Distortion compensating apparatus

• US 20020153950A1
• Filed: 05/28/2002
• Published: 10/24/2002
• Est. Priority Date: 04/21/2000
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Yamamoto, Katsuya, Kusunoki, Shigeo
• Granted Patent: US 6,677,821 B2
• Time in Patent Office: Days
• US Class Current: 330/149
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• CPC Class Codes: H03F 1/3288 to compensate phase shift as a function of the amplitude
• CPC Class Codes: H03F 2201/3233 Adaptive predistortion using lookup table, e.g. memory, RAM, ROM, LUT, to generate the predistortion

Abstract

The present invention relates to a distortion compensating circuit which compensates for non-linear distortion of an output signal of a power amplifying circuit to be used for a transmitting section of a base station or a terminal station of a radio communication system and a radio communication apparatus such as a mobile phone, and more particularly, to improvement of predistorter system widely applicable to a variety of radio communication systems, which does not depend on a use system other than generation of envelope change due to a high frequency input signal without addition of the distortion compensating circuit to a base band portion, and to the distortion compensating circuit in which a memory means 3 where inverted distortion data of a high frequency power amplifying means 12 for a mobile phone or the like is stored in advance is driven with digitalized data obtained by detecting an envelope of a high frequency input signal having envelope change as an address and distortion compensation of the high frequency power amplifying means is made by adjusting the gain of gain variable means 10 provided at a prestage of the high frequency power amplifying means.

Claims

1. A distortion compensating device for carrying out predistortion on a power amplifying means whose distortion should be compensated, comprising:

an envelope detecting means to which a high-frequency signal generating an envelope change is supplied for detecting an envelope signal of said high-frequency signal;

an amplitude correction memory means for storing an inverted distortion amplitude value of a distortion generated in said power amplifying means with digital data obtained by digitalizing the envelope signal of said envelope detecting means as an address; and

a gain variable means disposed in a prestage of said power amplifying means to which the high-frequency signal generating the envelope change is supplied, capable of controlling a passage gain of the high-frequency signal, wherein

the inverted distortion data of said amplitude correction memory means is converted to analog data and supplied to said gain variable means so as to compensate a distortion of the amplitude of a gain of said power amplifying means.

3. The distortion compensating device according to claim 1, further including:

a phase correction memory means, parallel located with said amplitude correction memory means, which stores an inverted distortion phase value of distortion to be generated in said power amplifying means, with digital data obtained by digitalizing the envelope signal of said envelope detecting means as an address; and

a phase-shifting means which can control passage phase of the high frequency signal by supplying analog data that the inverted distortion data of said phase correction memory means is converted into analog data, wherein

the phase-shifting means is connected with said gain variable means in series at the prestage of said power amplifying means.

4. The distortion compensating device according to claim 1 or 3, wherein a delay means for adjusting a difference of delay time between a main path having said power amplifying means and said gain variable means and a corrective control signal route having said envelope detecting means for supplying a control signal to said gain variable means and said amplitude correction memory means is provided in the main path.

6. The distortion compensating device according to claim 4 or 5, wherein by detecting an envelope signal from an output stage of said power amplifying means and feeding back a differential signal obtained by comparing the detected signal with an envelope signal output from said envelope detecting means to said delay means, the delay time is controlled.

7. The distortion compensating device according to claim 1, wherein an output obtained by comparing an output which envelope-detects an output of said power amplifying means with an envelope signal of said envelope detecting means is digitalized and a correction data memory means for storing correction data for correcting a characteristic change by temperature with said digital data as an address is driven so as to multiply the output of said correction data memory means by the output of said amplitude correction memory means thereby compensating a change of the temperature characteristic of said power amplifying means.

2. A distortion compensating device for carrying out predistortion on a power amplifying means whose distortion should be compensated, comprising:

an envelope detecting means to which a high-frequency signal generating an envelope change is supplied for detecting an envelope signal of the high-frequency signal;

a phase correction memory means for storing an inverted distortion phase value of a distortion generated in said power amplifying means with digital data obtained by digitalizing the envelope signal of said envelope detecting means as an address; and

a phase-shifting means disposed in a prestage of said power amplifying means to which the high-frequency signal generating the envelope change is supplied, capable of controlling a passage phase of the high-frequency signal, wherein

the inverted distortion data of said phase correction memory means is converted to analog data and supplied to said phase-shifting means so as to compensate a distortion of the phase of said power amplifying means.

5. The distortion compensating device according to claim 2 or 3, wherein a delay means for adjusting a difference of delay time between a main path having said power amplifying means and said phase-shifting means and a corrective control signal route having said envelope detecting means for supplying a control signal to said phase-shifting means and said phase correction memory means is provided in the main path.

8. A distortion compensating device for carrying out predistortion on a power amplifying means whose distortion should be compensated, comprising:

an envelope detecting means to which a high frequency signal generating an envelope change is supplied for detecting an envelope signal of the high frequency signal;

a phase correction memory means which stores an inverted distortion phase value of distortion to be generated in said power amplifying means with digital data obtained by digitalizing the envelope signal of said envelope detecting means as an address; and

a phase-shifting means which is located at a poststage of said power amplifying means to which the high frequency signal generating the envelope change is supplied and can control passage phase of the high frequency signal, wherein

an inverted distortion data of said phase correction memory means is converted into analog data to supply to said phase-shifting means and distortion of phase of said power amplifying means is compensated.

9. The distortion compensating device according to claim 8, further including:

an amplitude correction memory means, parallel located with said phase correction memory means, which stores an inverted distortion amplitude value of distortion to be generated in said power amplifying means with digital data obtained by digitalizing the envelope signal of said envelope detecting means as an address; and

a gain variable means which can control passage gain of the high frequency signal by supplying analog data that the inverted distortion data of said amplitude correction memory means is converted into analog data, wherein

said gain variable means is connected with the prestage of said power amplifying means.

10. The distortion compensating device according to claim 8 or 9, wherein a delay means for adjusting a difference of delay time between a main path having said power amplifying means and said phase-shifting means and a corrective control signal route having said envelope detecting means for supplying a control signal to said phase-shifting means and said phase correction memory means is provided in the main path.

11. The distortion compensating device according to claim 10, wherein an envelope signal is detected from an output stage of said power amplifying means and a difference signal in which the detected signal is compared with an envelope signal output from said envelope detecting means is fed back to said delay means to control delay time.

12. A distortion compensating device comprising:

a first envelope detecting means for detecting an envelope signal with a part of a high frequency signal having fluctuation of envelope as an input;

a digital-to-analog converting means for converting the envelope signal of said first envelope detecting means into digital data;

an amplitude correction memory means in which digital data is inputted as an address and which outputs amplitude correction data corresponding to the address by means of data stored for amplitude correction in advance;

a first low pass filtering means for converting the amplitude correction data into an analog signal to eliminate digital noise of the analog signal;

a phase correction memory means in which digital data is inputted as an address and which outputs phase correction data corresponding to the address by means of data stored for phase correction in advance;

a second low pass filtering means for converting the phase correction data into an analog signal to eliminate digital noise of the analog signal;

a delay means which can adjust the volume of delay of passing time by means of a control signal to be added into a control terminal with the high frequency signal as an input;

a gain variable means for varying a passage gain depending on the voltage of the signal from said first low pass filtering means, to be added into a control terminal with a delay signal of said delay means as an input;

a phase-shifting means for varying a passage phase by an output signal from said second low pass filtering means with an output of said gain variable means as an input to input a variable output signal into a power amplifying means whose distortion should be compensated;

a second envelope detecting means for detecting an envelope signal of the output of said power amplifying means whose distortion should be compensated;

a subtracting means for detecting a difference between envelope signals with envelope signals of said first and second envelope detecting means as inputs; and

a third low pass filtering means for detecting only a DC signal of said subtracting means, wherein

the DC signal of said third low pass filtering means is fed back to the control terminal of said delay means.

13. A distortion compensating device comprising:

a first envelope detecting means for detecting an envelope signal with a part of a high frequency signal having fluctuation of envelope as an input;

a digital-to-analog converting means for converting the envelope signal of said first envelope detecting means into digital data;

an amplitude correction memory means in which digital data is inputted as an address and which outputs amplitude correction data corresponding to the address by means of data stored for amplitude correction in advance;

a first low pass filtering means for converting the amplitude correction data into an analog signal to eliminate digital noise of the analog signal;

a phase correction memory means in which the digital data is inputted as an address and which outputs phase correction data corresponding to the address by means of data stored for phase correction in advance;

a second low pass filtering means for converting the phase correction data into an analog signal to eliminate digital noise of the analog signal;

a delay means which can adjust the volume of delay of passing time by means of a control signal to be added into a control terminal with the high frequency signal as an input;

a gain variable means for varying a passage gain depending on the voltage of the signal, from said first low pass filtering means, to be added into a control terminal with a delay signal of said delay means as an input;

a phase-shifting means for varying a passage phase by means of an output signal from said second low pass filtering means by inputting an output of said gain variable means into a power amplifying means whose distortion should be compensated and inputting an output of said power amplifying means thereinto;

a second envelope detecting means for detecting an envelope signal of the output of said phase-shifting means;

a subtracting means for detecting a difference between envelope signals with envelope signals of said first and second envelope detecting means as inputs; and

a third low pass filtering means for detecting only a DC signal of said subtracting means, wherein

the DC signal of said third low pass filtering means is fed back to the control terminal of said delay means.

14. A distortion compensating device comprising:

a first envelope detecting means for detecting an envelope signal with a part of a high frequency signal having fluctuation of envelope as an input;

a digital-to-analog converting means for converting the envelope signal of said first envelope detecting means into digital data;

an amplitude correction memory means in which the digital data is inputted as an address and which outputs amplitude correction data corresponding to the address by means of data stored for amplitude correction in advance;

a multiplying means in which digital multiplier is the product with a digital output of said amplitude correction memory means as multiplicand;

a first low pass filtering means for converting digital data of said multiplying means to an analog signal to eliminate digital noise of the analog signal;

a phase correction memory means in which the digital data is inputted as an address and which outputs phase correction data corresponding to the address by means of data stored for phase correction in advance;

a second low pass filtering means for converting the phase correction data into an analog signal to eliminate digital noise of the analog signal;

a delay means which can adjust the volume of delay of passing time by means of a control signal to be added into a control terminal with the high frequency signal as an input;

a gain variable means for varying a passage gain depending on the voltage of the signal from said first low pass filtering means, to be added into a control terminal with a delay signal of said delay means as an input;

a phase-shifting means for varying a passage phase by an output signal from said second low pass filtering means with an output of said gain variable means as an input to input a variable output signal into a power amplifying means whose distortion should be corrected;

a second envelope detecting means for detecting an envelope signal of the output of said power amplifying means whose distortion should be corrected;

a subtracting means for detecting a difference between envelope signals with envelope signals of said first and second envelope detecting means as inputs;

a third low pass filtering means for detecting only a DC signal of said subtracting means to feed it back to the control terminal of said delay means; and

a correction data memory means for outputting data, corresponded to the address, which corrects a change of characteristic due to temperature with output of digital data in which an output difference signal of said subtracting means is digitalized as an address, wherein

data corresponding to the address from said correction data memory means is supplied as multiplier of said multiplying means.