Low-Power Startup Circuit for CMOS Bandgap References
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Solution Overview
Problem
Conventional startup-circuits for CMOS bandgap references in battery-operated mobile devices consume static currents during normal operation, reducing battery lifetime due to continuous monitoring requirements.
Innovation Solution
A low-power startup circuit with a detector circuit, level shifter, and charger circuit that disables current flow once the reference circuit reaches its desired voltage operating range, using current path controls to shut down the startup circuit and minimize power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the startup circuit remains active to continuously monitor the BG reference output, then the monitoring reliability is improved, but the power consumption increases
Solution Approach 1:
The startup circuit transitions from a static always-on state to a dynamic state that adapts based on operational needs. The circuit is enabled during startup/normal operation when monitoring is required and disabled during low-power mode when monitoring is not needed, optimizing the trade-off between reliability and power consumption
Solution Approach 2:
The startup circuit operates periodically rather than continuously - it is activated during startup and normal operation phases to monitor the BG reference output, then deactivated during low-power mode. This periodic operation eliminates unnecessary continuous monitoring while maintaining reliability when needed
2Use of energy by moving object
If the startup circuit is disabled during low-power mode, then the power consumption is reduced, but the ability to detect faults is lost
Solution Approach 1:
The circuit implements dynamic power management where the startup circuit's operational state changes based on the device's power mode. During low-power mode, the circuit is disabled to minimize consumption, while automatically re-enabling when normal operation resumes, ensuring fault detection capability is restored when needed
Solution Approach 2:
The system automatically manages the startup circuit's power state based on operational conditions. When the device exits low-power mode, the system self-activates the startup circuit to re-initialize and monitor the BG reference, eliminating the need for manual intervention while maintaining reliability
3Ease of operation
If the startup circuit consumes static current during normal operation, then the circuit remains ready for monitoring, but the battery lifetime is reduced
Solution Approach 1:
The startup circuit operates periodically rather than continuously - remaining active during normal operation to ensure readiness and monitoring capability, then entering a disabled state during low-power mode to conserve battery energy, thus extending battery lifetime without sacrificing operational readiness when needed
Data Source
AI summary
A circuit includes a startup circuit to provide a charging signal to initiate startup of a reference circuit. The startup circuit includes a detector circuit having a detector current path control, a level shifter having a level shifter current path control, and a charger circuit having a charger current path control. Each of the detector current path control, the level shifter current path control, and the charger circuit current path control enable current flow in the startup circuit when the charger turn-on signal is in the on-state and disable the current flow in the startup circuit when the charger turn-on signal is in the off state.