Parallel Complementary VCO Arrays With Shared Inductors for Low Phase Noise
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Solution Overview
Problem
Integrated voltage controlled oscillators (VCOs) face challenges in minimizing phase noise, especially at higher frequencies, which affects mixing performance, noise floor, noise transmission, and bit error rate in wireless communication systems.
Innovation Solution
The design of integrated VCO arrays with single turn inductor coils and complementary pairs connected in parallel, where adjacent segments of inductor coils are shared, increasing the quality factor and reducing phase noise, and further improvements are achieved by increasing the number of VCOs in an array, with interior VCOs benefiting from greater shared coil segments and opposing flux polarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If integrated VCOs use planar inductor coils formed from metal layers in ICs, then manufacturing integration is improved, but phase noise increases at higher frequencies
Solution Approach 1:
The patent divides a single VCO into multiple identical VCOs arranged in an array (e.g., four VCOs). Each VCO is segmented to share portions of inductor coils with adjacent VCOs, reducing the inductance value while maintaining total oscillation energy. This segmentation allows integration benefits while mitigating phase noise through distributed architecture.
Solution Approach 2:
Adjacent VCOs in the array merge by sharing common inductor coil segments. The shared segments create magnetic coupling between VCOs, combining their oscillation energies constructively. This merging increases the effective quality factor and reduces phase noise while maintaining IC integration benefits.
2Object-affected harmful factors
If multiple VCOs are connected in parallel with shared inductor segments, then phase noise is reduced, but device complexity increases
Solution Approach 1:
The inductor coil structure is segmented into shared and dedicated portions for each VCO in the array. Each VCO uses a combination of shared segments (coupled with adjacent VCOs) and dedicated segments (unique to that VCO), creating a systematic pattern that reduces phase noise while maintaining manageable complexity through repetition.
Solution Approach 2:
The shared inductor segments serve multiple functions simultaneously: they provide inductance for multiple adjacent VCOs, create magnetic coupling for phase noise reduction, and enable area efficiency through资源共享. This multi-functionality reduces the need for separate components, offsetting the increased device complexity.
3Object-affected harmful factors
If VCOs share inductor coil segments, then quality factor increases and phase noise decreases, but magnetic field interference occurs between adjacent VCOs
Solution Approach 1:
The patent converts the harmful magnetic field interference between adjacent VCOs into a beneficial coupling effect. By carefully designing the shared inductor segments, the magnetic fields from adjacent VCOs interact constructively, increasing the effective quality factor and reducing phase noise. The potential interference is transformed into useful magnetic coupling.
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 results in a significant reduction of phase noise, with each doubling of VCOs in the array reducing phase noise by 3 dB, and achieving up to 12 dB reduction in phase noise for an array of 16 VCOs, while also optimizing IC area usage and magnetic field interference cancellation.
Implementation Method 1
adjacent segments of inductor coils are shared, increasing the quality factor and reducing phase noise
Implementation Method 2
interconnects 18-20 provide suitable connections for supply lines, control signals and like. If desired, interconnects 18-20 can also provide the necessary connections to the oscillator output
Implementation Method 3
A commonly used type of harmonic VCO utilizes a resonant circuit formed by inductors and capacitors and correspondingly is known as an LC VCO
Data Source
Figure 1~2
Figure 3
AI summary
This disclosure involves systems for providing an oscillatory circuit having low phase noise featuring arrays of complementary VCO pairs connected in parallel sharing segments of single turn inductor coils.