Write Transducer Impedance Segmentation for Magnetic Storage
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Solution Overview
Problem
The current magnetic storage systems face limitations in data rate during writing operations due to impedance mismatching between the write driver circuit and the cable, which results in slower current rise times, making it difficult to match the output impedance of the write driver with the characteristic impedance of the cable.
Innovation Solution
The solution involves splitting the write signal generator impedance into two components, with one part remaining on the circuit board and the other near the write transducer, allowing for better matching of the impedance between the write signal generator circuit and the cable, while maintaining the steady-state current level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output impedance of the write driver is changed to match the characteristic impedance of the cable, then impedance matching is improved, but the steady state current required for optimal magnetic patterns cannot be maintained
Solution Approach 1:
The write driver output impedance is segmented into two separate impedance elements: one impedance element remains in the write driver circuit on the circuit board, and another impedance element is placed near the write transducer. This segmentation allows each impedance element to contribute to overall impedance matching with the cable while preserving the required steady state current flow through the write transducer.
Solution Approach 2:
An intermediary impedance element is introduced between the write driver and the cable connection point. This intermediary component acts as a mediator that facilitates impedance matching between the write driver circuit and the cable, reducing reflections without directly altering the steady state current characteristics of the write transducer.
2Reliability
If the cable conductor width and spacing are adjusted to achieve impedance matching, then characteristic impedance is improved, but cable flexibility and fabrication constraints are violated
Solution Approach 1:
The impedance matching function is extracted from the cable structure itself and relocated to discrete impedance elements that are placed at specific locations in the circuit. This extraction allows the cable to maintain its original flexible structure and standard fabrication processes while achieving impedance matching through the added impedance components.
3Reliability
If the write signal generator is moved proximate to the head, then cable impedance effects are eliminated, but cable complexity and driver complexity increase
Solution Approach 1:
An intermediary impedance element is placed at a strategic location between the write driver and the cable connection point. This intermediary component provides impedance matching without requiring the write signal generator to be physically relocated, thereby avoiding the added complexity in cabling and driver design that would result from moving the signal generator proximate to the head.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances impedance matching, reducing reflections and enabling faster current rise times, thus improving data rate and storage performance without altering the steady-state current.
Implementation Method 1
the current rise time in the inductive coil of the writer
Implementation Method 2
impedance mismatching between the output impedance of the write driver and the characteristic impedance of the cable
Data Source
AI summary
A magnetic, head in one embodiment includes a substrate; a write transducer; leads coupled to the write transducer; and a resistor coupled between one of the leads and the substrate or a common line. A magnetic storage system in another embodiment includes a cable having a characteristic impedance associated with a pair of conductors; a write signal generator coupled to the pair of conductors; at least one first device coupled to the cable in series with the write signal generator and at least one of the cable conductors, the at least one first device providing a first impedance; at least one second device providing a second impedance and coupled to a second end of the cable in series with at least one of the cable conductors and the first device; and a head having a write transducer coupled to the at least one second device.