Automatic gain control loop adaptation for enhanced nyquist data pattern detection

An apparatus, comprising:

• read channel circuitry;
• and
• signal processing circuitry associated with the read channel circuitry, the signal processing circuitry comprising:
• an amplifier, the amplifier being configured to receive and amplify an input signal received by the read channel circuitry;
• a detector operatively coupled to the amplifier, the detector being configured to detect a data pattern from the amplified input signal;
• an analog-to-digital converter operatively coupled between the amplifier and the detector, the analog-to-digital converter being configured to sample and quantize the amplified input signal to generate a quantized digital signal;
• a feedback path operatively coupled between the detector and the amplifier, the feedback path being configured to provide a feedback signal to the amplifier to adjust a gain of the amplifier, wherein the feedback path generates the feedback signal in accordance with a value selected to improve detection of the data pattern by increasing an amplitude of the data pattern around a given frequency;
• wherein the feedback path further comprises a scalar multiplier operatively coupled to the detector and configured to multiply the value, which is a scalar, with a detected digital signal generated by the detector responsive to the quantized digital signal, wherein the detected digital signal represents the data pattern.

A method comprising the steps of:

• amplifying an input signal;
• detecting a data pattern from the amplified input signal to generate a detected digital signal representing the data pattern;
• generating a feedback signal to adjust a gain of the amplified signal, wherein the feedback signal is generated in accordance with a value selected to improve detection of the data pattern by increasing an amplitude of the data pattern around a given frequency;
• wherein generating the feedback signal comprises multiplying the value with the detected digital signal.

A method comprising the steps of:

• amplifying an input signal;
• detecting a data pattern from the amplified input signal;
• generating a feedback signal to adjust a gain of the amplified signal, wherein the feedback signal is generated in accordance with a value selected to improve detection of the data pattern by increasing an amplitude of the data pattern around a given frequency;
• sampling and quantizing the amplified input signal to generate a quantized digital signal;
• and
• multiplying the value with a detected digital signal generated responsive to the quantized digital signal, wherein the detected digital signal represents the data pattern.

An apparatus comprising:

• an amplifier, the amplifier being configured to receive and amplify an input signal;
• a detector operatively coupled to the amplifier, the detector being configured to detect a data pattern from the amplified input signal and to generate a detected digital signal representing the data pattern;
• and
• a feedback path operatively coupled between the detector and the amplifier, the feedback path being configured to provide a feedback signal to the amplifier to adjust a gain of the amplifier, wherein the feedback path generates the feedback signal in accordance with a value selected to improve detection of the data pattern by increasing an amplitude of the data pattern around a given frequency.
• wherein the feedback path further comprises a multiplier operatively coupled to the detector and configured to multiply the value with the detected digital signal.