Bandgap Reference Circuit Dynamic Resistance Compensation
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Solution Overview
Problem
Existing bandgap reference power supply circuits face precision issues due to resistor variations in the fabrication process, leading to deviations in temperature characteristics and reduced performance, especially in high-frequency analog circuits, where power supply rejection ratio (PSRR) is compromised.
Innovation Solution
An adjustable resistance network with NMOS transistors and a bandgap reference power supply circuit that adjusts resistance values dynamically using control signals to compensate for process deviations, ensuring precise temperature characteristics and improved PSRR performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If multiple resistors are incorporated in the bandgap reference power supply circuit to achieve temperature compensation, then the temperature drift characteristic is improved, but the manufacturing precision deteriorates due to resistor variation in fabrication process
Solution Approach 1:
The patent extracts the temperature compensation function from the traditional multi-resistor bandgap circuit and implements it through a PTAT current source that generates a current proportional to absolute temperature. This current is used to control a switch that selectively connects compensation capacitors, thereby achieving temperature drift compensation without relying on multiple resistors with tight tolerance requirements.
Solution Approach 2:
The patent changes the operating parameter from resistor-based voltage division to current-based temperature compensation. By using a PTAT current source and dynamically switching capacitor connections based on temperature conditions, the system achieves temperature stability without being constrained by resistor fabrication variations.
2Measurement precision
If second-order curvature compensation is implemented to improve VREF precision, then the temperature characteristic precision is improved, but the device complexity increases due to additional bandgap reference voltage sources and components
Solution Approach 1:
The patent merges the temperature compensation function and curvature compensation function into a single integrated circuit structure. The PTAT current source serves dual purposes: it enables temperature drift compensation through capacitor switching and simultaneously provides curvature compensation. This consolidation achieves high VREF precision without the complexity of multiple separate bandgap reference voltage sources.
Solution Approach 2:
The patent implements a multi-functional circuit where the PTAT current source and capacitor switching network simultaneously perform both temperature compensation and curvature compensation. This universal approach allows the circuit to achieve second-order temperature characteristic precision while maintaining relatively simple structure compared to traditional methods requiring separate compensation circuits.
3Device complexity
If traditional bandgap reference circuit is used, then the circuit structure is simple, but the PSRR performance deteriorates in high frequency section
Solution Approach 1:
The patent introduces dynamic capacitor switching based on temperature conditions to optimize PSRR performance. The compensation capacitors are selectively connected or disconnected according to the PTAT current magnitude, which corresponds to temperature. This dynamic adjustment allows the circuit to maintain simple structure at low frequencies while achieving superior PSRR performance in the high-frequency section through optimized capacitance values.
Solution Approach 2:
The patent pre-calculates and pre-configures optimal capacitance values for the compensation capacitors to achieve desired PSRR characteristics. By carefully selecting capacitor values before implementation and using them in the temperature-dependent switching network, the circuit is pre-prepared to deliver high PSRR performance in the high-frequency section without requiring complex real-time adjustments.
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 effectively stabilizes the reference voltage and enhances PSRR performance across various temperature conditions, particularly in high-frequency analog circuits, by dynamically adjusting resistances to counteract fabrication process variations.
Implementation Method 1
a bandgap reference power supply circuit connected the first resistor end with the second resistor end, for generating a positive proportional to absolute temperature current flowing through the first resistor end and the second resistor end
Data Source
AI summary
A reference power supply circuit includes an adjustable resistance network and a bandgap reference power supply circuit, in which the adjustable resistance network includes a first resistor end and a second resistor end, the resistance between the first resistor end and the second resistor end varies with a process deviation; the bandgap reference power supply circuit connects the first resistor end with the second resistor end, for generating a positive proportional to absolute temperature current flowing through the first resistor end and the second resistor end and for outputting a reference voltage related to the positive proportional to absolute temperature current. The reference power supply circuit has the advantageous of high precision and good temperature drift characteristic.