APPARATUS AND METHOD FOR PHASE SYNCHRONIZATION IN RADIO FREQUENCY TRANSMITTERS
First Claim
1. 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; and
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.
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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.
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Citations
23 Claims
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1. An apparatus comprising:
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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; and 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method comprising:
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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; 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. - View Dependent Claims (18, 19, 20, 21, 22)
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23. An apparatus comprising:
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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; and 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.
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Specification