Tunable Magnetic Coupling in Complementary Oscillators for Phase Noise
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Solution Overview
Problem
Designing satisfactory local oscillator circuitry for electronic devices with wireless communications capabilities is challenging due to the impact of phase noise on signal-to-noise and distortion ratio, which can degrade error vector magnitude, especially with stringent modulation schemes.
Innovation Solution
Implementing a transformer-based phase noise filter in the oscillator circuitry with a tunable magnetic coupling circuit and a programmable resistor to adjust magnetic coupling between tail coils, allowing for extended filter tuning range without sacrificing the quality factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a transformer-based phase noise filter is implemented in the oscillator circuitry, then phase noise suppression is improved, but the device complexity increases due to additional components
Solution Approach 1:
The patent embeds the phase noise filter circuitry within the existing oscillator structure by coupling the filter's tail coils to the oscillator's tail nodes. The filter is nested inside the oscillator block, sharing common nodes and integrating seamlessly with the cross-coupled transistor pair, thereby reducing overall device complexity while maintaining phase noise suppression functionality
Solution Approach 2:
The patent introduces a tunable magnetic coupling circuit as an intermediary element between the oscillator tail coils and the phase noise filter tail coils. This magnetic coupling circuit, implemented through coupled inductors with adjustable coupling coefficients, mediates the interaction between the oscillator and filter circuits, enabling independent optimization of both phase noise suppression and tuning range without direct complex interconnections
2Adaptability or versatility
If the magnetic coupling between tail coils is increased to extend filter tuning range, then the tuning range is improved, but the quality factor decreases
Solution Approach 1:
The patent implements a tunable magnetic coupling circuit where the coupling coefficient between the oscillator tail coils and filter tail coils can be dynamically adjusted. By varying the coupling coefficient k between 0 and 1, the system can adaptively optimize the balance between tuning range extension and quality factor maintenance, allowing the filter to achieve wide tuning range while preserving high Q-factor performance through optimal coupling selection
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 solution provides improved phase noise suppression, maintaining the quality factor of the filter while extending the tuning range, thereby enhancing the performance of wireless communications in electronic devices.
Implementation Method 1
a tunable magnetic coupling circuit magnetically coupled to the first tail coil. The oscillator circuitry can further include a second tail coil coupled to the second tail node and magnetically coupled to the tunable magnetic coupling circuit
Data Source
AI summary
Oscillator circuitry is provided that includes a pair of n-type transistors coupled to a first tail node, a pair of p-type transistors coupled to a second tail node, a first tail coil coupled to the first tail node, and a tunable magnetic coupling circuit magnetically coupled to the first tail coil. The oscillator can further include a load inductor, a load capacitor, a second tail coil coupled to the second tail node and magnetically coupled to the tunable magnetic coupling circuit, and a tunable capacitor having a first terminal coupled to the first tail node and having a second terminal coupled to the second tail node. The tunable magnetic coupling circuit can include a first coupling coil magnetically coupled to the first tail coil, a second coupling coil magnetically coupled to the second tail coil, and a programmable resistor coupled to the first and second coupling coils in a loop.