Split-Rail Biasing Circuit for Any-Order Power-Up
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Solution Overview
Problem
Designing integrated electronic circuits with split-rail power supply systems poses a challenge in ensuring that gate-source voltages remain below maximum allowable levels during power-up, as conventional methods often sequence power supply rails in a way that can damage transistors and lead to inefficiencies in power consumption.
Innovation Solution
A method and apparatus that utilize intermediate voltage generators at each pad, powered by a temporary supply voltage, which selectively switch between internal and external voltages under control of a power signal, ensuring safe operation and reducing power consumption by disabling unused voltage generation circuits when external power rails are safe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional power-up sequencing is used to ensure gate-source voltage remains below maximum allowable levels, then transistor reliability is improved, but power consumption increases and power-up flexibility is reduced
Solution Approach 1:
The patent applies preliminary action by generating intermediate voltages (e.g., 1.8V) from high supply voltage (3.3V) before the external intermediate voltage rail is ready. Temporary intermediate voltage generators are activated in advance to provide safe operating voltages to circuits during power-up, preventing excessive gate-source voltages before the external power rails are fully established.
Solution Approach 2:
The patent uses intermediate voltage generators as intermediary components that convert high supply voltage (3.3V) to intermediate voltage (1.8V) to safely power circuits during power-up. These intermediate voltage generators act as mediators between the high voltage rail and voltage-sensitive circuits, allowing power-up in any sequence while protecting transistors from damage.
2Adaptability or versatility
If temporary supply voltage is distributed to all pads to allow any power-up sequence, then power-up flexibility is improved, but power consumption increases due to unused voltage generation circuits
Solution Approach 1:
The patent applies dynamics by making the temporary supply voltage distribution adaptive rather than static. Multiplexers dynamically switch between temporary and external voltage sources based on power-up status. When external voltage rails become ready, the system transitions from using temporary generators to using external voltages, automatically disabling unused circuits to minimize power consumption while maintaining flexibility.
Solution Approach 2:
The patent uses feedback through power status detection circuits that monitor when external voltage rails are ready. This feedback controls multiplexers to switch from temporary to external voltage sources and disables temporary generators when no longer needed, optimizing power consumption based on real-time power-up status.
3Reliability
If intermediate voltage generators are kept active to ensure continuous safe operation, then circuit safety is improved, but power consumption increases
Solution Approach 1:
The patent applies discarding and recovering by temporarily using intermediate voltage generators only during power-up when external rails are not ready, then discarding (disabling) them when external voltages become available. The temporary generators are recovered for use only when external power rails fail or during initial power-up, minimizing power loss while ensuring circuit safety during critical transitions.
Data Source
AI summary
A low power biasing circuit for powering up split-rail electronic circuits includes an intermediate voltage generator at each pad which is supplied by a temporary supply voltage to generate a temporary intermediate voltage only when a power signal indicates that all external voltage rails are not safe, thereby reducing power consumption.