Linearization of multi-antenna receivers with RF pre-distortion
AssigneeTelefonaktiebolaget L M Ericsson (publ)
InventorMark Wyville
Life of this patent
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Abstract
A receiver includes a first receiver chain configured to receive a first input signal and a second receiver chain configured to receive a second input signal. A first phase predistorter is provided in the first receiver chain and is configured to shift a phase of the first input signal by a first phase shift φ′A(f). A combiner is coupled to the first receiver chain and the second receiver chain and combines the first and second input signals. The first phase shift is selected to cause undesired signal components received in the first and second input signals to combine destructively.
Claims12
A receiver, comprising:
- a first receiver chain configured to receive a first input signal;
- a second receiver chain configured to receive a second input signal;
- a first phase predistorter in the first receiver chain configured to shift a phase of the first input signal by a first phase shift φ′A(f);
- a second phase predistorter in the second receiver chain configured to shift a phase of the second input signal by a second phase shift φ′B(f);
- and
- a combiner coupled to the first receiver chain and the second receiver chain and configured to combine the first and second input signals;
- wherein the first phase shift is selected to cause undesired signal components induced in the first and second input signals by nonlinear processing in the receiver to combine destructively;
- wherein the first phase shift and the second phase shift are jointly selected to cause the undesired signal components in the first and second input signals to combine destructively;
- and
- wherein the undesired signal components comprise intermodulation distortion (IMD) products of a first undesired signal and a second undesired signal, wherein a phase difference between a first one of the IMD products in the first input signal and a second one of the IMD products in the second input signal has the form:
- Δφ,IM3=2Δ′φ(f2)−Δ′φ(f1)
- wherein Δ′φ(f) is defined as (φA(f)+φ′A(f))−(φB(f)+φ′B(f)), f1 is a fundamental frequency of the first undesired signal, f2 is a fundamental frequency of the second undesired signal, wherein φA(f) and φB(f) are phase shifts of the first and second input signals, and wherein φ′A(f) and φ′B(f) are frequency dependent phase shifts selected such that Δφ,IM3 is about +/−180 degrees.
A method of prosessing a signal that is received on multiple antennas, comprising:
- receiving a first input signal from a first antenna;
- receiving a second input signal from a second antenna;
- shifting a phase of the first input signal by a first phase shift φ′hd A(f);
- shifting a phase of the second input signal by a second phase shift φ′B (f);
- and
- combinina the first and second input signals;
- wherein the first phase shift is selected to cause undesired signal components induced in the first and second input signals by nonlinear processing to combine destructively;
- wherein the first and second phase shifts are selected to cause the undesired signal components in the first and second input signals to combine destructively;
- and
- wherein the undesired signal components comprise intermodulation distortion (IMD) products of a first undesired signal and a second undesired signal, wherein a phase difference between a first one of the IMD products received in the first input signal and a second one of the IMD products received in the second input signal has the form:
- Δφ,IM3=2Δ′φ(f2)−Δ′φ(f1)
- wherein Δ′φ(f) is defined as (φA(f)+φ′A(f))−(φB(f)+φ′B(f)), f1 is a fundamental frequency of the first undesired signal, f2 is a fundamental frequency of the second undesired signal, wherein φA(f) and φB(f) are phase shifts of the first and second input signals, and wherein φ′A(f) and φ′B(f) are frequency dependent phase shifts selected such that Δφ,IM3 is about +/−180 degrees.
Dependencies are inferred from the claim text.