Switched-Capacitor Oscillator Frequency Regulation Under Noise
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Solution Overview
Problem
Existing oscillator frequency regulation techniques are inadequate in maintaining stability against noise in supply voltage and temperature variations, often requiring voltage regulation that introduces additional noise and complicates linear frequency scaling.
Innovation Solution
The implementation of oscillator regulation circuitry with frequency sensing using switched capacitors and a feedback loop to generate an oscillator control signal based on a comparison with a non-oscillating reference signal, allowing for direct control of the oscillator frequency without stabilizing the supply voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage regulation is used to stabilize supply voltage to the oscillator, then frequency stability is improved, but additional noise is introduced and device complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the oscillator output is fed back through frequency sensing circuitry (including switched capacitors) that generates a control signal proportional to the oscillator frequency. This control signal is compared with a reference signal, and the difference adjusts the oscillator control signal to maintain stable frequency without requiring external voltage regulation, thereby avoiding the noise and complexity associated with voltage regulators.
2Reliability
If voltage regulation is used to stabilize supply voltage to the oscillator, then frequency stability is improved, but device complexity increases
Solution Approach 1:
The oscillator system performs its own frequency regulation through integrated frequency sensing circuitry and feedback control. The switched capacitor circuitry within the oscillator automatically generates control signals based on its own output frequency, eliminating the need for external voltage regulators or complex control circuits, thus reducing overall device complexity while maintaining frequency stability.
3Measurement precision
If frequency sensing circuitry with switched capacitors is used, then frequency control precision is improved, but sensitivity to process and temperature variations increases
Solution Approach 1:
The patent employs switched capacitor circuitry where the switching action and capacitor values are designed to create frequency-proportional control signals that are less sensitive to process and temperature variations. The feedback mechanism continuously adjusts the oscillator control signal to compensate for environmental variations, maintaining precise frequency control despite changes in process parameters or temperature.
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
This approach provides robust noise filtering, linear frequency tuning, and insensitivity to process, voltage, and temperature variations, while being friendly to low supply voltages by eliminating the need for a voltage regulator, thus ensuring precise frequency control.
Implementation Method 1
the frequency sensing circuitry comprises at least one switched capacitor
Data Source
AI summary
Oscillator regulation circuitry is provided for regulating a frequency of an output signal generated by an oscillator. Oscillator regulation circuitry has frequency sensing circuitry for sensing the frequency of the output signal and generating a first signal depending on the frequency, and control circuitry which generates the oscillator control signal based on the comparison between the first signal and a non-oscillating reference signal. The frequency sensing circuitry includes at least one switched capacitor. This approach provides improved noise reduction, less sensitivity to process, temperature and voltage variations, and a more linear scaling of the frequency with the reference signal, compared to previous techniques.