Bandgap Reference Circuit Using Averaged Current Mirrors for Low Noise
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Solution Overview
Problem
Existing bandgap reference circuits face challenges in providing accurate voltage references over a wide range of supply voltages and temperatures, often resulting in multiple operating points and inaccuracies due to offset voltages and current mismatching, especially in automotive and portable applications where low power consumption and stability are critical.
Innovation Solution
A bandgap reference circuit design that includes a first and second current mirror circuit, an amplifier, and a start-up circuit, which generates a temperature-compensated bandgap voltage by mirroring averaged currents through diode-connected PFETs, ensuring minimal impact from transistor mismatches and reducing quiescent current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bandgap reference circuits are used to provide voltage references over wide supply voltage ranges, then voltage reference stability is improved, but quiescent current consumption increases and multiple operating points appear causing inaccuracies
Solution Approach 1:
The circuit is divided into two distinct stages: a first stage generating a first current and a second stage generating a second current. This segmentation allows independent optimization of each stage's current consumption while maintaining overall voltage reference stability across wide supply voltage ranges (2V to 6V), thereby reducing total quiescent current without sacrificing reliability.
Solution Approach 2:
The patent changes the operating parameters by using diode-connected PFETs with specific width-to-length ratios (e.g., 10:1 or 20:1) to mirror averaged currents. This parameter optimization enables the circuit to maintain accurate voltage references while consuming lower quiescent current, resolving the contradiction between stability and energy consumption.
2Adaptability or versatility
If conventional bandgap reference circuits operate over wide supply voltage ranges, then adaptability is improved, but inaccuracies increase due to offset voltages and current mismatching
Solution Approach 1:
The patent merges the first current from the first stage and the second current from the second stage through current mirror circuits using diode-connected PFETs. This combining of averaged currents from two independently optimized stages maintains voltage reference accuracy across wide supply voltage ranges (2V to 6V) by canceling out offset voltages and current mismatches that would otherwise cause inaccuracies.
Solution Approach 2:
The circuit employs feedback mechanisms where the amplifier monitors and adjusts the currents based on voltage differences detected at its input terminals. This feedback ensures that despite variations in supply voltage, the combined current produces an accurate bandgap voltage reference, maintaining measurement precision while achieving wide adaptability.
3Use of energy by moving object
If bandgap reference circuits are designed for low power consumption, then energy efficiency is improved, but noise increases and stability over wide supply ranges deteriorates
Solution Approach 1:
The circuit dynamically adapts its operation across wide supply voltage ranges (2V to 6V) by using voltage-dependent current mirror ratios. The diode-connected PFETs automatically adjust current distribution based on the supplied voltage, enabling low power consumption at higher voltages while maintaining stability and low noise at lower voltages through optimized current paths in each stage.
Data Source
AI summary
In described examples, a circuit includes a first current mirror circuit. The first current mirror circuit is coupled to a power input terminal. A first stage is coupled to the first current mirror circuit, and a second stage is coupled to the first stage and to the first current mirror circuit. An amplifier is coupled to the first and second stages. The amplifier has first and second input terminals. The first input terminal is coupled to the first stage, and the second input terminal is coupled to the second stage. A second current mirror circuit is coupled to the first stage, the second stage and the amplifier.