An adaptive analog noise-predictive decision-feedback equalizer

In this paper, an adaptive noise-predictive decision-feedback equalizer (NPDFE) is presented. The NPDFE architecture and its implementation are described. The NPDFE consists of an analog finite-impulse-response (FIR) forward equalizer, a recursive analog equalizer for noise prediction, and a decision-feedback equalizer (DFE). The recursive equalizer reduces noise enhancement and improves the signal-to-noise ratio (SNR) at the decision slicer input. The prototype targets a magnetic recording channel modeled by a Lorentzian impulse response. Measured results show that compared to a conventional DFE with FIR forward equalizer, the NPDFE achieves a SNR improvement of about 2 dB with PW₅₀=2.5T. The NPDFE consumes 130 mW at a data rate of 100 Mb/s and occupies 1.3 mm² of die area in a 0.5-μm CMOS process