Asymmetry correction for a read head
First Claim
1. An asymmetry correction circuit for generating an output signal from an asymmetric input signal, the asymmetric input signal being produced by a magneto-resistive head, the circuit comprising:
- an input stage receiving an asymmetric input signal and generating an output signal at an output, the input stage having a subtraction terminal; and
a squaring circuit having a modulation stage, the squaring circuit having an input connected to the output of the input stage to receive the output signal and having an output connected to the modulation stage and to the subtraction terminal of the input stage to provide a modulated squared output signal to the subtraction terminal for subtraction from the asymmetric input signal.
2 Assignments
0 Petitions
Accused Products
Abstract
A method and a circuit for correcting asymmetry in a response signal generated by a magneto-resistive head. The magneto-resistive head generates a response signal to transmit digital information read from a magnetic media storage device. The asymmetry is corrected in a negative feedback manner by squaring an output signal, modulating the squared output signal, and subtracting the modulated squared output signal from the response signal to generate the output signal. The circuit employs a differential amplifier as an input stage and a Gilbert multiplier circuit to square the output signal.
75 Citations
38 Claims
-
1. An asymmetry correction circuit for generating an output signal from an asymmetric input signal, the asymmetric input signal being produced by a magneto-resistive head, the circuit comprising:
-
an input stage receiving an asymmetric input signal and generating an output signal at an output, the input stage having a subtraction terminal; and a squaring circuit having a modulation stage, the squaring circuit having an input connected to the output of the input stage to receive the output signal and having an output connected to the modulation stage and to the subtraction terminal of the input stage to provide a modulated squared output signal to the subtraction terminal for subtraction from the asymmetric input signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. An asymmetry correction circuit for generating an output signal from an asymmetric input signal produced by a magneto-resistive head, comprising:
-
a multiplier circuit having a plurality of input terminals, an output terminal, and a modulation element; and an amplifier having an input and an output, the output of the amplifier being connected to the input terminals of the multiplier circuit to square the output signal by multiplying the output signal by itself, the output of the amplifier being connected to a circuit output port, the amplifier further having a subtraction terminal connected to the output terminal of the multiplier circuit to receive a modulated squared output signal from the modulation element. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
-
-
22. A system for reading data from a storage media and generating an information signal, comprising:
-
a read head reading data from the storage media and generating a first signal in response to the data; a pre-amplifier receiving the first signal and amplifying the first signal to generate a second signal; a voltage controlled amplifier receiving the second signal and amplifying the second signal to generate a third signal; a register storing a calibration value; a digital-to-analog converter connected to the register to receive the calibration value, the digital-to-analog converter generating a calibration signal based on the calibration value; an asymmetry correction circuit receiving the third signal and the calibration signal and correcting an asymmetry in the third signal according to the calibration signal to generate a fourth signal; a filter receiving the fourth signal and filtering the fourth signal to generate a fifth signal; and a digital signal processing circuit receiving the fifth signal and processing the fifth signal into the information signal. - View Dependent Claims (23)
-
-
24. A method for generating an output signal from an asymmetric input signal produced by a magneto-resistive head, the asymmetric input signal having positive peaks and negative peaks, the method comprising:
-
squaring the output signal by multiplying the output signal with itself in a multiplier circuit to obtain a squared output signal; generating a modulated signal by multiplying the squared output signal by a selected ratio in a modulating circuit; and subtracting the modulated signal from the asymmetric input signal to generate the output signal. - View Dependent Claims (25, 26, 27, 28)
-
-
29. A method comprising:
-
providing an asymmetric input signal produced by a magneto-resistive head, the asymmetric input signal having positive and negative peaks; subtracting a modulated signal from the input signal to generate a first signal; generating a squared first signal by multiplying the first signal with itself; and modulating the squared first signal according to a selected ratio to generate the modulated signal. - View Dependent Claims (30, 31, 32, 33)
-
-
34. A method for reading data from a storage media with a plurality of read heads to generate an information signal, comprising:
-
selecting a first read head; storing a first calibration value for the first read head in a register; reading data from the storage media with the first read head and generating a first signal from the first read head in response to the data; amplifying the first signal to generate a second signal; subtracting a first modulated signal from the second signal to generate a third signal; generating a squared third signal by multiplying the third signal with itself; modulating the squared third signal according to the first calibration value to generate the first modulated signal; filtering the third signal to generate a fourth signal; and processing the fourth signal to generate the information signal. - View Dependent Claims (35)
-
-
36. A method comprising:
-
subtracting a modulated signal from an input signal to generate a first signal; generating a squared first signal by multiplying the first signal with itself; and modulating the squared first signal by a selected ratio to generate the modulated signal, wherein modulating the squared first signal comprises selecting an impedance value in a Gilbert multiplier circuit.
-
-
37. A method comprising:
-
subtracting a modulated signal from an input signal to generate a first signal; generating a squared first signal by multiplying the first signal with itself; and modulating the squared first signal by a selected ratio to generate the modulated signal, wherein modulating the squared first signal comprises regulating one or more variable current sources dynamically with a control logic circuit.
-
-
38. A method comprising:
-
subtracting a modulated signal from an input signal to generate a first signal; generating a squared first signal by multiplying the first signal with itself; and modulating the squared first signal by a selected ratio to generate the modulated signal, wherein modulating the squared first signal comprises selecting a current generated by each of a plurality of controlled current generators in a Gilbert multiplier circuit.
-
Specification