Patent ID: 8655302
Filing Date: 2014-02-18
Classification: H03B,H03D

Abstract:
1. An apparatus comprising a demodulator of an electrical signal frequency-modulated about a carrier frequency with a modulation frequency, said demodulator comprising an acquisition terminal for receiving the frequency-modulated signal, a rendering terminal for rendering the frequency-demodulated electrical signal, a radiofrequency oscillator comprising a magnetoresistive device within which there flows a spin-polarized electrical current to produce an oscillating signal at an output electrode, the magnetoresistive device being formed by a stack of magnetic layers and non-magnetic layers, the layers having a resistance whose amplitude varies as a function of frequency of the oscillating signal at the output electrode, 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 configured for generating a continuous magnetic field, field lines of which cross a free layer of the magnetoresistive device with an intensity greater than or equal to 1 Oersted, the at least one of a current source and a continuous magnetic field generator being set so that, under identical conditions of operation, the radiofrequency oscillator is synchronized with oscillations at a first frequency and, in alternation, with oscillations at a second frequency, where the first and second frequencies are used in the frequency-modulated signal to encode respective pieces of information, and a synchronization terminal for synchronizing the frequency of the oscillating signal with the frequency of the signal received at the synchronization terminal, the synchronization terminal being connected to the acquisition terminal, and a low-pass filter having a −3 dB cut-off frequency that is strictly lower than the carrier frequency and higher than the modulation frequency, said low-pass filter being connected to the output electrode of the magnetoresistive device to filter the oscillating signal, and to the rendering terminal to provide, as a demodulated electrical signal, the filtered signal, the low-pass filter.