Low Power Reference Voltage Circuit with Periodic Sampling
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Solution Overview
Problem
Existing electronic devices face challenges in achieving low power consumption while maintaining stable reference voltage levels, especially when power supply voltage fluctuates, leading to significant power loss and inefficiency.
Innovation Solution
A system that generates a low power reference voltage using a regulation circuit, sample-and-hold storage circuit, and control circuit to cyclically couple the power supply and storage circuit, controlling the timing based on circuit characteristics to minimize voltage fluctuations and leakage, thereby reducing power consumption and maintaining a consistent reference voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a reference voltage circuit is continuously coupled to the power supply to maintain stable reference voltage, then the reference voltage stability is improved, but the power consumption increases
Solution Approach 1:
The patent implements periodic sampling of the reference voltage through a switch that periodically connects the reference voltage circuit to the storage capacitor. Instead of continuous coupling, the circuit samples the reference voltage at regular intervals determined by the RC time constant, allowing the storage capacitor to maintain the reference voltage between samples. This periodic action significantly reduces power consumption while maintaining adequate voltage stability.
Solution Approach 2:
The storage capacitor is pre-charged to the reference voltage level during the sampling phase, preparing it to maintain the reference voltage during the non-sampling period. This preliminary charging action ensures that when the switch opens, the capacitor already holds the correct voltage level, eliminating the need for continuous power supply connection.
2Loss of energy
If the power supply voltage is regulated to a low voltage to reduce power loss, then the power efficiency is improved, but the reference voltage becomes sensitive to power supply noise and fluctuations
Solution Approach 1:
The storage capacitor acts as an intermediary between the power supply and the reference voltage circuit. It decouples the reference voltage from direct power supply fluctuations by storing energy and providing a stable voltage output. The capacitor filters out noise and variations from the regulated power supply, ensuring reliable reference voltage even when the power supply voltage changes.
Solution Approach 2:
The storage capacitor provides beforehand cushioning by being pre-charged to the reference voltage level. When power supply fluctuations occur, the capacitor releases stored energy to maintain the reference voltage, cushioning against the effects of power supply noise and variations before they can affect the reference voltage circuit.
3Reliability
If the reference voltage circuit operates continuously to handle large power supply variations, then the power supply rejection ratio is improved, but the power consumption increases significantly
Solution Approach 1:
The circuit uses periodic sampling with an RC time constant designed to provide adequate power supply rejection during each sampling interval. The switch periodically connects the reference voltage circuit to the storage capacitor, allowing the circuit to achieve good PSRR during active periods while consuming minimal power during idle periods when the switch is open.
Solution Approach 2:
The circuit dynamically switches between active sampling mode and idle storage mode. During sampling, the circuit actively regulates the reference voltage with full power supply rejection capability. During idle periods, the storage capacitor maintains the voltage with minimal power consumption. This dynamic operation allows the circuit to achieve high average PSRR while maintaining low average power consumption.
Data Source
AI summary
A reference voltage that is consistent over various operational conditions and uses low power is provided. According to an example, an internal temperature-compensated voltage (e.g., vdd_int in 200) is generated from a power supply (e.g., vdd in 200), and a reference voltage (e.g., vref in 200) is generated from the internal voltage. The reference voltage is stored on a storage circuit (e.g., 430) that is coupled (charged) and refreshed under conditions, relative to circuit characteristics, that make low and ultra-low power operation possible.