Current Mirror Pre-Charging for Fast Power Amplifier Enable
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Solution Overview
Problem
Current mirrors in power amplifiers with large capacitance require a long time to enable due to the need for a small current to charge a large capacitance, which affects the stability and noise performance of the amplifier.
Innovation Solution
A system that includes a controller providing a first current and an additional current to rapidly charge the capacitance associated with the current mirror based on a reference voltage, using specialized hardware and software to implement pre-charging circuitry that minimizes the turn-on time of current mirrors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large capacitance is used in the current mirror to meet stability and noise performance requirements, then the stability and noise performance are improved, but the enable time increases significantly
Solution Approach 1:
The patent applies preliminary action by introducing a pre-charge current path that charges the capacitance before the current mirror is fully enabled. The pre-charge transistor activates early to charge the capacitance through a dedicated path, preparing the circuit for faster transition when the main enable signal arrives, thus resolving the contradiction between large capacitance and fast enable time
Solution Approach 2:
The patent segments the charging process into two distinct phases: a pre-charge phase using a dedicated pre-charge transistor and current path, and a main operation phase. This segmentation allows the large capacitance to be charged efficiently in advance without interfering with the normal current mirror operation, thereby achieving both fast enable time and maintained stability/noise performance
2Ease of operation
If a relatively small current is used to charge the capacitance, then the current mirror can be enabled, but the charging process becomes slow
Solution Approach 1:
The patent applies dynamics by making the charging current variable rather than fixed. The pre-charge transistor's conductance can be adjusted to provide high charging current when needed, and the circuit automatically transitions to normal operation with appropriate current levels. This dynamic current adjustment enables fast charging without compromising the proper operation of the current mirror
Solution Approach 2:
The patent introduces a pre-charge transistor as an intermediary element that temporarily provides a high-current charging path. This intermediary component facilitates rapid capacitance charging without requiring the main current mirror transistors to operate in their non-linear charging region, thus achieving fast charging while maintaining ease of 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 pre-charging system significantly reduces the turn-on time of current mirrors from approximately 22 microseconds to 2.2 microseconds, enhancing the performance and efficiency of power amplifiers by rapidly biasing the current mirror.
Implementation Method 1
a controller (302) (602) for pre-charging a current mirror (362) (662). The pre-charging system significantly reduces the turn-on time of current mirrors from approximately 22 microseconds to 2.2 microseconds, enhancing the performance and efficiency of power amplifiers by rapidly biasing the current mirror.
Data Source
AI summary
A system for pre-charging a current mirror includes a controller configured to provide a first current and an additional current to a current mirror to rapidly charge a capacitance associated with the current mirror based on a reference voltage.