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

An apparatus for implementing data detection with spin-torque oscillator (STO) sensing for hard disk drives comprising:

• a spin-torque oscillator (STO) read sensor sensing a signal magnetic field and producing a readback signal having an oscillation frequency ω(t);
• a demodulator including
• a pair of mixers coupled to a quadrature reference oscillator mixing a received input signal from said STO read sensor with respective quadrature signal components cos(ω0t), and sin(ω0t) to form signals at the sum and difference frequencies, ω±ω0;
• and
• a respective lowpass filter receiving and lowpass filtering mixer signals to remove the sum frequency components for providing a demodulator output signal proportional the STO oscillation frequency ω(t), said demodulator output signal being used for processing by data detection electronics;
• and
• a respective differentiation circuit receiving a resulting modulated signal from said respective lowpass filters and providing resulting differentiated signals.

A system for implementing data detection with spin-torque oscillator (STO) sensing for hard disk drives comprising:

• a media generating a magnetic signal having an amplitude determined by media field strength;
• a spin-torque oscillator (STO) read sensor sensing said magnetic signal generated by said media and producing a readback signal having an oscillation frequency ω(t);
• a demodulator including
• a pair of mixers coupled to a quadrature reference oscillator mixing a received input signal from said STO read sensor with respective quadrature signal components cos(ω0t), and sin(ω0t) to form signals at the sum and difference frequencies, ω±ω0;
• and
• a respective lowpass filter receiving and lowpass filtering mixer signals to remove the sum frequency components for providing a demodulator output signal proportional the STO oscillation frequency ω(t), said demodulator output signal being used for processing by data detection electronics;
• a respective differentiation circuit receiving a resulting modulated signal from said respective lowpass filters and providing resulting differentiated signals;
• and
• a second pair of mixers coupled to said respective lowpass filters and said respective differentiation circuits, for mixing said resulting modulated signal from said respective lowpass filters and said resulting differentiated signals from said respective differentiation circuits.