MOS Stack Voltage Reference Circuit Temperature Compensation
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Solution Overview
Problem
Voltage reference circuits face challenges in maintaining a stable, temperature-independent reference voltage due to variations in temperature and power supply, particularly in devices with different MOS transistor thresholds, which complicates process manufacturing and increases power consumption.
Innovation Solution
A voltage reference circuit utilizing a metal-oxide semiconductor (MOS) stack with two or more MOS transistors of the same voltage threshold, generating voltage waveforms with opposite temperature coefficients, and a summation circuit to merge these waveforms, thereby canceling out temperature coefficients and maintaining a stable reference voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If MOS transistors with different voltage thresholds are used, then device functionality is achieved, but process variation increases and manufacturing precision deteriorates
Solution Approach 1:
The patent employs MOS transistors with matching voltage thresholds (e.g., both at 0.7V) instead of transistors with different thresholds. This homogeneity in electrical characteristics reduces process variation and improves manufacturing precision while maintaining device functionality. The matched thresholds ensure consistent operation across temperature variations and improve the stability of the voltage reference circuit.
2Reliability
If conventional voltage reference circuits are used, then reference voltage is provided, but power consumption increases
Solution Approach 1:
The patent changes the operating parameters of the MOS transistors, specifically utilizing their threshold voltage characteristics and temperature coefficients. By carefully selecting transistors with complementary temperature coefficients and adjusting their operating points, the circuit achieves temperature compensation without requiring excessive current, thereby reducing power consumption while maintaining reference voltage stability.
Solution Approach 2:
The patent converts the harmful effect of temperature variations on MOS transistor thresholds into a beneficial feature. By using transistors with opposite temperature coefficients (one whose threshold increases with temperature and another whose threshold decreases), the circuit compensates for temperature drift, turning what would be a source of error into a mechanism for temperature stabilization, thus reducing the need for high power consumption to maintain stability.
3Stability of the object's composition
If temperature compensation is implemented, then temperature independence is achieved, but circuit complexity increases
Solution Approach 1:
The patent merges the temperature compensation function directly into the voltage reference generation circuit by using a stacked configuration of MOS transistors. Instead of adding a separate compensation circuit, the temperature compensation is achieved by combining transistors with complementary temperature characteristics in series, allowing the reference voltage to be temperature-independent while avoiding additional circuit complexity.
Data Source
AI summary
A voltage reference circuit is provided. In some embodiments, the voltage reference circuit includes a MOS stack that includes two or more MOS transistors having a substantially same voltage threshold. The voltage reference circuit is configured to generate, via the MOS stack, a first voltage waveform having a first temperature co-efficient and a second voltage waveform having a second temperature co-efficient. In some embodiments, the first temperature co-efficient has a polarity that is opposite a polarity of the second temperature co-efficient. In some embodiments, the first voltage waveform and the second voltage waveform are used to generate a reference voltage waveform, where the reference voltage waveform is substantially temperature independent due to the opposite polarities of the first temperature co-efficient and the second temperature co-efficient.