Nonlinear compensator

• US 6,771,708 B1
• Filed: 09/18/2000
• Issued: 08/03/2004
• Est. Priority Date: 09/30/1999
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Sawada, Takeshi, Suga, Masaru, Isobe, Seiji
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Ha, Dac V.
• Application Number:
  US09/664,345
• Time in Patent Office: 1,415 Days
• Field of Search: 375/284, 375/285, 375/295-297, 375/146, 375/278, 455/43, 455/50.1, 455/63, 455/295, 332/107, 332/123, 332/124, 332/159, 332/160, 332/176, 332/177
• US Class Current: 375/278
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• CPC Class Codes: H03F 1/3282 Acting on the phase and the amplitude of the input signal
• CPC Class Codes: H03F 2200/336 A I/Q, i.e. phase quadrature, modulator or demodulator being used in an amplifying circuit

Abstract

A nonlinear compensator comprising a signal processing section, a distortion detecting section, and a distortion correcting section. The signal processing section detects the time difference and phase difference between two signals by calculating correlation, synchronizes the two signals with each other, and causes the phase of one signal to coincide with that of the other. The distortion detecting section determines an amplitude error and a phase error in the two signals and inputs the errors as distortion components to a distortion correcting section. The distortion correcting section sequentially selects the amplitude, the phase, and the amount of compensation corresponding to the value of the amplitude from the amounts of compensation registered at the initial stage and updated adaptively, and adds the amount of compensation to the digital base band signal obtained at the input demodulation section to compensate for the distortion components.

Claims

1. A nonlinear compensator for compensating for the nonlinear characteristic of a compensated electronic device that deals with a transfer signal, said nonlinear compensator comprising:

a signal processing section which takes in an input signal and an output signal of said compensated electronic device, demodulates the signals suitably in such a manner that they have the same signal form, detects the time difference and phase difference between the two signals by correlating the two signals with each other, and not only synchronizes the two signals with each other but also causes the phase of one signal to coincide with that of the other on the basis of the detected time difference and phase difference;

a distortion detecting section for detecting, as distortion components, an amplitude error and phase error in the input signal and output signal of said compensated electronic device that have been synchronized with each other and made in phase with one another by the signal processing section; and

a distortion correcting section for producing the amount of nonlinear distortion compensation for said compensated electronic device on the basis of the distortion components detected by the distortion detecting section and compensating for the input signal to said compensated electronic device on the basis of the amount of distortion compensation;

wherein said signal processing section includes an input demodulation section for generating an input-side base band signal by demodulating the transfer signal to said compensated electronic device and an output demodulation section for generating an output-side base band signal by demodulating the transfer signal outputted from said compensated electronic device, detects the time difference and phase difference between the input-side and output-side base band signals obtained at said input demodulation section and output demodulation section, and not only synchronizes the two signals with each other but also causes the phase of one signal to coincide with that of the other on the basis of the detected time difference and phase difference, and further includes an output converting section for converting the output of said distortion correcting section into the format of the original transfer signal.

2. A nonlinear compensator for compensating for the nonlinear characteristic of a compensated electronic device that deals with a transfer signal, said nonlinear compensator comprising:

a signal processing section which takes in an input signal and an output signal of said compensated electronic device, demodulates the signals suitably in such a manner that they have the same signal form, detects the time difference and phase difference between the two signals by correlating the two signals with each other, and not only synchronizes the two signals with each other but also causes the phase of one signal to coincide with that of the other on the basis of the detected time difference and phase difference;

a distortion detecting section for detecting, as distortion components, an amplitude error and phase error in the input signal and output signal of said compensated electronic device that have been synchronized with each other and made in phase with one another by the signal processing section; and

a distortion correcting section for producing the amount of nonlinear distortion compensation for said compensated electronic device on the basis of the distortion components detected by the distortion detecting section and compensating for the input signal to said compensated electronic device on the basis of the amount of distortion compensation;

wherein said signal processing section delays the input signal to said compensated electronic device according to the amount of delay equivalent to the detected time difference.

3. A nonlinear compensator for compensating for the nonlinear characteristic of a compensated electronic device that deals with a transfer signal, said nonlinear compensator comprising:

a signal processing section which takes in an input signal and an output signal of said compensated electronic device, demodulates the signals suitably in such a manner that they have the same signal form, detects the time difference and phase difference between the two signals by correlating the two signals with each other, and not only synchronizes the two signals with each other but also causes the phase of one signal to coincide with that of the other on the basis of the detected time difference and phase difference;

a distortion detecting section for detecting, as distortion components, an amplitude error and phase error in the input signal and output signal of said compensated electronic device that have been synchronized with each other and made in phase with one another by the signal processing section; and

a distortion correcting section for producing the amount of nonlinear distortion compensation for said compensated electronic device on the basis of the distortion components detected by the distortion detecting section and compensating for the input signal to said compensated electronic device on the basis of the amount of distortion compensation;

wherein said signal processing section gives the amount of phase shift equivalent to the detected phase difference to the input signal or output signal of said compensated electronic device.

4. A nonlinear compensator for compensating for the nonlinear characteristic of a compensated electronic device that deals with a transfer signal, said nonlinear compensator comprising:

a signal processing section which takes in an input signal and an output signal of said compensated electronic device, demodulates the signals suitably in such a manner that they have the same signal form, detects the time difference and phase difference between the two signals by correlating the two signals with each other, and not only synchronizes the two signals with each other but also causes the phase of one signal to coincide with that of the other on the basis of the detected time difference and phase difference;

a distortion detecting section for detecting, as distortion components, an amplitude error and phase error in the input signal and output signal of said compensated electronic device that have been synchronized with each other and made in phase with one another by the signal processing section; and

a distortion correcting section for producing the amount of nonlinear distortion compensation for said compensated electronic device on the basis of the distortion components detected by the distortion detecting section and compensating for the input signal to said compensated electronic device on the basis of the amount of distortion compensation;

wherein said distortion correcting section includes an amount-of-compensation table for holding said amount of distortion compensation, registers said amount of distortion compensation at the time of initial setting, reads the amount of distortion compensation corresponding to the amplitude of the input signal to said compensated electronic device from the amount-of-compensation table during service, and compensates for the input signal.

5. The nonlinear compensator according to claim 4, wherein the amount-of-compensation table in said distortion correcting section includes a present-use table and a standby table, stores the amount of distortion compensation obtained at said distortion detecting section and, after the storage has been completed, replaces the present-use table with the standby table.

6. A nonlinear compensator for compensating for the nonlinear characteristic of a compensated electronic device that deals with a transfer signal, said nonlinear compensator comprising:

a signal processing section which takes in an input signal and an output signal of said compensated electronic device, demodulates the signals suitably in such a manner that they have the same signal form, detects the time difference and phase difference between the two signals by correlating the two signals with each other, and not only synchronizes the two signals with each other but also causes the phase of one signal to coincide with that of the other on the basis of the detected time difference and phase difference;

a distortion detecting section for detecting, as distortion components, an amplitude error and phase error in the input signal and output signal of said compensated electronic device that have been synchronized with each other and made in phase with one another by the signal processing section;

a distortion correcting section for producing the amount of nonlinear distortion compensation for said compensated electronic device on the basis of the distortion components detected by the distortion detecting section and compensating for the input signal to said compensated electronic device on the basis of the amount of distortion compensation; and

monitor means for monitoring said compensated electronic device by monitoring the distortion components obtained at said distortion detecting section.

7. A nonlinear compensator for compensating for the nonlinear characteristic of a compensated electronic device that deals with a transfer signal, said nonlinear compensator comprising:

a signal processing section which takes in an input signal and an output signal of said compensated electronic device, demodulates the signals suitably in such a manner that they have the same signal form, detects the time difference and phase difference between the two signals by correlating the two signals with each other, and not only synchronizes the two signals with each other but also causes the phase of one signal to coincide with that of the other on the basis of the detected time difference and phase difference;

a distortion detecting section for detecting, as distortion components, an amplitude error and phase error in the input signal and output signal of said compensated electronic device that have been synchronized with each other and made in phase with one another by the signal processing section; and

a distortion correcting section for producing the amount of nonlinear distortion compensation for said compensated electronic device on the basis of the distortion components detected by the distortion detecting section and compensating for the input signal to said compensated electronic device on the basis of the amount of distortion compensation;

wherein said signal processing section includes carrier synchronizing means for synchronizing the carrier frequency and carrier phase of the input signal to said compensated electronic device with those of the output signal of said compensated electronic device on the basis of the detected phase difference.