Differential RC Oscillator Circuit for Low-Jitter Clock Stability
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Solution Overview
Problem
Conventional RC oscillators suffer from process deviations and noise interference, leading to significant frequency jitter and clock signal deviation due to internal noise.
Innovation Solution
An integrated circuit with a voltage-current conversion circuit, differential amplifiers, low-pass filters, and voltage-controlled oscillators is employed to amplify voltage differences, filter high-frequency noise, and modulate clock signals, thereby reducing jitter and improving frequency adjustment precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional RC oscillator structure is used, then simple structure and small area are achieved, but frequency jitter and clock signal deviation are large due to process deviation and noise interference
Solution Approach 1:
The oscillator is divided into multiple functional modules: voltage-current conversion circuit, first amplification circuit, second amplification circuit, low-pass filter, and voltage-controlled oscillation circuit. Each module performs a specific function to collectively improve frequency stability while maintaining reasonable complexity.
Solution Approach 2:
The patent implements a feedback mechanism where the output signal is fed back through the amplification circuits and voltage-current conversion circuit to continuously adjust and stabilize the oscillation frequency, reducing the impact of process deviations and noise.
2Measurement precision
If voltage-current conversion circuit is used for amplification, then frequency adjustment precision is improved, but internal noise and jitter are increased
Solution Approach 1:
The noise generated by the voltage-current conversion circuit is extracted and identified as a separate harmful factor. The differential amplification circuit is specifically designed to reject this noise while preserving the useful frequency adjustment signal, separating the signal from the noise.
Solution Approach 2:
The patent converts the noise-generating voltage-current conversion circuit into a beneficial component by using differential amplification to cancel out the noise. The same circuit that generates noise also provides the necessary frequency adjustment capability, and the differential structure transforms the harmful noise into a cancelable common-mode signal.
3Object-generated harmful factors
If differential amplification circuit is used to amplify voltage difference, then noise cancellation is achieved, but device complexity increases
Solution Approach 1:
The voltage-current conversion circuit and the differential amplification circuit are merged into a tightly coupled structure where the conversion circuit serves as the input stage of the differential amplifier. This integration reduces the number of separate components and simplifies the overall circuit while maintaining noise cancellation capability.
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
The integrated circuit effectively reduces internal noise and jitter in RC oscillators by canceling noise currents and filtering high-frequency components, stabilizing the clock signal frequency.
Implementation Method 1
a voltage-current conversion circuit, respectively input with a first voltage V REF and a second voltage V PERIOD, wherein the voltage-current conversion circuit is configured to convert the first voltage V REF input by the first input terminal or the second voltage V PERIOD input by the second input terminal into a current
Implementation Method 2
high-frequency noise in the voltage output by the second amplifier may be filtered out by the low-pass filter
Data Source
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AI summary
Embodiments of this application disclose an RC oscillator. The RC oscillator may amplify a difference between a first voltage and a second voltage by using a first amplifier and a second amplifier. The first amplifier may include a first amplification circuit and a second amplification circuit. The first amplification circuit and the second amplification circuit may share a same voltage-current conversion circuit. The RC oscillator disclosed in the embodiments of this application can not only avoid noise introduced by the first amplifier, but also reduce internal noise of the RC oscillator. This reduces a jitter of a clock signal.