Stepped Impedance Flexure Trace Array for Linear Group Delay
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Solution Overview
Problem
Disk drive flexures experience signal distortion due to non-linear group delay, leading to unstable frequency response and data loss, as existing designs fail to maintain a constant phase change with frequency across operational ranges.
Innovation Solution
A method for forming a trace array with alternating high and low impedance elements, where the length of each trace segment is set based on measured phase constants to achieve a linear group delay response across the operational frequency range, utilizing inductors and capacitors as filter circuit elements and varying trace widths to mimic impedance sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional uniform impedance trace design is used, then manufacturing is simple, but signal distortion occurs due to non-linear group delay
Solution Approach 1:
The trace is divided into multiple trace segments with alternating high and low impedance values. Each segment corresponds to a discrete impedance element in a filter circuit, allowing the trace to function as a distributed filter that compensates for non-linear group delay and achieves linear phase response across the operational frequency range.
Solution Approach 2:
Different portions of the trace are assigned different impedance characteristics (high or low) to create localized impedance variations. This non-uniform impedance distribution along the trace length enables selective frequency response control, transforming the trace from a simple conductor into an active signal conditioning element that corrects phase distortion.
2Reliability
If trace length is increased to improve signal stability, then frequency response stability improves, but data transmission speed decreases
Solution Approach 1:
The impedance values of trace segments are specifically designed to alternate between high and low values, creating a stepped impedance profile. This parameter variation along the trace transforms it into a distributed filter network that provides linear phase response and stable frequency characteristics without requiring excessive trace length, thereby maintaining data transmission speed.
Data Source
AI summary
Various embodiments concern a method for forming a trace array by modeling a trace array having a plurality of traces, each trace having a plurality of trace segments corresponding to elements of a filter circuit having alternating high and low impedance elements. The alternating high and low impedance elements can correspond to inductors and capacitors. For each trace segment, a delay constant is measured between a plurality of nodes that are longitudinally arrayed along the trace segment. The delay constant can be a phase delay. The length of each trace segment is set based on the delay constant of the trace segment. The length of each trace segment can be set such that the trace has a linear group delay response across an operational frequency range of the flexure. A trace array is then formed based on the set lengths.