Trim-Capable Internal Oscillator for Low-Cost Frequency Precision
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Solution Overview
Problem
Internal oscillators, particularly those using polysilicon components, suffer from imprecision due to high temperature coefficients, leading to variability in output signals, which is costly to mitigate with precise components like silicide poly-resistors or ZTCR components.
Innovation Solution
Implementing a trim-capable current source with trimmable resistors and capacitors within the oscillator, allowing for resistance and capacitance trimming to adjust charging currents and charge times, thereby compensating for process and temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polysilicon components are used in internal oscillators, then fabrication cost is reduced, but output signal precision deteriorates due to high temperature coefficients
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the oscillation frequency based on temperature measurements. A temperature sensor monitors the oscillator's temperature, and a control circuit modifies the frequency parameter in real-time to compensate for temperature-induced drift, thereby maintaining precision despite using cost-effective polysilicon components
Solution Approach 2:
The patent implements feedback control by continuously measuring the oscillator's output frequency or temperature and using this information to adjust the oscillation parameters. The control circuit receives feedback from temperature sensors or frequency detectors and automatically corrects deviations, resolving the contradiction between low-cost components and high precision requirements
2Device complexity
If polysilicon components with high temperature coefficients are used, then device complexity is reduced, but frequency stability deteriorates across temperature variations
Solution Approach 1:
The patent uses feedback control where temperature sensors monitor thermal conditions and the control circuit adjusts oscillation parameters accordingly. This closed-loop system maintains frequency stability without requiring complex temperature-compensated polysilicon components, thus keeping device complexity low while achieving high stability
Solution Approach 2:
The patent dynamically changes the oscillation frequency parameter based on temperature conditions. By adjusting this parameter in response to temperature variations, the system maintains stable performance across different thermal environments without increasing device complexity
3Measurement precision
If trim-capable components are added to compensate for variations, then output signal precision is improved, but device complexity increases
Solution Approach 1:
The patent achieves high precision by dynamically adjusting oscillation parameters based on temperature feedback. This approach provides accurate compensation for component variations without requiring multiple trim-capable components, thereby improving precision while minimizing the increase in device complexity
Data Source
AI summary
Trimming components within an oscillator comprising: a trim-capable current source, wherein the trim-capable current source comprises a trimmable resistor and a trimmable current component, a comparator comprising a first input terminal that couples to the trim-capable current source and the second input terminal that couples to a reference voltage source, a switch coupled to the first input terminal and the trim-capable current source, and a trim-capable capacitor coupled to the switch, wherein the switch is coupled between the trim-capable capacitor and the trim-capable current source.