Current Mirror Start-Up Using Automatic Capacitance Discharge
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Solution Overview
Problem
Current mirror power supplies often experience start-up delays due to capacitance created by the combination of circuits, which slows down the power-up process.
Innovation Solution
A power circuit with a fast power-up scheme is implemented, utilizing a first and second current mirror circuit with automatic discharge functionality to quickly start up the current through the third and fourth current paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If current mirror circuits are used to supply power to multiple circuits, then power distribution capability is improved, but start-up delay increases due to capacitance
Solution Approach 1:
The patent extracts the harmful capacitance effect from the current mirror circuit by introducing a discharge path that removes stored charge from the capacitance. The discharge transistor and discharge resistor are added to create a dedicated charge removal mechanism that operates independently from the normal current mirror function, thereby eliminating the start-up delay caused by capacitance while preserving the power distribution capability.
Solution Approach 2:
The patent implements preliminary action by pre-configuring a discharge path that automatically activates when the current mirror circuit is enabled. The discharge transistor is biased to turn on before or during the power-up sequence, proactively removing charge from the capacitance before it can cause start-up delays, thus preparing the circuit for immediate operation.
2Productivity
If circuits are combined to create current mirror functionality, then power supply efficiency is improved, but capacitance increases slowing down power-up
Solution Approach 1:
The patent introduces a discharge transistor as an intermediary element that mediates between the capacitance and the power supply. This intermediary provides a controlled path for charge discharge, allowing the capacitance to be managed without removing it entirely. The discharge transistor acts as a bridge that enables both the power supply efficiency benefits of circuit combination and the fast power-up performance by controlling charge flow.
Solution Approach 2:
The patent changes the electrical parameters of the circuit by introducing a discharge path that dynamically alters the charge state of the capacitance. The discharge resistor value and transistor sizing are carefully selected to optimize the discharge rate, changing the time constant of the circuit to achieve fast power-up while maintaining power supply efficiency during normal operation.
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
The automatic discharge mechanism enables rapid discharge of capacitance, significantly reducing start-up delays and allowing for quicker power delivery to connected circuits.
Implementation Method 1
the combination of circuits can create a capacitance that serves to slow down start-up power supplied by the current mirror. By automatically discharging the charge related with this capacitance, the start-up delay can be reduced.
Data Source
AI summary
An automatic charge/discharge circuit is presented that allows a current mirror circuit with a high capacitance to quickly and automatically charge or discharge the capacitance in order to allow for a fast start-up power supply. The charge/discharge circuit automatically stops charging or discharging as the voltage on the capacitance approached a desired steady state.