Implementing spin-torque oscillator sensing with enhanced integrated demodulator for hard disk drives

摘要

A method, apparatus, and system are provided for implementing spin-torque oscillator sensing with an enhanced integrated demodulator for hard disk drives. The demodulator receives an input signal from a STO read sensor having an oscillation frequency omega related to the strength of the detected magnetic signal field. The demodulator includes a pair of mixers coupled to a quadrature reference oscillator with respective quadrature components cos(omega0t), and sin(omega0t) of the quadrature reference oscillator being mixed with a received input signal to form signals at the sum and difference frequencies, omega±omega0. Each of these mixer products is lowpass filtered by a respective a lowpass filter to remove the sum frequency components for providing a demodulator output signal that is directly proportional the STO oscillation frequency omega. The demodulator output signal is used for processing by data detection electronics.