Reference Current Source Temperature Compensation
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Solution Overview
Problem
Integrated circuit (IC) reference current sources using external or on-chip resistors face stability issues due to process tolerance variations and temperature fluctuations, leading to significant deviations in current output.
Innovation Solution
A current generator circuit combined with a resistance circuit comprising a current controlled resistance circuit and a voltage controlled resistance circuit, where the latter has a negative temperature dependency to counteract the positive temperature dependency of the former, allowing for temperature-independent or temperature-dependent reference current sources, with MOSFETs configured to achieve specific temperature characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an external or on-chip resistor is used to realize the reference current source, then the circuit implementation is simple, but the stability of the reference current source deteriorates due to process tolerance variations and temperature fluctuations
Solution Approach 1:
The patent changes the parameters of the resistance element from fixed (external or on-chip resistor) to dynamically controllable (current-controlled or voltage-controlled resistance circuit). By controlling the resistance value through current or voltage signals, the system can compensate for process variations and temperature effects, thereby improving reference current stability while maintaining implementation feasibility
Solution Approach 2:
The patent employs feedback mechanisms where the reference current source uses controlled resistance circuits that respond to process and temperature variations. The current-controlled or voltage-controlled resistance elements adjust their resistance values based on feedback signals, enabling automatic compensation for environmental changes and improving overall system reliability
2Device complexity
If a fixed resistance value is used, then the circuit design is simple, but the temperature stability deteriorates due to positive temperature dependency
Solution Approach 1:
The patent applies the counterweight principle by combining a resistance circuit with positive temperature dependency with another resistance circuit having negative temperature dependency. The negative temperature coefficient circuit compensates for the positive temperature drift, creating a temperature-independent reference current source. This approach maintains relatively simple circuit design while achieving excellent temperature stability
Solution Approach 2:
The patent uses composite resistance circuits combining different types of controlled resistance elements (current-controlled and voltage-controlled) with opposite temperature dependencies. This composite structure integrates multiple functional characteristics into a single system, achieving temperature independence without significantly increasing overall circuit complexity
Data Source
AI summary
Systems, methods, and apparatus for generating a reference current. A reference current source can include a current generator circuit; a first resistance circuit that has a positive temperature dependence; and a second resistance circuit that has a negative temperature dependence. The first resistance circuit and the second resistance circuit can be connected in parallel to the current generator circuit.