Method and apparatus for high efficiency wideband power amplification

• US 6,175,273 B1
• Filed: 04/02/2000
• Issued: 01/16/2001
• Est. Priority Date: 10/06/1997
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Raab, Frederick H., Clark, James Roger II, Sigmon, Bernard Eugene
• Primary Examiner(s): Shingleton, Michael B
• Application Number:
  US09/541,327
• Time in Patent Office: 289 Days
• Field of Search: 330/10, 330/126, 330/136, 330/124.R, 332/159, 332/149, 332/107, 332/123
• US Class Current: 330/10
• CPC Class Codes: H03F 1/0222 by using a signal derived from the input signal
• CPC Class Codes: H03F 2200/102 A non-specified detector of a signal envelope being used in an amplifying circuit
• CPC Class Codes: H03F 2200/39 Different band amplifiers are coupled in parallel to broadband the whole amplifying circuit
• CPC Class Codes: H03F 2200/432 Two or more amplifiers of different type are coupled in parallel at the input or output, e.g. a class D and a linear amplifier, a class B and a class A amplifier
• CPC Class Codes: H03F 3/211 using a combination of several amplifiers H03F3/60 takes precedence

Abstract

A method and apparatus for efficient power amplification of a wideband signal with a correspondingly wide modulation bandwidth includes an envelope detector (220), an adaptive split band modulator (270), and a power amplifier (260). The adaptive split band modulator (270) amplifies the low frequency components using a class S modulator (760), and amplifies the high frequency components using a class B amplifier (750). The power supply of the class B amplifier (750) is adaptively modified as a function of the amplitude of the signal that it amplifies. In this manner, the class B amplifier (750) operates at a higher efficiency.

Claims

1. An adaptive split band modulator comprising:

a first amplifier having an input coupled to an input of said adaptive split band modulator;

a peak detector having an input coupled to said input of said adaptive split band modulator;

a second amplifier having an input coupled to said input of said adaptive split band modulator, and having a power supply input coupled to an output of said peak detector; and

a combining network for combining an output of said first amplifier and an output of said second amplifier.

2. The adaptive split band modulator of claim 1 wherein said first amplifier comprises a class S modulator.

3. The adaptive split band modulator of claim 1 wherein said second amplifier comprises a class B amplifier.

4. The adaptive split band modulator of claim 1 further comprising a voltage regulator coupled between said output of said peak detector and said power supply input of said second amplifier.

5. The adaptive split band modulator of claim 1 wherein said combining network comprises a low pass filter coupled to said output of said first amplifier.

6. The adaptive split band modulator of claim 1 wherein said combining network comprises a high pass filter coupled to said output of said second amplifier.

7. An adaptive split band modulator for amplifying an input signal having a low frequency component and a high frequency component, said adaptive split band modulator comprising:

first amplifying means for amplifying said low frequency component of said input signal;

second amplifying means for amplifying said high frequency component of said input signal;

detecting means for detecting an amplitude of said high frequency component of said input signal; and

means, responsive to said amplitude of said high frequency component of said input signal, for adaptively modifying a power supply voltage used to power said second amplifying means.

8. The adaptive split band modulator of claim 7 wherein said first amplifying means comprises a class S modulator.

9. The adaptive split band modulator of claim 7 wherein said second amplifying means comprises a class B amplifier.

10. The adaptive split band modulator of claim 7 wherein said detecting means comprises a peak detector.

11. The adaptive split band modulator of claim 7 wherein said means for adaptively modifying a power supply voltage comprises a voltage regulator.