Sample-and-Hold Reference Voltage Circuit for Low-Power LDO Refresh
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Low-power applications, such as battery-powered remote sensors, require stable reference voltages with minimal headroom to conserve battery life, but existing bandgap reference circuits are not suited for low voltage applications due to high power consumption and noise susceptibility.
Innovation Solution
A reference generator circuit that combines a bandgap reference circuit with a Low Drop Out (LDO) regulator and a sample-and-hold circuit, where the voltage regulator is disabled during the hold time to conserve power, allowing the sample-and-hold circuit to lock and output a stable reference voltage, and is refreshed periodically to maintain efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a bandgap reference circuit is used to generate stable reference voltage, then the reference voltage stability is improved, but the power consumption increases and headroom requirement increases
Solution Approach 1:
The voltage regulator is enabled only during the sample phase of the sample-and-hold circuit and disabled during the hold phase. This periodic operation allows the regulator to refresh the reference voltage periodically while consuming minimal power during the hold period, resolving the contradiction between maintaining stable reference voltage and reducing power consumption
Solution Approach 2:
The sample-and-hold circuit captures and stores the reference voltage in advance during the sample phase before the regulator is disabled. This preliminary action ensures that a stable reference voltage is already available when the regulator is turned off, maintaining voltage stability while enabling power savings
2Use of energy by moving object
If a voltage regulator operates with low headroom to conserve power, then power consumption is reduced, but the ability to maintain stable output voltage under varying conditions deteriorates
Solution Approach 1:
The sample-and-hold circuit acts as an intermediary that decouples the voltage regulator from the load during the hold phase. It stores the regulated voltage and provides it to the load independently, allowing the regulator to operate at low headroom or be disabled while maintaining stable output voltage through the held value
3Stability of the object's composition
If the voltage regulator is continuously enabled to maintain stable reference voltage, then the reference voltage stability is improved, but the battery life deteriorates
Solution Approach 1:
The voltage regulator operates in periodic cycles, being enabled during sample phases and disabled during hold phases. This periodic operation maintains reference voltage stability through periodic refreshing while significantly extending battery life by minimizing the regulator's active time and power consumption
Data Source
AI summary
A reference generator provides a reference output voltage that is continuously available while providing certain efficiencies of a duty-cycled voltage regulator. The reference output voltage is generated by a sample-and-hold circuit that is coupled to a voltage regulator. On command, the sample-and-hold circuit samples a low dropout voltage regulator that may be referenced by a bandgap circuit. During hold periods of the sample-and-hold circuit, the voltage regulator, in particular the bandgap circuit, may be disabled in order to conserve power. A sample cycle by the sample-and-hold circuit may be triggered by a signal received from a configurable finite state machine. The reference generator is effectively duty cycled in a manner that conserves available battery power, while still providing a constant reference output that is always available. The reference generator is especially suited for low-power, battery operated applications.