Feed-forward amplifier device and method thereof

Patent metadata

Field	Value
Publication number	US-9369092-B2
Application number	US-201214380465-A
Country	US
Kind code	B2
Filing date	Feb 24, 2012
Priority date	Feb 24, 2012
Publication date	Jun 14, 2016
Grant date	Jun 14, 2016

Abstract

The present application discloses a feed-forward amplifier device and the method thereof. The device comprises: a splitter for splitting an input signal into two portions; a non-linear amplifier for amplifying the input signal and producing inter-modulation products; a carrier canceling unit for generating pure inter-modulation products; a linear amplifier for amplifying the pure inter-modulation products; and a coupler for generating final output signal by counteracting the inter-modulation products with the amplified pure inter-modulation products; wherein the splitter and the carrier canceling unit are provided in digital base band. According to the present disclosure, pure inter-modulation products can be generated and adjusted more flexibly and more accurately in digital base band, and hence ideal output signal may be generated.

First claim

What is claimed is:

1. A feed-forward amplifier device comprising:
a splitter for splitting an input signal into a first portion and a second portion;
a first set of digital-analog converters (DACs) for converting the first portion of the input signal from a digital format to an analog format;
a first set of in-phase/quadrate-phase (IQ) modulators for orthogonally modulating the first portion of the input signal to a radio frequency (RF) carrier;
a non-linear amplifier for amplifying the first portion of the input signal and producing inter-modulation products;
a carrier canceling unit for generating pure inter-modulation products based on the second portion of the input signal and the non-linear amplifier's output signal;
a second set of DACs for converting the pure inter-modulation products from a digital format to an analog format;
a second set of IQ modulators for orthogonally modulating the pure inter-modulation products to another RF carrier;
a linear amplifier for amplifying the pure inter-modulation products; and
a coupler after the non-linear amplifier for generating a final output signal by counteracting the inter-modulation products with the amplified pure inter-modulation products;
wherein the splitter and the carrier canceling unit are provided in digital base band, and the splitter, carrier canceling unit, linear amplifier, and coupler constitute a feed-forward loop for feeding forward the pure inter-modulation products into the coupler,
digital-analog converters (DACs) for converting signals from digital signals into analog signals; and
in-phase/quadrate-phase (IQ) modulators for orthogonally modulating analog signals to a radio frequency (RF) carrier.

2. The device according to claim 1 , further comprising:
a second coupler after the non-linear amplifier, for coupling part of the non-linear amplifier's output signal;
an observation receiver for feeding back the coupled output signal from the non-linear amplifier into the carrier canceling unit;
wherein the splitter, non-linear amplifier, second coupler, observation receiver, and carrier canceling unit constitute a first feedback loop for feeding back the non-linear amplifier's output signal into the carrier canceling unit.

3. The device according to claim 2 , further comprising:
a vector adjustor after the carrier canceling unit in digital base band, for adjusting at least one of an amplitude, phase, and delay of the pure inter-modulation products;
wherein the vector adjustor is included in the feed-forward loop.

4. The device according to claim 3 , further comprising:
a third coupler after the coupler, for coupling part of the final output signal and feeding back it to the observation receiver;
a vector adjust parameter calculating unit for generating adjust parameters for the vector adjustor by comparing a final output signal from the observation receiver with an input signal from the splitter;
wherein the splitter, the non-linear amplifier, the second coupler, the coupler, the third coupler, the observation receiver, and the vector adjust parameter calculating unit constitute a second feedback loop, and the vector adjustor adjusts at least one of an amplitude, phase, and delay of the pure inter-modulation products with the adjust parameters.

5. The device according to claim 4 , further comprising a plurality of switches for switching between the first feedback loop and the second feedback loop.

6. The device according to claim 1 , wherein the pure inter-modulation products generated by the carrier canceling unit are phase inversed relative to the non-linear amplifier's output signal.

7. The device according to claim 3 , wherein the vector adjustor further comprises:
an amplitude adjustor for adjusting the amplitude of the pure inter-modulation products;
a phase adjustor for adjusting the phase of the pure inter-modulation products; and/or
a delay adjustor for calibrating the delay of the pure inter-modulation products.

8. The device according to claim 2 , wherein the observation receiver further comprises:
a mixer for down converting a feedback signal into an intermediate frequency (IF) signal with lower frequency;
an IF filter for filtering out high frequency interference and/or local oscillator leakage in the IF signal; and
an analog-digital converter (ADC) for converting the IF signal into a digital signal in base band.

9. The device according to claim 1 , further comprising an amplitude compensator, a phase compensator, and a delay compensator after the splitter, for compensating the amplitude, phase and delay of the input signal, respectively.

10. The device according to claim 1 , further comprising a digital delayer after the splitter for compensating time delay in digital domain.

11. The device according to claim 1 , further comprising an analog delayer connected to an input of the coupler, for compensating a process delay in the first feedback loop and/or a pure inter-modulation products propagation delay in the feed-forward loop.

12. The device according to claim 2 , further comprising a digital down converter after the observation receiver for down converting digitized signals to zero frequency in digital domain.

13. A method for feed-forward amplifying a signal, the method comprising of:
splitting an input signal into a first portion and a second portion in digital base band;
converting the first portion of the input signal from a digital format to an analog format;
orthogonally modulating the first portion of the input signal to a radio frequency (RF) carrier;
non-linearly amplifying the first portion of the input signal in analog domain;
generating pure inter-modulation products in digital base band based at least on the second portion of the input signal;
converting the pure inter-modulation products from a digital format to an analog format;
orthogonally modulating the pure inter-modulation products to another RF carrier;
linearly amplifying the pure inter-modulation products in analog domain; and
generating a final output signal without inter-modulation products.

14. A method for feed-forward amplifying a signal, the method comprising of:
splitting an input signal into a first portion and a second portion in digital base band;
converting the first portion of the input signal from a digital format to an analog format;
orthogonally modulating the first portion of the input signal to a radio frequency (RF) carrier;
non-linearly amplifying the input signal in analog domain;
feeding back the amplified input signal into digital base band;
generating pure inter-modulation products in digital base band based at least on the second portion of the input signal;
converting the pure inter-modulation products from a digital format to an analog format;
orthogonally modulating the pure inter-modulation products to another RF carrier;
linearly amplifying the pure inter-modulation products in analog domain; and
generating a final output signal without inter-modulation products.

15. The method according to claim 14 , further comprising adjusting the pure inter-modulation products in digital domain before linearly amplifying, wherein at least one of an amplitude, phase and delay of the pure inter-modulation products are adjusted in digital domain.

16. The method according to claim 15 , further comprising:
feeding back the final output signal into digital base band;
generating adjust parameters by comparing the input signal with the final output signal;
wherein adjusting the pure inter-modulation products comprises adjusting the pure inter-modulation products wi

Assignees

• Zeng Xiang
• Yang Changjiang
• Huang Tao
• Ericsson Telefon Ab L M

Inventors

• Zeng Xiang
• Yang Changjiang
• Huang Tao

Classifications

• H03F3/19

  with semiconductor devices only · CPC title

• H03F2200/451

  the amplifier being a radio frequency amplifier · CPC title

• H03F3/211

  using a combination of several amplifiers (H03F3/60 takes precedence) · CPC title

• H03F1/3223 Primary

  using feed-forward (H03F1/3211 takes precedence) · CPC title

• H03F1/3229

  using a loop for error extraction and another loop for error subtraction · CPC title