Method and apparatus for controlling gain of an amplifier by comparing a detected output envelope and a reference signal

• US 5,841,319 A
• Filed: 01/21/1997
• Issued: 11/24/1998
• Est. Priority Date: 01/24/1996
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Sato, Hideaki
• Primary Examiner(s): MOTTOLA, STEVEN J
• Application Number:
  US08/785,791
• Time in Patent Office: 672 Days
• Field of Search: 330/129, 330/140, 330/141, 330/279, 330/281
• US Class Current: 330/129
• CPC Class Codes: H03G 3/3047 for intermittent signals, e.g. burst signals

Abstract

An envelope level of an output of a variable gain power amplifier is detected by a detector. An envelope level of an output of the variable gain power amplifier detected by the detector and a waveform of a reference signal which is generated from a reference signal generator are compared. A gain of the variable gain power amplifier is controlled in accordance with a comparison output. Upon leading of a transmission output, the reference signal is raised from a grounding level to a rest value of the detector or more and is maintained at a value higher than the rest value of the detector. After the reference signal enters a response range of a negative feedback loop, it is smoothly raised along a cosine square wave. Upon trailing of the transmission output, the reference signal is smoothly reduced to a value near the rest value of the detector along a cosine square wave and is maintained at a value near the rest value of the detector. After the negative feedback loop does not respond, the reference signal is reduced to the rest value of the detector or less.

Claims

1. A power amplifying circuit comprising:

a variable gain power amplifier receiving a transmission signal and producing a transmission output;

a detector for detecting an envelope level of an output of said variable gain power amplifier;

a reference signal generator for generating a reference signal to convert the envelope level of the output of said variable gain power amplifier to a smooth waveform; and

a negative feedback loop including means for comparing the envelope level of the output of said variable gain power amplifier detected by said detector with a waveform of the reference signal from said reference signal generator, thereby producing a control signal for controlling a gain of said variable gain power amplifier in accordance with a comparison output,

wherein a level of the reference signal from said reference signal generator is raised from a value lower than a rest value of said detector to a value higher than said rest value of said detector at a leading edge of the transmission output and is maintained at the value higher than the rest value of said detector and subsequently said level of the reference signal is smoothly raised.

2. The circuit according to claim 1, wherein a waveform of said reference signal which is smoothly raised is a cosine square waveform.

3. A power amplifying circuit comprising:

a variable gain power amplifier receiving a transmission signal and producing a transmission output;

a detector for detecting an envelope level of an output of said variable gain power amplifier;

a reference signal generator for generating a reference signal to convert the envelope level of the output of said variable gain power amplifier to a smooth waveform; and

a negative feedback loop including means for comparing the envelope level of the output of said variable gain power amplifier detected by said detector with a waveform of the reference signal from said reference signal generator, thereby producing a control signal for controlling a gain of said variable gain power amplifier in accordance with a comparison output,

wherein a level of the reference signal from said reference signal generator is smoothly reduced to a value near a rest value of said detector at a trailing edge of the transmission output and is maintained at the value near the rest value of said detector and subsequently said level of the reference signal is reduced to the rest value of said detector or less.

4. The circuit according to claim 3, wherein a waveform of said reference signal which is smoothly reduced is a cosine square waveform.

5. A power amplifying method comprising the step of:

detecting an envelope level of an output of a variable gain power amplifier using a detector;

generating a reference signal to convert the envelope level of the output of said variable gain power amplifier to a smooth waveform using a reference signal generator;

comparing the envelope level of the output of said variable gain power amplifier detected by said detector with a waveform of the reference signal from said reference signal generator, thereby controlling a gain of said variable gain power amplifier in accordance with a comparison output; and

raising a level of the reference signal from said reference signal generator from a value lower than a rest value of said detector to a value higher than the rest value of said detector at a leading edge of a transmission output from said variable gain power amplifier, maintaining said level at the value higher than the rest value of said detector and subsequently smoothly raising said level of the reference signal.

6. The method according claim 5, wherein a waveform of said reference signal which is smoothly raised is a cosine square waveform.

7. A power amplifying method comprising the steps of:

detecting and envelope level of a output of a variable gain power amplifier using a detector;

generating a reference signal to convert the envelope level of the output of said variable gain power amplifier to a smooth waveform using a reference signal generator;

comparing the envelope level of the output of said variable gain power amplifier detected by said detector with a waveform of the reference signal from said reference signal generator, thereby controlling a gain of said variable gain power amplifier in accordance with a comparison output; and

smoothly reducing a level of the reference signal from said reference signal generator to a value near a rest value of said detector at a trailing edge of a transmission output from said variable gain power amplifier, maintaining said level at the value near the rest value of said detector and subsequently reducing said level of the reference signal to rest value of said detector or less.

8. The method according to claim 7, wherein a waveform of said reference signal which is smoothly reduced is a cosine square waveform.

9. A power amplifying circuit comprising:

a variable gain power amplifier receiving a transmission signal and producing a transmission output;

a detector for detecting an envelope level of an output of said variable gain power amplifier;

a reference signal generator including an address generator receiving a transmission control signal for addressing a read only memory and a digital to analog convertor for converting an output of said read only memory for generating a reference signal to convert the envelope level of the output of said variable gain power amplifier to a smooth waveform; and

a negative feedback loop including means for comparing the envelope level of the output of said variable gain power amplifier detected by said detector with a waveform of the reference signal from said reference signal generator, thereby producing a control signal for controlling a gain of said variable gain power amplifier in accordance with a comparison output,

wherein a level of the reference signal from said reference signal generator is raised from a value lower than a rest value of said detector to a value higher than said rest value of said detector at a leading edge of the transmission output and is maintained at the value higher than the rest value of said detector, for a period of time during which said negative feedback loop operates and subsequently said level of the reference signal is smoothly raised.

10. The circuit according to claim 9, wherein a waveform of said reference signal which is smoothly raised is a cosine square waveform.

11. A power amplifying circuit comprising:

a variable gain power amplifier receiving a transmission signal and producing a transmission output;

a detector for detecting an envelope level of an output of said variable gain power amplifier;

a reference signal generator for generating a reference signal to convert the envelope level of the output of said variable gain power amplifier to a smooth waveform; and

a negative feedback loop including means for comparing the envelope level of the output of said variable gain power amplifier detected by said detector with a waveform of the reference signal from said reference signal generator, thereby producing a control signal for controlling a gain of said variable gain power amplifier in accordance with a comparison output,

wherein a level of the reference signal from said reference signal generator is smoothly reduced to a value near a rest value of said detector at a trailing edge of the transmission output and is maintained at the value near the rest value of said detector for a period of time during which said negative feedback loop operates and subsequently said level of the reference signal is reduced to the rest value of said detector or less.

12. The circuit according to claim 11, wherein a waveform of said reference signal which is smoothly reduced is a cosine square waveform.

13. A power amplifying method comprising the steps of:

detecting an envelope level of an output of a variable gain power amplifier using a detector;

generating a reference signal to convert the envelope level of the output of said variable gain power amplifier to a smooth waveform using a reference signal generator;

comparing the envelope level of the output of said variable gain power amplifier detected by said detector with a waveform of the reference signal from said reference signal generator, thereby controlling a gain of said variable gain power amplifier in accordance with a comparison output; and

raising a level of the reference signal from said reference signal generator from a value lower than a rest value of said detector to a value higher than the rest value of said detector at a leading edge of a transmission output from said variable gain power amplifier, maintaining said level at the value higher than the rest value of said detector for a period of time during which a negative feedback loop operates and subsequently raising said level of the reference signal smoothly.

14. The method according to claim 13, wherein a waveform of said reference signal which is smoothly raised is a cosine square waveform.

15. A power amplifying method comprising the steps of:

detecting an envelope level of an output of a variable gain power amplifier using a detector;

generating a reference signal to convert the envelope level of the output of said variable gain power amplifier to a smooth waveform using a reference signal generator;

comparing the envelope level of the output of said variable gain power amplifier detected by said detector with a waveform of the reference signal from said reference signal generator, thereby controlling a gain of said variable gain power amplifier in accordance with a comparison output; and

smoothly reducing a level of the reference signal from said reference signal generator to a value near a rest value of said detector at a trailing edge of a transmission output from said variable gain power amplifier, maintaining said level at the value near the rest value of said detector for a period of time during which a negative feedback loop operates and subsequently reducing said level of the reference signal to the rest value of said detector or less.

16. The method according to claim 15, wherein a waveform of said reference signal which is smoothly reduced is a cosine square waveform.

17. A power amplifying circuit comprising:

a variable gain power amplifier receiving a transmission signal and producing a transmission output;

a detector for detecting an envelope level of an output of said variable gain power amplifier;

a reference signal generator for generating a reference signal to convert the envelope level of the output of said variable gain power amplifier to a smooth waveform; and

a negative feedback loop including means for comparing the envelope level of the output of said variable gain power amplifier detected by said detector with a waveform of the reference signal from said reference signal generator, thereby producing a control signal for controlling a gain of said variable gain power amplifier in accordance with a comparison output,

wherein a level of the reference signal from said reference signal generator is raised from a value lower than a rest value of said detector to a value higher than said rest value of said detector at a leading edge of the transmission output and is maintained at the value higher than the rest value of said detector and subsequently said level of the reference signal is smoothly raised from the start of the operation of said negative feedback loop.

18. The circuit according to claim 17, wherein a waveform of said reference signal which is smoothly raised is a cosine square waveform.

19. A power amplifying method comprising the steps of:

detecting an envelope level of an output of a variable gain power amplifier using a detector;

generating a reference signal to convert the envelope level of the output of said variable gain power amplifier to a smooth waveform using a reference signal generator;

comparing the envelope level of the output of said variable gain power amplifier detected by said detector with a waveform of the reference signal from said reference signal generator, thereby controlling a gain of said variable gain power amplifier in accordance with a comparison output; and

raising a level of the reference signal from said reference signal generator from a value lower than a rest value of said detector to a value higher than the rest value of said detector at a leading edge of a transmission output from said variable gain power amplifier, maintaining said level at the value higher than the rest value of said detector and subsequently smoothly raising said level of the reference signal from the start of the operation of a negative feedback loop.

20. The method according to claim 19, wherein a waveform of said reference signal which is smoothly raised is a cosine square waveform.