Bandgap Reference Circuit With Low Headroom and Noise Control
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Solution Overview
Problem
Existing bandgap voltage reference generation circuits face challenges with high noise levels and limited headroom between the supply voltage and output voltage, which can be exacerbated by reduced resistance values.
Innovation Solution
A low supply headroom bandgap voltage reference generation circuit is designed using a combination of Darlington configurations of transistors and delta base-to-emitter voltage generation circuits, along with PTAT and CTAT voltage blocks to stabilize the output voltage across varying temperatures, minimizing noise and headroom requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the resistance value of a resistive element is decreased, then the headroom between supply voltage and output voltage is reduced, but the noise level increases
Solution Approach 1:
The patent changes the configuration of the transistor circuit from a simple differential pair to Darlington pair configurations, which alters the electrical parameters (current gain, input impedance) to achieve lower headroom operation without requiring reduced resistance values that would increase noise
Solution Approach 2:
The patent uses composite transistor configurations (Darlington pairs combining multiple transistors) to create a circuit that simultaneously achieves low headroom and low noise, effectively combining the benefits of multiple transistor stages while avoiding the drawbacks of simple resistance reduction
2Temperature
If the resistance value of a resistive element is decreased to reduce headroom, then the headroom is reduced, but the manufacturing precision becomes more difficult
Solution Approach 1:
The patent changes the circuit topology to use Darlington transistor configurations, which allows headroom reduction through transistor parameter characteristics rather than relying on precise low-value resistors, thereby avoiding manufacturing precision challenges
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a stable, low-noise bandgap reference voltage with reduced headroom, maintaining accuracy and efficiency across temperature variations while optimizing circuit size and power consumption.
Implementation Method 1
generating a difference in base-to-emitter voltage between the first Darlington configuration and the second Darlington configuration using a first delta base-to-emitter-voltage resistor to produce a proportional-to-absolute temperature current
Implementation Method 2
used for generating a temperature-stabilized bandgap reference voltage
Data Source
AI summary
A low supply headroom bandgap voltage reference generation circuit for generating a bandgap reference voltage from a supply voltage can include a first delta base-to-emitter voltage generation circuit, which can include a first Darlington configuration of a first pair of transistors arranged in a differential pair with a second Darlington configuration of a second pair of transistors. A first input to the first Darlington pair of transistors can be connected to an output voltage node of the bandgap voltage reference generation circuit and a second input to the second Darlington pair of transistors can be connected to the output voltage node of the bandgap voltage reference generation circuit via a first delta base-to-emitter-voltage resistor.