Temperature-Compensated Oscillator Circuit With Programmable Divider
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Solution Overview
Problem
Integrated oscillators on semiconductor chips face challenges in achieving high-precision frequency stabilization due to manufacturing variations, temperature fluctuations, and voltage variations, which are difficult to control with existing feedback-loop oscillators.
Innovation Solution
An oscillator circuit with a variable-frequency oscillator, programmable frequency divider, F/V converter, reference voltage source, feedback circuit, temperature sensor, and correction circuit that adjusts the frequency-dividing ratio based on temperature modulation, reducing temperature dependence and enabling precise frequency control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a feedback-loop oscillator is used to integrate an oscillator on a semiconductor chip, then the oscillator can be manufactured using typical semiconductor processes, but the oscillation frequency varies depending on manufacturing variation, temperature fluctuation, and voltage fluctuation, making it difficult to achieve high-precision frequency stabilization
Solution Approach 1:
The patent changes the reference from fixed physical components (capacitor C and resistor R) to a flexible digital parameter (frequency division ratio N). By controlling N through a counter and control logic, the system can dynamically adjust the oscillation frequency to compensate for manufacturing variations and environmental fluctuations, achieving high-precision frequency stabilization while maintaining semiconductor integrability
Solution Approach 2:
The patent implements a feedback mechanism where the oscillation frequency is continuously monitored and compared against a target frequency. The control logic adjusts the frequency division ratio N based on the frequency error, creating a closed-loop system that automatically compensates for deviations caused by manufacturing variations, temperature, and voltage fluctuations
2Measurement precision
If the capacitance C or resistance R is controlled with high precision to achieve accurate frequency control, then the frequency can be stabilized, but it becomes difficult to support intentional frequency shifting or modulation control
Solution Approach 1:
The patent transforms the frequency control mechanism from static (fixed C or R values) to dynamic (variable frequency division ratio N). The counter-based frequency divider can be programmatically adjusted to change N, enabling both precise frequency control and flexible frequency shifting/modulation capabilities through software or control logic without requiring physical component changes
3Manufacturing precision
If quartz resonators, ceramic resonators, or MEMS resonators are used to achieve high-precision clock generation, then the oscillation frequency can be stabilized, but an external oscillator is required as an additional component, leading to increased cost
Solution Approach 1:
The patent merges the oscillator function with the semiconductor chip's existing digital logic resources (counters, frequency dividers, control logic). By utilizing these integrated components to create a digitally-controlled oscillator, the system eliminates the need for external quartz, ceramic, or MEMS resonators, achieving high-precision frequency stabilization while reducing component count and cost
Data Source
AI summary
A variable-frequency oscillator generates an oscillator clock having a frequency that corresponds to a control signal. A programmable frequency divider divides the oscillator clock, so as to generate a divided clock. A F/V converter circuit includes a capacitor and a switch that switches at a frequency that corresponds to the divided clock, and generates a detection voltage that corresponds to a reference current. A reference voltage source outputs a reference voltage that corresponds to the electric potential that occurs at the resistor due to a reference current. A feedback circuit adjusts a control signal such that the detection voltage approaches the reference voltage. A correction circuit changes the frequency-dividing ratio of the programmable frequency divider based on a modulation signal modulated according to a correction coefficient that corresponds to the temperature.