Folded Cascode Bandgap Reference Circuit Temperature Stability
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Solution Overview
Problem
Bandgap reference circuits face challenges in maintaining stability over low voltage, low power, and extended temperature ranges, as existing solutions struggle to provide a consistent reference voltage due to variations in manufacturing processes, supply voltage, and temperature.
Innovation Solution
A folded cascode bandgap reference generator circuit with an equalizer circuit using resistors to match VCE values of transistors Q1 and Q2, ensuring they operate in saturation mode and maintaining stability across temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional bandgap reference circuit is used, then a stable reference voltage can be generated, but the circuit fails to maintain stability over extended temperature ranges and low voltage conditions
Solution Approach 1:
The patent changes the operating parameters of the transistors by introducing an equalizer circuit that adjusts VCE values to maintain saturation mode operation across extended temperature ranges. This parameter adjustment allows the bandgap reference circuit to maintain stability from -40°C to over 160°C, resolving the temperature stability issue while preserving reference voltage accuracy.
2Reliability
If transistors operate in saturation mode with matched VCE values, then extended temperature stability is achieved, but additional circuit components are required
Solution Approach 1:
The patent introduces an equalizer circuit as an intermediary component that mediates between the existing bandgap core circuit and the cascode amplifier. This equalizer circuit specifically matches the VCE values of transistors Q1 and Q2, enabling saturation mode operation without requiring complete redesign of the entire circuit. The added complexity is localized and targeted, achieving temperature stability with minimal additional components.
3Use of energy by stationary object
If the circuit is designed for low voltage operation, then power consumption is reduced, but maintaining reference voltage stability becomes more difficult
Solution Approach 1:
The patent changes the voltage operating parameters by implementing an equalizer circuit that maintains proper voltage distribution across the transistor stages. This allows the circuit to operate in saturation mode at low supply voltages (down to 1.8V), simultaneously achieving low power consumption and maintaining reference voltage stability through the equalized VCE values that ensure proper transistor operation.
Data Source
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AI summary
A reference circuit includes a bandgap core circuit and a cascode amplifier. The bandgap core circuit includes a first bipolar junction transistor (BJT), a second BJT having a control electrode coupled to a control electrode of the first BJT, a first resistor coupled to the first BJT and the second BJT, and a second resistor coupled to the second BJT. The cascode amplifier circuit includes a first branch coupled to the first BJT and a second branch coupled to the second resistor.