Bandgap Reference Piecewise Compensation for Temperature Drift
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Solution Overview
Problem
Bandgap reference circuits in mixed signal integrated circuits experience voltage drift due to temperature variations, particularly at low temperatures, making it challenging to provide a stable reference voltage across different temperature ranges.
Innovation Solution
A piecewise compensation circuit that includes a knee code selector, an output circuit, and a trim DAC, configured to provide a correction current and compensation current to a bandgap reference circuit, setting knee point temperatures based on temperature sense signals and codes to compensate for temperature effects on the bandgap reference voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bandgap reference circuit is used to provide a reference voltage, then the reference voltage can be generated for mixed signal integrated circuit applications, but the output voltage drifts as a function of temperature including at low temperatures
Solution Approach 1:
The temperature compensation is divided into multiple segments using different knee point temperatures (first knee point temperature and second knee point temperature) that correspond to different temperature ranges. Each segment activates specific correction currents appropriate for its temperature range, enabling piecewise compensation across the full operating temperature spectrum including low temperatures.
Solution Approach 2:
The circuit dynamically changes parameters (correction current magnitude and knee point temperature) based on the detected temperature range. By selecting different knee point temperatures and adjusting correction current levels, the system adapts the compensation characteristics to match the specific temperature conditions, thereby reducing temperature drift across varying operating conditions.
2Reliability
If temperature compensation is applied to reduce voltage drift, then reference voltage stability improves, but circuit complexity increases with additional components like knee code selector and trim DAC
Solution Approach 1:
The compensation circuit employs dynamic selection of knee point temperatures through the knee code selector, allowing the circuit to adapt its compensation characteristics based on operating conditions. This dynamic approach enables a single circuit design to handle multiple temperature ranges and compensation scenarios without requiring separate fixed compensation circuits for each case.
Solution Approach 2:
The circuit uses temperature sense signals to automatically determine the appropriate knee point temperature and correction current levels without external intervention. The trim DAC and knee code selector work autonomously to select and apply the correct compensation parameters based on the detected temperature range, enabling the circuit to self-regulate and maintain accuracy across varying conditions.
Data Source
AI summary
This description relates generally to piecewise temperature compensation. In an example, a circuit includes a knee code selector that can be configured to set a knee point temperature for a correction current responsive to a respective knee point temperature code of knee point temperature codes and a respective temperature sense signal of temperature sense signals. The circuit includes an output circuit that can be configured to provide the correction current responsive to the respective temperature sense signal and temperature voltages, and a trim digital to analog converter (DAC) that can be configured to provide a piecewise compensation current responsive to the correction current and a respective trim code of trim codes.