Oscillator Temperature Compensation with Coarse-Fine Current Adjustment
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Solution Overview
Problem
Existing temperature-compensated oscillators face challenges in achieving both reduced circuit size and high resolution in frequency adjustment due to the need for precise polynomial approximation, which increases circuit complexity and size.
Innovation Solution
A circuit device with a current generation circuit that separates temperature compensation adjustments into coarse and fine adjustments using higher and lower bits of temperature compensation data, allowing for a compact coarse adjustment circuit and a high-resolution fine adjustment circuit, thereby reducing overall circuit size while maintaining high adjustment precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resolution in parameter adjustment is increased to achieve higher polynomial approximation accuracy, then the deviation of oscillation frequency is reduced, but the circuit scale increases making it difficult to reduce circuit size
Solution Approach 1:
The patent divides the temperature compensation data into upper bits and lower bits, separating the adjustment function into two independent circuits: a coarse adjustment circuit handling upper bits and a fine adjustment circuit handling lower bits. This segmentation allows each circuit to be optimized independently, reducing the overall circuit scale while maintaining high adjustment resolution through the combination of both circuits.
2Reliability
If higher-order polynomial approximation is used to improve temperature compensation accuracy, then oscillation frequency stability is improved, but circuit complexity increases
Solution Approach 1:
The patent segments the complex polynomial approximation function into multiple terms (first term, second term, third term, etc.), with each term processed by a separate circuit block. Each block generates a specific function current corresponding to a polynomial term, and these currents are summed to achieve the complete temperature compensation. This segmentation reduces circuit complexity by breaking down the higher-order approximation into manageable, modular components.
Solution Approach 2:
The patent merges multiple function currents from different polynomial terms into a single combined current that represents the complete temperature compensation function. By using a current summation node to combine the outputs of multiple simplified circuit blocks, the patent achieves high-order polynomial approximation accuracy without requiring a single complex circuit, thereby reducing overall circuit complexity.
Data Source
AI summary
The circuit device includes a current generation circuit and a current-voltage conversion circuit. The current generation circuit generates a temperature compensation current based on a temperature detection voltage from the temperature sensor and temperature compensation data. The current-voltage conversion circuit converts the temperature compensation current into the temperature compensation voltage. The current generation circuit performs a fine adjustment of the temperature compensation current based on lower bits of the temperature compensation data, and performs a coarse adjustment of the temperature compensation current based on higher bits of the temperature compensation data.