Automatic Gain Control Early Acquisition Circuit
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Solution Overview
Problem
Magnetic storage systems face performance degradation due to residual gain errors at the end of the gain acquisition stage, which is exacerbated by the short acquisition length of typical gain loops.
Innovation Solution
An automatic gain control circuit with early acquisition performs Zero Gain Start (ZGS) calculations and gain loop adjustments in parallel, using multiple techniques to correct gain errors in a variable gain amplifier, with the ZGS calculation and early gain acquisition determining the initial configuration for subsequent stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the gain loop acquisition length is kept short, then the gain loop can complete acquisition quickly, but residual gain errors remain at the end of the gain acquisition stage degrading read channel performance
Solution Approach 1:
The patent performs preliminary gain corrections during an early gain acquisition period before the main gain acquisition stage. A gain loop calculates early gain corrections based on early data samples, and these corrections are applied in advance to reduce residual gain errors that would otherwise degrade read channel performance. This preliminary action allows the main gain acquisition to complete quickly while ensuring high reliability.
2Measurement precision
If multiple gain correction techniques are used in parallel, then gain correction accuracy is improved, but device complexity increases
Solution Approach 1:
The patent segments the gain correction process into two distinct parallel techniques: (1) a Zero Gain Start calculation that identifies large gain distortions, and (2) a gain loop that performs early gain acquisition to correct smaller gain distortions. Each segment handles a specific range of correction needs, and their results are combined to achieve high accuracy without requiring a single overly complex correction mechanism.
Solution Approach 2:
The patent merges the results from two parallel gain correction techniques by selecting the appropriate correction value based on which technique provides the better correction for the current conditions. The gain correction selector circuit combines the ZGS calculation result and the early gain acquisition result to determine the final gain correction value, achieving high accuracy through intelligent combination of multiple simpler techniques.
Data Source
AI summary
A system for accessing a data from a storage device includes a gain value calculation circuit operable to calculate a first gain value based upon a data set, an early gain acquisition circuit operable to generate a second gain value in parallel to calculation of the first gain value by the gain value calculation circuit, and a gain combination circuit operable to combine the first gain value and the second gain value to yield a third gain value.