Reference Voltage Generation Circuit Flat Temperature Characteristics
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Solution Overview
Problem
Existing reference voltage generation circuits fail to provide high precision and stability for reference output voltages across a wide temperature range, particularly from -50° C. to 150° C., due to inadequate temperature characteristics, leading to load stability issues.
Innovation Solution
A reference voltage generation circuit is designed by combining multiple reference voltage sources with different temperature characteristics, each comprising a reference voltage generation unit, amplification circuit, output transistor, and voltage regulation unit, which compares and regulates voltages to produce a maximum reference output voltage with flat temperature characteristics across a wide range by selecting the maximum voltage from individual sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single reference voltage source is used to obtain flat temperature characteristics in a predetermined range, then the temperature characteristics can be flattened in that specific range, but it is not sufficient to make temperature characteristics flat in a wide temperature range of -50°C to 150°C
Solution Approach 1:
The patent divides the wide temperature range into multiple segments by using multiple reference voltage sources, each optimized for a specific temperature range. Each reference voltage source has different temperature characteristics (e.g., first increases then decreases, second decreases then increases, third monotonically increases), and they are combined to cover the entire -50°C to 150°C range with flat temperature characteristics.
2Reliability
If multiple unit reference voltage generation circuits are formed in parallel and the one with the flattest temperature characteristics is selected, then flat temperature characteristics can be obtained even with manufacturing variation, but the remaining circuits have to be discarded causing deterioration of yield
Solution Approach 1:
Instead of selecting one circuit from multiple parallel circuits, the patent merges multiple reference voltage sources with different temperature characteristics. All sources are actively used and their outputs are combined (e.g., through addition or maximum selection) to produce the final reference voltage, thereby utilizing all manufactured circuits and improving yield while achieving flat temperature characteristics across the wide range.
3Temperature
If a reference voltage generation circuit is designed with multiple reference voltage sources having different temperature characteristics, then flat temperature characteristics in a wide temperature range can be obtained, but the device complexity increases
Solution Approach 1:
The patent designs the reference voltage sources to share common circuit structures and components where possible. Multiple reference voltage sources use similar topologies (e.g., bandgap reference structures, PTAT voltage generation), allowing them to perform multiple functions while reducing overall complexity. The sources can be activated selectively based on temperature, and their combination logic reuses existing voltage comparison and selection circuits.
Data Source
AI summary
Each of a plurality of reference voltage sources having different temperature characteristics has a reference voltage generation unit which generates a predetermined reference voltage having intrinsic temperature characteristics showing a peak voltage at different temperatures, an amplification circuit which compares the reference voltage and a feedback voltage to control an output transistor, the output transistor which generates a reference output voltage at an output terminal, and a voltage regulation unit which is able to regulate an output voltage so as to become the reference output voltage and generates the feedback voltage. A maximum reference output voltage which is the maximum of the reference output voltages is output through the output terminal.