Sub-Volt Band Gap Reference Circuit Low-Noise Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing band gap reference voltage circuits are noisy and require high supply voltages, limiting their operational efficiency and noise reduction capabilities.
Innovation Solution
A band gap circuit design that sums temperature-compensated currents with flat-over-temperature currents and uses an operational amplifier to provide a super PTAT current, reducing noise and allowing for a lower supply voltage while maintaining a stable reference voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the current is increased to reduce noise in integrated band gap circuits, then the noise level decreases, but the power consumption and circuit area increase
Solution Approach 1:
The patent changes the operating parameters by using a current source that varies with temperature (PTAT current) instead of a constant current, and by operating the diode at a specific current density that optimizes the noise performance. This allows achieving low noise without proportionally increasing power consumption across all temperature ranges.
Solution Approach 2:
The patent employs dynamic current adjustment through temperature-dependent current sources. The current through the diode is not fixed but varies with temperature to maintain optimal noise characteristics, making the system adaptive rather than static.
2Use of energy by moving object
If the supply voltage is reduced to enable low-voltage operation, then the circuit can operate at lower voltages, but the noise performance deteriorates
Solution Approach 1:
The patent changes key parameters including the diode current density (operating at approximately 10^-4 A/cm²), the temperature coefficient of the current source, and the diode area. These parameter changes enable the circuit to achieve low noise performance at reduced supply voltages by optimizing the voltage-to-noise ratio.
Solution Approach 2:
The circuit uses temperature-dependent current sources that dynamically adjust the operating point of the diode based on temperature, allowing the circuit to maintain optimal noise performance across varying supply voltages and temperature conditions.
3Stability of the object's composition
If temperature compensation current is increased to improve voltage stability, then the reference voltage becomes more stable, but the noise from the current source increases
Solution Approach 1:
The patent optimizes the temperature coefficient of the current source to match the diode's temperature characteristics. By carefully selecting the current density and diode parameters, the circuit achieves effective temperature compensation with minimal current, reducing the noise contribution from the current source while maintaining voltage stability.
Solution Approach 2:
The patent uses multiple diodes with matched characteristics to create redundant temperature compensation paths. The current sources are designed to replicate the temperature behavior of the diodes, providing compensation without requiring excessive current that would increase noise.
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 design achieves an ultra low-noise band gap voltage reference with reduced noise levels and lower resistance requirements, enabling operation at sub-voltages and minimizing temperature compensation current, thus enhancing the circuit's noise performance and efficiency.
Implementation Method 1
detecting a first voltage drop across a first diode reference and a second voltage drop across a second voltage reference including a second diode
Implementation Method 2
supplying temperature compensation current to the first diode reference and second voltage references in response to the detected first voltage drop and second voltage drop
Implementation Method 3
A band gap circuit generates a current that varies with the absolute value of the ambient temperature
Implementation Method 4
bandgap voltage reference is a temperature independent voltage reference circuit widely used in integrated circuits, usually with an output voltage close to the theoretical 1.22 eV bandgap of silicon at 0 K
Data Source
AI summary
A method and device are disclosed for providing an ultra low-noise hand gap voltage reference. The method detects a first voltage drop across a first diode reference, and a second voltage drop across a second voltage reference that includes a second diode. The first and second voltage drops are compared. Temperature compensation currents are supplied to the first diode reference and second voltage references in addition to constant currents, where the constant currents have the same value across a first temperature range. As a result of the constant current, a minimal amount of temperature compensation current is required. Alternatively stated, temperature compensation current is provided having a rate of change greater than PTAT. In response to comparing the first voltage drop to the second voltage drop, a true sub-volt hand gap voltage is supplied across a third voltage reference including a diode, that is constant across the first temperature range.