Transformer LC Oscillator Tuning Without Phase Noise Drift
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Solution Overview
Problem
In transformer-based LC oscillators, the change in capacitor bank capacity for frequency tuning leads to a change in the LC tank ratio, causing deviations in input impedance and peak amplitude, resulting in increased phase noise and waveform collapse.
Innovation Solution
The implementation of a dual capacitor bank system in both the primary and secondary capacitor groups, with one bank having a maximum variable capacity and the other having a minimum variable capacity, ensures that the LC tank ratio remains constant during frequency tuning, suppressing phase noise and maintaining waveform stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a capacitor bank for frequency tuning is arranged in only one capacitor group (primary or secondary), then the oscillation frequency can be tuned, but the LC tank ratio changes causing phase noise increase and waveform collapse
Solution Approach 1:
The patent applies asymmetry by arranging capacitor banks with different maximum variable capacities in the primary and secondary capacitor groups. Specifically, the capacitor bank in one group has a maximum variable capacity that is a predetermined value or more, while the capacitor bank in the other group has a maximum variable capacity of less than the predetermined value. This asymmetric configuration allows frequency tuning while maintaining a constant LC tank ratio, thereby suppressing phase noise and preventing waveform collapse.
2Adaptability or versatility
If the capacitor bank capacity is changed for frequency tuning, then the oscillation frequency can be adjusted, but the input impedance peak position deviates and peak amplitude decreases
Solution Approach 1:
By configuring capacitor banks with asymmetric maximum variable capacities in the primary and secondary capacitor groups, the patent enables frequency adjustment while maintaining a constant LC tank ratio. This prevents the input impedance peak position from deviating and maintains peak amplitude, resolving the contradiction between frequency adjustability and impedance precision.
3Adaptability or versatility
If the LC tank ratio changes during frequency tuning, then frequency can be varied, but the third harmonic wave peak position shifts and pseudo square wave waveform collapses
Solution Approach 1:
The asymmetric capacitor bank configuration ensures that the LC tank ratio remains constant during frequency tuning. The capacitor bank in the primary capacitor group and the capacitor bank in the secondary capacitor group have different maximum variable capacities, which compensates for the ratio change that would normally occur during tuning. This maintains the waveform composition stability while allowing frequency variation.
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 configuration effectively suppresses phase noise and maintains waveform stability by preventing changes in the LC tank ratio during oscillation frequency tuning, enhancing the accuracy and reliability of the transformer-based LC oscillator.
Implementation Method 1
a transformer-based LC oscillator that includes a first LC tank having a primary-side winding of a transformer and a first capacitor connected in parallel thereto, and a second LC tank having a secondary-side winding of the transformer and a second capacitor connected in parallel thereto
Implementation Method 2
oscillation in a third harmonic wave is enabled by the action of two LC tanks on a primary side and a secondary side, and oscillation in a pseudo square wave is enabled by adding the first and third harmonic waves
Data Source
AI summary
According to the present technology, there is provided an oscillator that functions as a transformer-based LC oscillator including a first capacitor group connected in parallel to a primary-side winding of a transformer and forming a first LC tank together with the primary-side winding, and a second capacitor group connected in parallel to a secondary-side winding of the transformer and forming a second LC tank together with the secondary-side winding, the oscillator including: a first type capacitor bank that is a capacitor bank having a maximum variable capacity of a predetermined value or more, and a second type capacitor bank that is a capacitor bank having a maximum variable capacity of less than the predetermined value, as capacitor banks for oscillation frequency tuning, in which the first type capacitor banks are arranged in both of the first capacitor group and the second capacitor group.