Reference Current Generator Circuit Temperature Compensation
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Solution Overview
Problem
Electronic circuits face challenges in maintaining accurate and stable reference signals, particularly reference currents, due to temperature changes and process variations, which can lead to frequency drift and reduced accuracy.
Innovation Solution
A reference current generator circuit is designed with a bias circuit and transistors configured to provide a reference current and a second current with proportional magnitudes, where the second pair of transistors offers a collective resistance value proportional to temperature, and a PTAT voltage source ensures the reference current remains constant across temperature variations, implemented in conjunction with an oscillator circuit to maintain stable frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reference current is generated to bias an oscillator circuit, then the oscillator circuit can operate with a stable frequency, but transients in the magnitude of the reference current can result in frequency drift of the oscillator circuit
Solution Approach 1:
The patent employs a PTAT voltage source that generates a voltage proportional to absolute temperature, and couples it with a resistor having resistance proportional to temperature. This parameter change strategy ensures that the reference current remains stable across temperature variations, preventing frequency drift in the oscillator circuit while maintaining reliable operation.
2Measurement precision
If process and environmental considerations such as temperature changes are taken into account, then the accuracy of the electronic circuit can be maintained, but the magnitude of the reference signal changes with temperature
Solution Approach 1:
The patent converts the harmful effect of temperature changes into a beneficial mechanism by using a PTAT voltage source and a temperature-proportional resistor. These components exploit temperature variations to generate compensating effects that stabilize the reference current magnitude, thereby maintaining reference signal accuracy despite temperature fluctuations.
3Reliability
If the reference current magnitude is made stable with respect to temperature, then the electronic circuit operates accurately, but the circuit complexity increases due to additional temperature compensation mechanisms
Solution Approach 1:
The patent merges the temperature compensation function into the existing reference current generation circuitry by integrating a PTAT voltage source and a temperature-proportional resistor directly into the current generation path. This consolidation achieves temperature-stable reference current without adding separate, complex compensation stages, thereby maintaining reliability while controlling circuit complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a stable reference current that is independent of temperature and process variations, ensuring accurate operation of electronic circuits by maintaining a constant reference current magnitude and frequency stability.
Implementation Method 1
a proportional to absolute temperature (PTAT) voltage source configured to generate a PTAT voltage at a node in the second current path, such that the reference current has a magnitude that is based on the magnitude of the PTAT voltage and is substantially constant with respect to temperature
Data Source
AI summary
One aspect of the present invention includes a reference current generator circuit. The circuit includes a bias circuit configured to generate a reference current along a first current path and a second current along a second current path. The reference current and the second current can be proportional. The circuit also includes a first pair of transistors connected in series and configured to conduct the reference current in the first current path. The circuit further includes a second pair of transistors connected in series and configured to conduct the second current in the second current path. The second pair of transistors can be coupled to the first pair of transistors to provide a collective resistance value of the second pair of transistors that is proportional to temperature.