Media noise and signal-to-noise ratio estimates for high areal density recording

Abstract

Transition jitter, σjitter, and pulse-width fluctuations, σPW50, limit the attainable signal-to-noise ratio (SNR) in a magnetic recording system. We estimate the media noise power for systems with high areal density. The case of a Lorentzian-shaped voltage pulse is worked out in detail. Experiments show that the model reasonably reproduces data. The analysis is applied to areal densities of 10 Gbit/in.2 and beyond. If the ratio of PW50 to bit length B (the so-called channel density U) is kept constant, the ratio σjitter/B is found to depend only on SNR and U, and is about 3% for SNR=26 dB, at any density. Under those assumptions, σjitter≈0.75 nm at 1 Mfci. Otherwise, for constant PW50, σjitter/B decreases monotonically with density, and is about 1% for PW50=120 nm, 1/B=1 Mfci, SNR=27 dB.