Disk Drive Preamplifier Common Lead System for Multiple Readers
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Solution Overview
Problem
In magnetic disk drives with multiple read heads, the existing designs face challenges in minimizing area and power requirements due to the need for multiple electrical paths and independent differential amplifiers, leading to skew and fly-height control issues, as well as increased space and power consumption.
Innovation Solution
A common lead system is implemented in the slider, suspension, and preamplifier, using four signal traces to connect multiple read transducers with a shared signal return lead, reducing the number of electrical paths and power consumption, and employing single-ended or pseudo-single-ended amplifier designs to achieve compact and efficient connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple independent differential amplifiers are used for multiple read heads, then each reader can be independently amplified, but the layout area and power consumption increase significantly
Solution Approach 1:
The patent merges multiple independent differential amplifiers into a single preamplifier that handles multiple readers. The preamplifier uses a shared differential pair of transistors (first and second transistors) that can simultaneously amplify signals from multiple read heads through common lead connections, reducing the layout area while maintaining signal amplification quality.
Solution Approach 2:
The preamplifier is designed with multi-functionality to serve multiple readers simultaneously. The single preamplifier unit can amplify signals from multiple read heads by using common lead connections and a shared differential pair, making one amplifier unit perform the function that previously required multiple separate amplifiers.
2Reliability
If multiple independent differential amplifiers are used for multiple read heads, then each reader can be independently amplified, but power consumption increases
Solution Approach 1:
The patent merges multiple independent differential amplifiers into a single preamplifier that handles multiple readers. The preamplifier uses a shared differential pair of transistors (first and second transistors) that can simultaneously amplify signals from multiple read heads through common lead connections, reducing the layout area while maintaining signal amplification quality.
Solution Approach 2:
The preamplifier is designed with multi-functionality to serve multiple readers simultaneously. The single preamplifier unit can amplify signals from multiple read heads by using common lead connections and a shared differential pair, making one amplifier unit perform the function that previously required multiple separate amplifiers.
3Reliability
If multiple electrical paths are used to connect multiple readers, then each reader can have dedicated connections, but the number of traces and complexity increase
Solution Approach 1:
The patent merges multiple electrical paths into a reduced set of common leads. Instead of having separate dedicated traces for each reader, the invention uses common lead connections that multiple readers share, reducing the total number of traces while maintaining reliable signal transmission through the preamplifier's differential pair architecture.
Solution Approach 2:
The preamplifier is designed with multi-functionality to serve multiple readers simultaneously. The single preamplifier unit can amplify signals from multiple read heads by using common lead connections and a shared differential pair, making one amplifier unit perform the function that previously required multiple separate amplifiers.
4Ease of operation
If independent differential amplifiers are used for each reader, then signal processing is simplified per reader, but skew and fly-height control become more difficult
Solution Approach 1:
The patent merges multiple independent differential amplifiers into a single preamplifier that handles multiple readers. The preamplifier uses a shared differential pair of transistors (first and second transistors) that can simultaneously amplify signals from multiple read heads through common lead connections, reducing the layout area while maintaining signal amplification quality.
Solution Approach 2:
The preamplifier employs feedback mechanisms through its differential pair architecture to maintain signal balance and compensate for skew and fly-height variations. The shared differential pair provides inherent feedback that helps control signal integrity across multiple readers, addressing the precision control challenges.
Data Source
AI summary
Disk drive embodiments with common lead connections in the slider, suspension, and preamplifier are described. The arm electronics IC includes a preamplifier with single-ended input from the set of signal traces that include a common signal return lead for the plurality of read transducers (readers) in the slider. Two embodiments of the preamps are described that include a single-ended design and a pseudo-single-ended design. Each embodiment supplies the required bias to each read transducer using an operational transconductance amplifier (OTA) that drives a variable current source connected to the transducer. The positive input to the OTA is a DC voltage with the AC signal from the transducer imposed on it. The negative input is a DC reference voltage. Various embodiments of the signal trace configuration on the suspension are described including a single and double layer embodiments.