Magneto-resistive asymmetry compensation loop
AssigneeInfineon Technologies North America Corp.
InventorsJonathan Ashley, James Wilson Rae, Stephen J. Franck
Life of this patent
Estimating the term…
Abstract
A magneto-resistive asymmetry compensation system includes a linearizer (61) interposed in a data path and a control loop (63). The control loop uses signal estimates from an interpolated timing response unit (25) to derive a magneto-resistive asymmetry error. The error term is used to obtain a control scaling input to the linearizer. The linearizer functions to multiply the scaling multiple to the square of the input signal and then add it back to the input signal.
Claims13
A magneto-resistive asymmetry correction circuit, comprising:
- a magneto-resistive linearizer circuit adapted to receive an input from an amplifier, said magneto-resistive linearizer being designed to compensate for magneto-resistive asymmetry in a sampled amplitude read channel;
- and
- a control circuit for providing a control input to said magneto-resistive linearizer circuit, said control circuit adapted to receive as inputs a plurality of signal estimates unit;
- wherein said control circuit determines a magneto-resistive assymetry error term whose computation depends on a plurality of successive signal estimates, said plurality of successive signal estimates being derived from said plurality of signal estimates, said magneto-resistive assymetry error term being used to obtain said control input to said magneto-resistive linearizer circuit.
A magneto-resistive asymmetry correction circuit, comprising:
- a magneto-resistive linearizer circuit adapted to receive an input from an amplifier;
- and
- a control circuit providing an input to said magneto-resistive linearizer circuit, said control circuit receiving as inputs a plurality of signal estimates, said control circuit including
- a sample rate reducer;
- an error estimator, said error estimator adapted to estimate a magneto-resistive asymmetry error;
- and
- a state machine defined substantially as follows:
- −4 −3 −2 −1 0 1 2 3 −2 −2/−4 −2/−3 0/−4 0/−3 0/−2 0/−1 0/0 0/1 −1 −1/−4 −1/−3 0/−3 0/−2 0/−1 0/0 0/1 0/2 0 0/−4 0/−3 0/−2 0/−1 0/1 0/1 0/2 0/3 1 0/−3 0/−2 0/−1 0/−0 0/1 0/2 1/2 1/3 2 0/−2 0/−1 0/0 0/1 0/2 0/3 2/2 3/3
- wherein rows correspond to five possible values of an input signal esac(2k), and columns correspond to eight possible values of a state variable σ2k;
- and
- entries are of the form f2k/σ2k+2, where f2k is the output and σ2k+2 is the next state.
A sampled amplitude read channel comprising
- means for receiving encoded data;
- and
- a magneto-resistive asymmetry loop, said magneto-resistive asymmetry loop including:
- a magneto-resistive linearizer circuit adapted to receive an input from an amplifier, said magneto-resistive linearizer being designed to compensate for magneto-resistive asymmetry in a sampled amplitude read channel;
- and
- a control circuit providing a control input to said magneto-resistive linearizer circuit, said control circuit receiving as inputs a plurality of signal estimates timing response unit, wherein said control circuit determines a magneto-resistive assymetry error term whose computation depends on a plurality of successive signal estimates, said plurality of successive signal estimates being derived from said plurality of signal estimates, said magneto-resistive assymetry error term being used to obtain said control input to said magneto-resistive linearizer circuit.
Dependencies are inferred from the claim text.