Differential Oscillator Feedback Circuit for Common-Mode Noise Reduction
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Solution Overview
Problem
Existing oscillating signal generator circuits face challenges in reducing noise coupled into oscillation signals without compromising the sensitive gain of the oscillator, which limits the frequency tuning range.
Innovation Solution
The oscillating signal generator circuit incorporates a feedback circuit and a voltage regulator circuit that utilize a common mode sensing circuit to generate a feedback voltage, allowing the voltage regulator to regulate the supply voltage and reduce noise in the oscillating signals without decreasing the oscillator's sensitive gain by forming a closed loop with the oscillator circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the sensitive gain of the oscillator is reduced to reduce noise coupled in the oscillation signal, then the noise in the oscillation signal is reduced, but the oscillator's frequency tuning range is also reduced
Solution Approach 1:
The patent implements a feedback circuit that senses the common mode voltage of the differential oscillation signal and feeds back a compensation signal to the voltage regulator circuit. This feedback mechanism allows the system to actively cancel noise in the supply voltage without requiring reduction of the oscillator's sensitive gain, thereby maintaining both low noise performance and broad frequency tuning range
Solution Approach 2:
The patent introduces a common mode sensing circuit as an intermediary element that extracts the noise component from the differential oscillation signal. This sensing circuit acts as a mediator between the oscillator and the voltage regulator, enabling selective noise cancellation while preserving the differential signal's amplitude and frequency characteristics, thus avoiding the need to reduce sensitive gain
2Object-affected harmful factors
If the supply voltage source, bias current source, and chip create noises coupled in the oscillation signal, then noise is introduced into the system, but the oscillator requires these components for operation
Solution Approach 1:
The patent converts the harmful noise signals generated by the supply voltage source, bias current source, and chip into useful information by sensing their manifestations as common mode voltage variations in the oscillation signal. The feedback circuit then uses this information to generate compensation signals that actively cancel the noise, transforming the operational components' harmful side effects into opportunities for noise cancellation while maintaining their necessary functions
Solution Approach 2:
The patent extracts the noise component from the oscillation signal by utilizing the common mode sensing circuit to isolate the noise portion from the differential signal. This extraction process separates the harmful noise (which appears as common mode voltage) from the useful oscillation signal, allowing selective cancellation of noise while preserving the oscillator's normal operation and signal integrity
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 effectively reduces noise in the oscillating signals while maintaining the oscillator's sensitive gain, enabling a broader frequency tuning range without increasing the noise cancellation work bandwidth.
Implementation Method 1
a common mode sensing circuit coupled between the first output terminal and the second output terminal, and the common mode sensing circuit is configured to sense a common mode component of the first oscillating signal and the second oscillating signal
Implementation Method 2
The voltage regulator circuit is coupled to the oscillator circuit and the feedback circuit, and configured to regulate a supply voltage according to the feedback voltage and a second reference voltage
Implementation Method 3
The feedback circuit is coupled to the common mode sensing circuit and configured to generate a feedback voltage according to the sense voltage
Data Source
AI summary
An oscillating signal generator circuit includes an oscillator circuit, a feedback circuit, and a voltage regulator circuit. The oscillator circuit is configured to generate a first and second oscillating signal at a first and second output terminal according to a first reference voltage. The first and second oscillating signals are a differential pair of signals. The oscillator circuit includes a common mode sensing circuit coupled between the first and second output terminals. The common mode sensing circuit is configured to sense a common mode component of the first and second oscillating signals so as to generate a sense voltage. The feedback circuit, coupled to the common mode sensing circuit, is configured to generate a feedback voltage according to the sense voltage. The voltage regulator circuit is coupled to the oscillator circuit and the feedback circuit, and configured to regulate a supply voltage so as to generate the first reference voltage.