Band-gap Reference Circuit With LDO Regulator
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Solution Overview
Problem
Existing band-gap reference circuits produce inaccurate output voltages at low power supply voltages, which affects their reliability and temperature independence.
Innovation Solution
A band-gap reference circuit incorporating a low drop-out (LDO) regulator that maintains a constant regulating voltage to power a reference circuit, ensuring a stable band-gap reference voltage output, utilizing a combination of operational amplifiers, transistors, and resistors to manage voltage feedback and supply voltage ranging from 1.6 V to 3.8 V.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional band-gap reference circuit is used, then the circuit can provide a temperature-independent voltage reference, but the output voltage becomes inaccurate when the power supply voltage is low
Solution Approach 1:
An LDO regulator is introduced as an intermediary component between the power supply and the band-gap reference circuit. The LDO regulator maintains a stable regulating voltage (e.g., 1.6V) regardless of fluctuations in the supply voltage (1.6V-3.8V), thereby ensuring that the band-gap reference circuit receives consistent power and produces accurate output voltage while maintaining temperature independence.
2Adaptability or versatility
If the power supply voltage varies, then the circuit can operate over a wide voltage range, but the output voltage accuracy deteriorates
Solution Approach 1:
The LDO regulator employs a feedback mechanism where a portion of the regulating voltage is fed back to the operational amplifier, which adjusts the transistor gate control voltage to maintain a constant regulating voltage despite variations in supply voltage. This feedback control ensures that the band-gap reference circuit operates accurately across the full supply voltage range of 1.6V to 3.8V.
3Device complexity
If no voltage regulation is used, then the circuit structure remains simple, but the reference voltage becomes unstable under varying power conditions
Solution Approach 1:
The LDO regulator performs preliminary voltage regulation before the signal enters the band-gap reference circuit. By pre-establishing a stable regulating voltage of 1.6V, the regulator eliminates the need for the reference circuit to tolerate voltage variations, thereby maintaining reference voltage stability while adding minimal complexity to the overall system.
Data Source
AI summary
A band-gap reference circuit including a low drop-out (LDO) regulator and a reference circuit is disclosed. The LDO regulator outputs a regulating voltage which is provided to the reference circuit, and wherein the regulating voltage is maintained constant and powers the reference circuit such that the reference circuit outputs a band-gap reference voltage. According to the reference circuitry, the LDO regulator can output a stable voltage such that the regulating voltage can be maintained constant, therefore, causing the band-gap reference voltage output from the reference circuit to be maintained constant, hence improving the reliability of the band-gap reference voltage.