handle the peak inputs allows the first amplifier to concentrate solely on the typical inputs. A small resistor tied to the output of the second amplifier reduces the output of the second amplifier. Thus, when the output of the first and second amplifiers are equal, the output of the first amplifier will be applied to the load. When the input exceeds the operational value for the first amplifier, the first amplifier logically disconnects itself from the load and the output of the second amplifier is applied to the load. Once the input returns to a value within the limits of the first amplifier, the first amplifier becomes operational again, and the resistor again becomes a barrier to the second output being applied to the load.

Claims

1. A switchless high efficiency amplifier comprising:

a load;

a first input supply;

a first amplifier having a first input connected to the first input supply, a first output connected to a first end of the load, and a first gain defined by a first negative feedback loop;

a second amplifier having a second input connected to the input supply, a second output connected to a first end of the load via a first resistive element, and a second gain defined by a second negative feedback loop, wherein when the first output and the second output are the same, the first resistive element reduces the second output so that the first output is greater and is therefore provided to the load, further wherein the first gain and the second gain are equal so that the first output and the second output are equal; and

a first operational voltage applied to the first amplifier and a second operational voltage greater than the first operational voltage applied to the second amplifier.

2. The switchless high efficiency amplifier of claim 1, wherein the first amplifier can produce the first output up to of the first operational voltage and the second amplifier can produce the second output up to of the second operational voltage.

3. The switchless high efficiency amplifier of claim 1, wherein the first amplifier and the second amplifier do not allow reverse current flow.

4. The switchless high efficiency amplifier of claim 2, wherein when the input supply supplies an input that would produce the first output above the first operational voltage, the first amplifier becomes reverse biased and logically disconnects from the load.

5. The switchless high efficiency amplifier of claim 4, wherein the second amplifier provides the second output to the load when the first amplifier is logically disconnected from the load.

6. The switchless high efficiency amplifier of claim 1, wherein the first resistive element prevents the second amplifier from supplying current inefficiently to the load while the first amplifier is capable of producing the first output in response to an input from the input supply.

7. The switchless high efficiency amplifier of claim 6, wherein the first resistive element provides little impediment to current flow from the second output to the load, when the first amplifier is logically disconnected from the load.

8. The switchless high efficiency amplifier of claim 1, wherein the second gain is reduced by the first resistive element.

9. The switchless high efficiency amplifier of claim 1, wherein the first resistive element is small in comparison to the load.

10. The switchless high efficiency amplifier of claim 1, further comprising:

a second input supply;

a third amplifier having a third input connected to the second input supply, a third output connected to a second end of the load, and a third gain defined by a third negative feedback loop;

a fourth amplifier having a fourth input connected to the second input supply, a fourth output connected to the second end of the load via a second resistive element, and a fourth gain defined by a fourth negative feedback loop, wherein when the third output and the fourth output are the same, the second resistive element reduces an absolute value of the fourth output so that an absolute value of the third output is greater and is therefore applied to the second end of the load; and

a third operational voltage applied to the third amplifier, and a fourth operational voltage having an absolute value greater than the absolute value of the third operational voltage applied to the fourth amplifier.

11. The switchless high efficiency amplifier of claim 10, wherein the first gain, the second gain, the third gain and the fourth gain are equal so that the first output and the second output are equal and the third output and the fourth output are equal.

12. The switchless high efficiency amplifier of claim 10, wherein when the second input supply supplies an input that would produce the third output above the third operational voltage, the third amplifier becomes reverse biased and logically disconnects from the load.

13. The switchless high efficiency amplifier of claim 1, further compromising

a first transformer winding having a first number of windings connected to the first output;

a second transformer winding having a second number of windings connected to the first resistive element; and

a third transformer winding connected to the load.

14. The switchless high efficiency amplifier of claim 13, further compromising an operational voltage applied to the first amplifier and the second amplifier.

15. The switchless high efficiency amplifier of claim 14, wherein a ratio of the first gain to the second gain is equal to a ratio of the first number of winding to the second number of windings.

16. A switchless high efficiency amplifier comprising:

a first parallel path including a first voltage amplifier defined by a first gain;

a second parallel path including a second voltage amplifier defined by a second gain, and a first resistor in series with the second voltage amplifier, wherein the second voltage amplifier has a higher operating voltage than the first voltage amplifier;

a first voltage supply providing a first supply voltage to the first parallel path and the second parallel path, wherein the first parallel path will have a first output voltage and the second parallel path will have a second output voltage;

a load having a first end connected to the first output voltage and the second output voltage, and a second end connected to a reference voltage, wherein current will flow through the load from the greater of the first output voltage and the second output voltage to the reference voltage.

17. The switchless high efficiency amplifier of claim 16, wherein the first gain and the second gain are the same.

18. The switchless high efficiency amplifier of claim 17, wherein the first resistor reduces the second gain so that the first output voltage is greater than the second output voltage.

20. The switchless high efficiency amplifier of claim 16, further comprising:

a third parallel path including a third voltage amplifier defined by the first gain;

a fourth parallel path including a fourth voltage amplifier defined by the second gain, and a second resistor in series with the fourth voltage amplifier, wherein the third voltage amplifier and the fourth voltage amplifier are positive voltage amplifiers and the fourth voltage amplifier has a higher operating voltage than the third voltage amplifier; and

a second voltage supply providing a second supply voltage to the third parallel path and the fourth parallel path, wherein the third parallel path will have a third output voltage and the fourth parallel path will have a fourth output voltage and the reference voltage is the lessor of the third output voltage and the fourth output voltage.

21. The switchless high efficiency amplifier of claim 20, wherein the first gain and the second gain are the same.

22. The switchless high efficiency amplifier of claim 20, wherein the third voltage amplifier and the fourth voltage amplifier are negative voltage amplifiers and the fourth voltage amplifier has a higher absolute operating voltage than the third voltage amplifier.

23. The switchless high efficiency amplifier of claim 20, wherein the absolute operating voltages of the first voltage amplifier and the third voltage amplifier are the same and the absolute operating voltages of the second voltage amplifier and the fourth voltage amplifier are the same and are higher than the absolute operating voltages of the first voltage amplifier and the third voltage amplifier.

24. The switchless high efficiency amplifier of claim 16, wherein the first parallel path further includes a first transformer winding having a first number of windings and the second parallel path further includes a second transformer winding having a second number of windings, and the load is connected to a third transformer winding magnetically connected to the first transformer winding and the second transformer winding.

25. The switchless high efficiency amplifier of claim 24, wherein the first voltage amplifier and the second voltage amplifier have identical operating voltages.

26. The switchless high efficiency amplifier of claim 24, wherein the first gain is greater than the second gain.

27. The switchless high efficiency amplifier of claim 24, wherein the first number of windings is greater than the second number of windings.

28. The switchless high efficiency amplifier of claim 24, wherein a ratio of the first gain to the second gain is equal to a ratio of the first number of windings to the second number of windings.

19. A switchless high efficiency amplifier comprising:

a first parallel path including a first voltage amplifier defined by a first gain;

a second parallel path including a second voltage amplifier defined by a second gain, and a first resistor in series with the second voltage amplifier;

a first voltage supply providing a first supply voltage to the first parallel path and the second parallel path, wherein the first parallel path will have a first output voltage and the second parallel path will have a second output voltage;

a load having a first end connected to the first output voltage and the second output voltage, and a second end connected to a reference voltage, wherein current will flow through the load from the greater of the first output voltage and the second output voltage to the reference voltage, further wherein the first parallel path logically disconnects from the load when the first supply voltage exceeds a certain value.

29. A method for operating amplifiers that can handle peak inputs at a high efficiency, the method comprising:

supplying a first input to a first amplifier and a second amplifier;

producing a first output from the first amplifier;

producing a second output from the second amplifier and reducing the second output by passing it through a first resistive element to produce a third output;

providing the greater of the first output and the third output to a load; and

flowing current to the load, wherein the current is generated from the greater of the first output and the third output.

30. The method of claim 29, wherein the first amplifier and the second amplifier have identical gains so that the first output and the second output are identical.

31. The method of claim 29, wherein the input, the first output, the second output and the third output are voltages.

32. The method of claim 31, wherein the first resistive element is a resistor and the second output voltage drops across the resistor.

35. The method of claim 29, wherein the first input is a positive voltage, the first amplifier is a positive low voltage amplifier and the second amplifier is a positive high voltage amplifier, the method further comprising

supplying a negative voltage to a negative low voltage amplifier and a negative high voltage amplifier;

producing a fourth output voltage from the negative low voltage amplifier;

producing a fifth output voltage from the negative high voltage amplifier and providing the fifth output voltage to a second resistor, wherein the fifth output voltage drops across the second resistor to produce a sixth output voltage; and

flowing current through the load from the greater of the first output voltage and the third output voltage to the greater of the absolute value of the fourth output voltage and the sixth output voltage.

36. The method of claim 35, wherein the positive low voltage amplifier, the positive high voltage amplifier, the negative low voltage amplifier and the negative high voltage amplifier all have an identical gain.

37. The method of claim 35, further comprising logically disconnecting the positive low voltage amplifier from the load when the positive voltage exceeds a first value and logically disconnecting the negative low voltage amplifier from the load when the negative voltage exceeds a second value.

38. The method of claim 29, wherein the gain of the first amplifier is greater that the gain of the second amplifier.

39. The method of claim 38, wherein the providing the greater of first output and the third output includes

providing the first output to a first winding of a transformer;

providing the third output to a second winding of the transformer, wherein current will flow through the first winding if the first output is greater than the third output, and current will flow through the second winding if the third output is greater than the first output; and

providing a voltage across a third winding of the transformer, wherein the voltage corresponds to the greater of the first output and the third output.

40. The method of claim 39, wherein the transformer has a first winding to second winding ratio that is equal to a ratio of a gain of the first amplifier to a gain of the second amplifier.

33. A method for operating amplifiers that can handle peak inputs at a high efficiency, the method comprising:

supplying a first input to a first amplifier and a second amplifier, wherein the first amplifier is a low voltage amplifier and the second amplifier is a high voltage amplifier;

producing a first output from the first amplifier;

producing a second output from the second amplifier and reducing the second output by passing it through a first resistive element to produce a third output; and

providing the greater of the first output and the third output to a load.

34. The method of claim 33, further comprising logically disconnecting the low voltage amplifier from the load when the first input exceeds a certain value.

41. A switchless high efficiency amplifier comprising;

an input supply;

a node;

a first parallel path from the input supply to the node which includes a first amplifier defined by a first gain and a first winding of a transformer in series with the first amplifier;

a second parallel path from the input supply to the node which includes a second amplifier defined by a second gain, a resistor, and a second winding of the transformer, the second amplifier, the resistor and the second winding being in series with each other;

a third winding of the transformer magnetically connected to the first winding and the second winding; and

a load coupled to the third winding.

42. The switchless high efficiency amplifier of claim 41, wherein the node is ground.

43. The switchless high efficiency amplifier of claim 41, wherein the ratio of the first winding to the second winding is the same as the ratio of the first gain to the second gain.

44. The switchless high efficiency amplifier of claim 41, wherein the operating range of the first amplifier and the second amplifier is the same.