Current Mirror Fast Turn-On via Pre-Charged Control Node
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Solution Overview
Problem
In hard disk drive systems for mobile and portable devices, the preamplifier read circuits take too long to turn on from a low power state to a fully active state, which is critical for battery conservation and high-speed data access, as they are typically turned off during idle periods to conserve power but need to be operational within 100 ns for data reading.
Innovation Solution
A current mirror controller is introduced that controls the voltage at a control node to specific levels during different operational modes, using a capacitor to charge during idle periods and turning on the current mirrors quickly when data is read, minimizing the turn-on time by maintaining a charged state and reducing the charging time of the capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the preamplifier read circuits are turned off during idle periods to conserve power, then battery power is conserved, but the turn-on time becomes too long for high-speed data access
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitor during idle periods before the read operation actually begins. The capacitor is charged to a voltage that will enable fast turn-on of the current mirrors when the read operation starts, even though the mirrors themselves remain off during idle periods to conserve power.
Solution Approach 2:
The patent uses dynamics by switching the capacitor charging/discharging behavior based on operational mode. During idle periods, the capacitor charges through a resistive path; during read operations, the capacitor discharges quickly to enable fast mirror turn-on. This dynamic behavior allows the system to optimize between power consumption and speed based on operational state.
2Speed
If the capacitor charging time is reduced to enable fast turn-on, then data access speed improves, but the voltage control precision during mode transition may be compromised
Solution Approach 1:
The patent uses the capacitor as an intermediary energy storage element that mediates between the power supply and the current mirror bias requirements. By controlling the capacitor's charge state, the system can rapidly transition the mirror bias voltage without directly switching power supplies, thus achieving fast turn-on while maintaining voltage control precision through controlled charge/discharge paths.
Solution Approach 2:
The patent changes the voltage parameter at the control node dynamically based on operational mode. During idle periods, the voltage is maintained at a lower charged state to conserve power; during read operations, the voltage is rapidly changed to a higher state by discharging the capacitor, enabling fast mirror activation without compromising precision through controlled parameter transitions.
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 solution significantly reduces the turn-on time of the current mirrors, ensuring rapid activation of the preamplifier read circuits, thereby enhancing data access speed and conserving battery power by maintaining the capacitor charge during non-read intervals.
Implementation Method 1
A current mirror controller is introduced that controls the voltage at a control node to specific levels during different operational modes, using a capacitor to charge during idle periods and turning on the current mirrors quickly when data is read
Data Source
AI summary
A current mirror circuit providing a fast turn on time. A node within the circuit is held at a first voltage when the current mirror is off to permit the node voltage to quickly reach a necessary value when the current mirror circuit is turned on.