Patent ID: 8610512

Claim:
An apparatus comprising a synthesizer for synthesizing a synthesized signal oscillating at a synthesized-signal frequency, said synthesizer comprising a first frequency-synthesizing stage configured for generating, at an output terminal thereof, an intermediate signal oscillating at an intermediate frequency, said first frequency-synthesizing stage comprising a phase-locked loop, a rendering terminal for rendering said synthesized signal, a second frequency-synthesizing stage comprising a radio-frequency oscillator, said radio-frequency oscillator comprising a magnetoresistive device within which there flows a spin-polarized electrical current to generate said synthesized signal on an output electrode connected to said rendering terminal, said magnetoresistive device being formed by a stack of magnetic and non-magnetic layers, a synchronization terminal for synchronizing said frequency of said synthesized signal with said frequency of said signal received at said synchronization terminal, said synchronization terminal being connected to said output terminal of said first frequency-synthesizing stage to receive said intermediate signal, and at least one of a current source to cause a continuous current of electrons to flow perpendicularly through said layers and a magnetic field generator capable of generating a continuous magnetic field having field lines that cross a free layer of said magnetoresistive device with an intensity greater than or equal to 1 oersted, said at least one of a current source and a magnetic field generator being set so that said radio-frequency oscillator oscillates at a scaled frequency when said oscillator is synchronized with said intermediate signal, said scaled frequency being said intermediate frequency scaled by a scaling factor that is a positive rational number different from 1 such that said scaled frequency is equal to said synthesized-signal frequency, and at a free frequency within ±60% of being equal to said synthesized-signal frequency in the absence of a signal at said synchronization terminal of said radio-frequency oscillator.