Phase Shifters, Interrogators, Methods Of Shifting A Phase Angle Of A Signal, And Methods Of Operating An Interrogator
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Accused Products
Abstract
The present invention includes phase shifters, interrogators, methods of shifting a phase angle of a signal, and methods of operating an interrogator. One aspect of the present invention provides a phase shifter including a first power divider configured to receive a signal and provide plural quadrature components of the signal; plural mixers coupled with the first power divider and configured to scale the quadrature components using a phase shift angle; and a second power divider coupled with the mixers and configured to combine the scaled quadrature components to shift the phase angle of the input signal by the phase shift angle.
93 Citations
67 Claims
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1-41. -41. (canceled)
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42. A method for minimizing a transmitted continuous-wave (CW) signal that appears within a received backscatter signal, comprising:
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adjusting an amplitude of a local CW signal using a variable attenuator to create an amplitude-adjusted local signal, wherein the local CW signal corresponds to the transmitted CW signal;
adjusting a phase of the amplitude-adjusted local signal using a phase shifter to create an adjusted local signal;
computing an amplitude control signal based upon an amplitude of the adjusted local signal and an amplitude of the received backscatter signal;
controlling the variable attenuator using the amplitude control signal;
summing the adjusted local signal and the received backscatter signal to create a summed signal; and
providing the summed signal to processing circuitry. - View Dependent Claims (43, 44, 45, 46, 47, 48, 49, 50)
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51. A method for minimizing transmitted signal bleed-through in a radio frequency identification (RFID) interrogator, comprising:
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providing a local continuous-wave (CW) signal to a variable attenuator;
providing an amplitude-adjusted local CW signal from the variable attenuator to a phase shifter;
providing an adjusted local CW signal from the phase shifter to a first amplitude detector;
providing a first amplitude signal from the first amplitude detector to an amplitude adjuster;
providing a return link communication from an RFID tag to a second amplitude detector;
providing a second amplitude signal from the second amplitude detector to the amplitude adjuster;
comparing, in the amplitude adjuster, an amplitude of the adjusted local CW signal and an amplitude of the return link communication;
providing an amplitude control signal from the amplitude adjuster to the variable attenuator;
providing the adjusted local CW signal to a first coupler;
providing the return link communication to the first coupler;
summing, in the first coupler, the adjusted local CW signal and the return link communication to create a summed signal;
providing the summed signal to a low noise amplifier (LNA);
providing the summed signal to a third amplitude detector;
providing a third amplitude signal from the third amplitude detector to a phase adjuster;
providing a signal from the amplitude adjuster to the phase adjuster indicating that the amplitudes of the adjusted local CW signal and the return link communication have been matched;
selecting, at the phase adjuster, a selected phase shift for the amplitude-adjusted local CW signal; and
providing a phase control signal from the phase adjuster to the phase shifter to implement the selected phase shift. - View Dependent Claims (52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67)
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Specification