Bandgap Reference Module for Low-Noise Fast-Startup Regulators
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Solution Overview
Problem
Portable electronic devices require a linear regulator that consumes low power, has low noise, and achieves fast start-up time to extend battery life and ensure proper functionality, especially in IoT devices where power consumption and response speed are critical.
Innovation Solution
A bandgap module with a lowpass filter and start-up circuits that includes a bandgap circuit, current mirror, and operational amplifier to generate a stable reference voltage, and an error amplifier to regulate the supply voltage, while minimizing quiescent current and noise, and accelerating start-up through a two-phase start-up procedure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a linear regulator is used to provide stable regulated voltage, then voltage stability is improved, but power consumption increases
Solution Approach 1:
The linear regulator is divided into multiple functional blocks: bandgap reference circuit, error amplifier, pass transistor, and lowpass filter. Each block performs a specific function, allowing optimization of power consumption while maintaining voltage stability through coordinated operation of these segmented components.
Solution Approach 2:
The patent optimizes power consumption by dynamically adjusting operating parameters such as bias currents in different circuits. The error amplifier and bandgap reference use minimized bias currents, while the pass transistor operates in its linear region with optimized gate voltage to reduce quiescent power consumption while maintaining regulation accuracy.
2Use of energy by moving object
If power consumption is reduced, then battery life is extended, but start-up time increases
Solution Approach 1:
The bandgap reference circuit is designed to generate the reference voltage quickly during start-up using optimized biasing schemes. The error amplifier is pre-biased to be ready for immediate operation, reducing the time required for the regulator to reach steady-state operation while maintaining low power consumption in the normal operating state.
Solution Approach 2:
The patent employs dynamic biasing where the operating currents of various circuits are adjusted based on the operational state. During start-up, higher currents are used to quickly establish voltages, then automatically reduced to low quiescent currents once regulation is achieved, thus achieving both fast start-up and low power consumption.
3Use of energy by moving object
If the bandgap circuit uses minimal current, then power consumption is reduced, but noise increases
Solution Approach 1:
A lowpass filter is introduced as an intermediary component between the bandgap reference circuit and the rest of the regulator. This filter effectively attenuates high-frequency noise generated by the minimal-current bandgap circuit while passing the DC reference voltage, thus resolving the contradiction between low power consumption and noise reduction.
Solution Approach 2:
The patent carefully selects and optimizes the parameters of the lowpass filter, specifically the resistance and capacitance values, to achieve the desired noise filtering while minimizing the impact on the reference voltage accuracy and maintaining low power consumption in the filtering circuit itself.
4Speed
If the regulated voltage is stabilized quickly, then response speed is improved, but power consumption increases
Solution Approach 1:
The error amplifier uses a compensation capacitor that creates a controlled transient response during voltage changes. This allows the system to respond quickly to load variations or input voltage changes while using minimal power during steady-state operation, as the high-current state is temporary and periodic rather than continuous.
Data Source
Figure 1A~1B
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AI summary
A bandgap module and a linear regulator are provided. The linear regulator includes the bandgap module and an error amplifier. The voltage supply voltage includes a bandgap circuit, a lowpass filter, and a start-up module. The voltage supply voltage generates a bandgap voltage. The lowpass filter filters the bandgap voltage and generates a reference voltage accordingly. The start-up module includes a first start-up circuit and a second start-up circuit. The bandgap voltage is increased to a predefined value when the bandgap module operates in a first phase. The bandgap voltage maintains at the predefined value when the bandgap module operates in a second phase. The second phase is after the first phase.