Oscillation detector

An apparatus comprising a detector of oscillations in a frequency band around a first frequency in a received radio-frequency electrical signal, said detector comprising an acquisition terminal for receiving said radio-frequency electrical signal, and a radio-frequency oscillator to be synchronized with said first frequency, said radio-frequency oscillator comprising at least one magnetoresistive device within which flows a spin-polarized electrical current for generating an oscillating signal at an output electrode, said at least one magnetoresistive device being formed by a stack of magnetic and non-magnetic layers, a synchronization terminal for synchronizing a frequency of said oscillating signal with a frequency of a signal received at said synchronization terminal, said synchronization terminal being connected to said acquisition terminal, and at least one of a current source to cause a continuous current of electrons to flow perpendicularly through said layers and a continuous magnetic field generator, said at least one said current and said continuous magnetic field being configured so that a free frequency of oscillations of an oscillating signal produced in absence of a signal at said synchronization terminal is, within ±60%, equal to said first frequency scaled by a positive rational number, an electronic comparator capable of automatically distinguishing a synchronized state of said radio-frequency oscillator from a non-synchronized state of said radio-frequency oscillator on the basis of an oscillating signal produced by said radio-frequency oscillator, said synchronized state being a state in which a power level of low-frequency components of said oscillating signal produced by said radio-frequency oscillator is below a predetermined power threshold, and said non-synchronized state being a state in which a power level of said low-frequency components of said oscillating signal produced by said radio-frequency oscillator is above said predetermined power threshold, said low-frequency components consisting of components having a frequency below 1 gigahertz, and indicating presence of oscillations in said frequency band around said frequency in said received radio-frequency electrical signal when said oscillator is in said synchronized state, and indicating absence of oscillations in said frequency band in said received radio-frequency electrical signal otherwise.

A method for detecting oscillations in a frequency band around a first frequency in a received radio-frequency electrical signal, said method comprising receiving said radio-frequency signal at a synchronization terminal of a radio-frequency oscillator configured to be synchronized with said first frequency, said radio-frequency oscillator comprising a magnetoresistive device within which there flows a spin-polarized electrical current to generate an oscillating signal at an output electrode, said magnetoresistive device being formed by a stack of magnetic and non-magnetic layers, at least one of a current source to cause a continuous current of electrons to flow in said layers in a direction perpendicular to said layers and a continuous magnetic field generator, at least one of said continuous current of electrons and said continuous magnetic field being set so that a free frequency of oscillations of said oscillating signal produced in absence of a signal at said synchronization terminal is within ±60% of being equal to said first frequency scaled by a positive rational number, automatically distinguishing a synchronized state of said radio-frequency oscillator from a non-synchronized state of said radio-frequency oscillator based at least in part on an oscillating signal produced by said radio-frequency oscillator, said synchronized state being a state in which a power-level of low-frequency components of said oscillating signal produced by said radio-frequency oscillator is below a predetermined power threshold, and said non-synchronized state being a state in which a power-level of said low-frequency components of said oscillating signal produced by said radio-frequency oscillator is above said predetermined power threshold, said low-frequency components consisting of components having a frequency below 1 gigahertz, and indicating presence of oscillation in said frequency band around said first frequency in response to detection of said synchronized state and, alternatively, indicating absence of oscillation in said frequency band otherwise.