RC Oscillator With Bandgap Current Temperature Compensation
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Solution Overview
Problem
The precision of oscillation frequency in common RC oscillator circuits is limited by temperature drift and other external factors, affecting the reliability of the oscillator's output.
Innovation Solution
An oscillator design incorporating an RC oscillator and a bandgap reference source with an adjustable temperature coefficient for the reference current, which is used to compensate for the temperature effects on the oscillation frequency, thereby improving precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a common RC oscillator circuit with current steering structure is used, then the oscillation frequency is independent of power supply voltage, but the frequency precision is limited by temperature drift of CMOS devices
Solution Approach 1:
The patent introduces a bandgap reference source that generates a reference current with adjustable temperature coefficient to compensate for the temperature drift of the RC oscillator. By changing the temperature parameter of the reference current, the system compensates for frequency precision degradation caused by temperature variations in CMOS devices.
Solution Approach 2:
The patent implements a feedback mechanism where the bandgap reference source continuously provides a temperature-compensated reference current to the RC oscillator. This feedback loop adjusts the oscillator's operating parameters based on temperature conditions, maintaining frequency precision while preserving power supply independence.
2Measurement precision
If the temperature coefficient of the reference current is adjusted to compensate for temperature drift, then the oscillation frequency precision is improved, but the device complexity increases
Solution Approach 1:
The patent merges the bandgap reference source and the RC oscillator into a single integrated circuit system. By combining these two functional blocks on the same substrate and using shared power supply and grounding structures, the patent reduces overall device complexity while achieving temperature compensation for improved frequency precision.
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 enhances the oscillation frequency precision by reducing temperature-induced variations, allowing the oscillator to maintain a stable output frequency across different temperatures and power supply conditions.
Implementation Method 1
a bandgap reference source 30, wherein: the bandgap reference source 30 provides a reference current IREF for the RC oscillator 10; and a temperature coefficient of the reference current output by the bandgap reference source 30 is adjustable
Data Source
AI summary
An oscillator comprising an RC oscillator and a bandgap reference source, wherein the bandgap reference source provides a reference current for the RC oscillator, and a temperature coefficient of the reference current is adjustable. Since the oscillation frequency of the RC oscillator has less dependency on a power supply, a clock source having a relatively precise frequency thus can be obtained; and based on the RC oscillator, the bandgap reference source having a temperature compensation function is added, the reference current generated by the bandgap reference source with an adjustable temperature coefficient is used for temperature coefficient compensation to the inherent temperature coefficient of the oscillation frequency of the RC oscillator, thereby reducing the effect of the temperature on the oscillator, so that the output frequency of the oscillator does not change with the temperature as far as possible, which improves the oscillation frequency precision of the oscillator.