Amplifying apparatus

• US 7,133,466 B2
• Filed: 11/24/2004
• Issued: 11/07/2006
• Est. Priority Date: 05/31/2002
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Maruyama, Satoshi
• Primary Examiner(s): Fan, Chien M.
• Assistant Examiner(s): Lu, Jia
• Application Number:
  US10/999,207
• Publication Number:
  US 20050141640A1
• Time in Patent Office: 713 Days
• Field of Search: 375/297, 375/295, 375/311
• US Class Current: 375/297
• CPC Class Codes: H03F 1/3241 using predistortion circuits H03F1/3211, H03F1/3217 take precedence
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• CPC Class Codes: H03F 1/52 Circuit arrangements for protecting such amplifiers monitoring arrangements G01R31/28; increasing reliability in communication systems, e.g. using redundancy H04B1/74
• CPC Class Codes: H03F 3/211 using a combination of several amplifiers H03F3/60 takes precedence
• CPC Class Codes: H03G 1/0088 using discontinuously variable devices, e.g. switch-operated
• CPC Class Codes: H03G 2201/103 being an amplifying element
• CPC Class Codes: H03G 2201/206 being in radio frequency
• CPC Class Codes: H03G 2201/307 being radio frequency signal
• CPC Class Codes: H03G 2201/504 by summing selected parallel amplifying paths, i.e. more amplifying/attenuating paths summed together
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04

Abstract

The present invention provides an amplifying apparatus including, two amplifiers for receiving input signals in common and for outputting their respective amplified signals, a combiner for combining the output signals of the two amplifiers and for outputting a combined signal, the amplifying apparatus which inhibit the distortion component in the output of amplifiers in the transition state. This amplifying apparatus comprises, a predistortion unit for determining a distortion compensation component based on the output of the combiner and for predistorting the input based on the determined distortion compensation component, and a gain control unit for attenuating the inputs to set lower than in the steady state by reducing the gain in the transition from two amplifier operation to one amplifier operation, or in the transition from one amplifier operation to two amplifier operation, or at the time of removal or attachment the amplifiers.

Claims

1. An amplifying apparatus comprising:

two transmission amplifiers; and

a combiner for combining output signals of the two transmission amplifiers and for outputting a combined signal,

wherein each transmission amplifier includes;

a predistortion unit for determining a distortion compensation component based on the output signal of the combiner, and for predistorting an input signal of the transmission amplifier based on the determined distortion compensation component; and

a gain control unit for attenuating the predistorted input signal to set lower than in the steady state by reducing the gain lower than a steady value in the transition from the state where both of the transmission amplifiers operate to the state where either of the transmission amplifiers operates, or in the transition from the state where either of the transmission amplifiers operates to the state where both of the amplifiers operate, or at the time of removal of either of the transmission amplifiers, or at the time of attachment of the removed transmission amplifier an amplifier for receiving the attenuated predistorted input signal and for outputting an amplified signal.

2. The amplifying apparatus of claim 1, wherein the gain control unit attenuates the predistorted input signal to set lower than in the steady state if power of the input signal or power of the output signal of the combiner is greater than a given value in the transition from the state where both of the transmission amplifiers operate to the state where either of the transmission amplifiers operates, or in the transition from the state where either of the transmission amplifiers operates to We state where both of the transmission amplifiers operate, or at the time of removal of either of the transmission amplifiers, or at the time of attachment of the removed transmission amplifier.

3. The amplifying apparatus of claim 2, wherein the given value is a power value of the input signal at the boundary between the linear and nonlinear regions of the amplification characteristic of the transmission amplifiers in operation.

4. The amplifying apparatus of claim 1, wherein the gain control unit changes the amount of decline in the gain in response to the power of the predistorted input signal or the power of the output signal of the combiner in the transition from the state where both of the transmission amplifiers operate to the state where either of the transmission amplifiers operates, or in the transition from the state where either of the transmission amplifiers operates to the state where both of the transmission amplifiers operate, or at the time of removal of either of the transmission amplifiers, or at the time of attachment of the removed amplifier.

5. The amplifying apparatus of claim 1, wherein the gain control unit restores the gain to the steady value after a lapse of a given time after reducing the gain lower than the steady value.

6. The amplifying apparatus of claim 5, wherein the gain control unit restores the gain to the steady value in a stepwise manner.

7. The amplifying apparatus of claim 5, wherein the gain control unit restores the gain to the steady value by repeating a plurality of times the steps of first restoring the gain by a given value that is smaller than the difference between the reduced value and the steady value and then restoring the gain again by the given value when the distortion component contained in the output signal of the combiner converges into an allowable range.

8. The amplifying apparatus of claim 5, wherein the given time is a time required for the distortion component contained in the output signal of the combiner to converge into the allowable range.

9. The amplifying apparatus of claim 1, farther comprising two fault detection units each for imparting a fault detection signal to the gain control unit in the event of detection of a fault, wherein the gain control unit reduces the gain lower than the steady value upon receiving the fault detection signal.

10. An amplifying apparatus comprising:

two amplifiers for receiving selected signals in common and for outputting their respective amplified signals;

a combiner for combining the output signals of the two amplifiers and for outputting a combined signal;

two predistortion units each for determining a distortion compensation component based on the output signal of the combiner, and for predistorting input signal based on the determined distortion compensation component;

a switch unit for selecting one of output signals of the two predistortion units and for supplying the selected output signal to the two amplifiers in common; and

a gain control unit for attenuating the signals input to the switch to set lower than in the steady state by reducing the gain lower than a steady value when changing over the switch unit from one of the predistortion units to the other.

11. An amplifying apparatus comprising:

two amplifying units;

a combiner for combining output signals of the two amplifying units and for outputting a combined signal; and

a switch unit,

each of the two amplifying units including;

a main amplifier;

a digital predistoner disposed at the input side of the main amplifier, and for generating a predictive distortion value of the main amplifier and for adding the generated predictive distortion value to input signals;

a quadrature modulator for quadrature-modulating an output signal of the digital predistorter;

an upconverter for converting the frequency of an output signal of the quadrature modulator;

a downconverter for converting the frequency of an output signal of the combiner and for imparting the frequency-converted output signal of the combiner to the digital predistorter, and

a gain control unit for receiving an output signal of the upconverter as input, and for attenuating the input signal to the gain control unit to set lower than in the steady state by reducing the gain lower than a steady value in the transition from the state where both of the amplifying units operate to the state where either of the amplifying units operates, or in the transition from the state where either of the amplifying units operates to the state where both of the amplifying units operate, or at the time of removal of either of the amplifying units, or at the time of attachment of the removed amplifying unit, or at the time of changing over of the switch unit from one predistortion unit to the other predistortion unit,

wherein the switch unit selects an output signal of one of the gain control units of the two transmission amplifying units and imparts the selected output signal to the main amplifiers in common.