Frequency-Locked Loop Correction Using Switched Capacitors and Resistor Drift
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing frequency-locked loops (FLLs) face challenges in correcting oscillation frequency due to temperature variations without increasing circuit complexity or area, as existing methods require additional circuits like phase-locked loops (PLLs) to detect frequency drifting.
Innovation Solution
A frequency-locked loop (FLL) comprising a switched capacitor circuit, two resistor sets, a determination circuit, and a control circuit that monitors resistance drifting between the resistors to correct the oscillation frequency by adjusting the resistances, thereby maintaining frequency stability across temperature variations without significant circuit area increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional phase-locked loops (PLLs) are used to detect frequency drifting due to temperature variation, then frequency correction capability is improved, but circuit area and complexity are greatly increased
Solution Approach 1:
The patent combines the frequency detection function with the existing FLL circuit by using the output signal of the ring oscillator itself for frequency detection, rather than adding separate PLL circuits. The switched capacitor circuit and determination circuit work together with the existing FLL components to achieve temperature compensation without duplicating the entire PLL architecture.
Solution Approach 2:
The determination circuit is designed to perform multiple functions: it detects frequency drifting caused by temperature variation, determines the direction and magnitude of correction needed, and controls the switched capacitor circuit to implement compensation. This multi-functional approach eliminates the need for separate dedicated detection and control circuits.
2Reliability
If additional phase-locked loops (PLLs) are used to detect frequency drifting, then frequency correction capability is improved, but overall design complexity is increased
Solution Approach 1:
The patent integrates the temperature compensation function into the existing FLL design by combining the switched capacitor circuit with the determination circuit and control logic. This unified approach allows frequency detection, determination, and correction to be achieved through coordinated operation of integrated components rather than separate modular blocks.
Solution Approach 2:
The FLL circuit uses its own output signal to detect frequency variations and trigger correction mechanisms. The determination circuit monitors the output frequency and automatically controls the switched capacitor circuit to compensate for temperature effects, creating a self-regulating system that does not require external control.
3Manufacturing precision
If loading capacitors are adjusted to trim frequency, then process corner variation can be corrected, but temperature variation still causes frequency drifting
Solution Approach 1:
The patent implements dynamic frequency compensation by using switched capacitor circuits that can change their capacitance values in real-time based on temperature conditions. Unlike fixed loading capacitors used for manufacturing trimming, the switched capacitors are controlled by the determination circuit to dynamically adjust and maintain frequency accuracy across varying temperatures.
Solution Approach 2:
The invention changes the operating parameters of the FLL by switching between different capacitor configurations in the switched capacitor circuit. This allows the effective capacitance to be varied dynamically in response to temperature changes, thereby maintaining stable oscillation frequency across different thermal conditions.
Data Source
AI summary
A frequency-locked loop (FLL) and a method for correcting an oscillation frequency of an output signal of the FLL are provided. The FLL includes a switched capacitor circuit, a first resistor set, a second resistor set, a determination circuit and a control circuit. The switched capacitor circuit includes a capacitor, and connection of the capacitor is switched according to the oscillation frequency. The first resistor set is configured to provide a first resistance, and the second resistor set is configured to provide a second resistance. The determination circuit is configured to generate a determination result according to the first resistance and the second resistance. The control circuit is configured to generate a control signal for correcting the first resistance and the second resistance according to the determination result, where the oscillation frequency is determined based on the capacitor and at least one of the first resistance and the second resistance.