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US 8,712,356 B2Granted
Apparatus and method for phase synchronization in radio frequency transmitters
AssigneeAnalog Devices, Inc.
InventorsAntonio Montalvo, Jianxun Fan
Life of this patent
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Abstract
Apparatus and methods are disclosed related to phase synchronization in transmitters. One such apparatus includes a wireless transmitter with two or more separate and unrelated local oscillators. The apparatus can provide RF signals to multiple antenna elements, which can be implemented in systems such as beamforming systems or multiple input multiple output (MIMO) systems. A phase difference between local oscillators is determined using outputs of receivers. The phase difference can be used to adjust a phase of signals associated with one or more of the local oscillators, such that the phase of each signal provided to the multiple antenna elements can be aligned.
Claims22
An apparatus comprising:
- a first integrated circuit comprising:
- a local oscillator configured to generate a local oscillator output signal;
- a transmit path having a phase control input, the transmit path being configured to receive the local oscillator output signal as an input, to generate a first radio frequency (RF) output signal based at least partly on the local oscillator output signal, and to provide the first RF output as an output of the first integrated circuit, wherein a phase of the first RF output signal is controllable based at least partly on a control input provided to the phase control input;
- and
- a receive path configured to receive the local oscillator output signal and a receive signal as inputs, wherein an input of the first integrated circuit is configured to receive the receive signal, wherein the receive signal is RF sampled from a second RF output signal having a phase component that is independent of the phase of the first RF signal, wherein the receive path is configured to generate a signal having a phase component that includes a relative phase difference between the first RF signal and the second RF signal as an output.
2 more elements
An apparatus comprising:
- a local oscillator configured to generate a local oscillator output signal;
- a transmit path having a phase control input, the transmit path being configured to receive the local oscillator output signal as an input and to generate a first radio frequency (RF) output signal based at least partly on the local oscillator output signal, wherein a phase of the first RF output signal is controllable based at least partly on a control input provided to the phase control input;
- a receive path configured to receive the local oscillator output signal and a receive signal as inputs, wherein the receive signal is RF sampled from a second RF output signal, wherein the receive path is configured to generate a signal having a phase component that includes a relative phase difference between the first RF signal and the second RF signal as an output;
- a first directional coupler coupled to the first RF output signal, wherein the first directional coupler is configured to generate a second receive signal;
- a second directional coupler coupled to a second RF output signal, wherein the second directional coupler is configured to generate the receive signal for the receive path;
- a second local oscillator separate from the local oscillator, wherein the second local oscillator is configured to generate a second local oscillator output signal;
- a second transmit path configured to receive the second local oscillator output signal as an input and to generate the second RF output signal based at least partly on the second local oscillator output signal;
- and
- a second receive path configured to receive the second local oscillator output signal and the second receive signal as inputs, wherein the second receive path is configured to generate an output signal having a phase component that includes a relative phase difference between the second local oscillator output signal and the second receive signal.
6 more elements
An apparatus comprising:
- a local oscillator configured to generate a local oscillator output signal;
- a transmit path having a phase control input, the transmit path being configured to receive the local oscillator output signal as an input and to generate a first radio frequency (RF) output signal based at least partly on the local oscillator output signal, wherein a phase of the first RF output signal is controllable based at least partly on a control input provided to the phase control input;
- a receive path configured to receive the local oscillator output signal and a receive signal as inputs, wherein the receive signal is RF sampled from a second RF output signal, wherein the receive path is configured to generate a signal having a phase component that includes a relative phase difference between the first RF signal and the second RF signal as an output;
- a first directional coupler coupled to the first RF output signal, wherein the first directional coupler is configured to generate a second receive signal;
- an N-th directional coupler coupled to an N-th RF output signal, wherein the N-th directional coupler is configured to generate the receive signal for the receive path;
- an N-th local oscillator separate from the local oscillator, wherein the N-th local oscillator is configured to generate an N-th local oscillator output signal;
- an N-th transmit path configured to receive the N-th local oscillator output signal as an input and to generate the N-th RF output signal based at least partly on the N-th local oscillator output signal;
- and
- an N-th receive path configured to receive the N-th local oscillator output signal and an N-th receive signal as inputs, wherein the N-th receive signal is not the second receive signal, wherein the receive path is configured to generate an output signal having a phase component that includes relative phase difference between the N-th local oscillator output signal and the N-th receive signal.
6 more elements
A method of deriving a relative phase difference, the method comprising:
- generating a first RF signal in a transmission path based at least partly on a first local oscillator output signal;
- providing an RF sample of the first RF signal to a receive path using a directional coupler;
- generating a first baseband signal in the receive path based at least partly on the RF sample of the first RF signal and a second local oscillator output signal, wherein the second local oscillator output signal and the first, local oscillator output signal are generated from separate local oscillators;
- generating a second RF signal in a second transmission path based at least partly on the second local oscillator output signal;
- providing an RF sample of the second RF signal to a second receive path using a second directional coupler;
- and
- generating a second baseband signal in the second receive path based at least partly on the RF sample of the second RF signal;
- deriving, using a processor, a relative phase difference between the first local oscillator output and the second local oscillator output based at least partly on the first baseband signal and the second baseband signal.
5 more elements
An apparatus comprising:
- a local oscillator configured to generate a local oscillator output signal;
- means for transmitting an RF signal having means for controlling a phase of the RF signal and means for upconverting a baseband signal to RF based at least partly on the local oscillator input;
- means for receiving a second RF signal having means for generating a signal with a phase component that includes a relative phase difference between the RF signal and the second RF signal;
- and
- antenna elements comprising a first antenna element associated with the first RF signal and a second antenna element associated with the second RF signal, wherein the antenna elements are configured to generate a directional beam in a selected direction based at least partly on the phase of the RF signal and a second phase of the second RF signal.
2 more elements
Dependencies are inferred from the claim text.