Transformer-Coupled Dual-Core VCO With Injection-Locked Noise Reduction
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Solution Overview
Problem
High-frequency RF oscillators face challenges in phase noise performance due to 1/f and thermal noise, limiting the accuracy and sensitivity of radar systems and other mm-wave applications.
Innovation Solution
A dual-core voltage controlled oscillator (VCO) design where two VCO cores are coupled via a transformer, synchronizing their phase and frequency, reducing effective tank resistance and thereby minimizing phase noise through injection locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-core VCO is used to generate high-frequency signals, then the device complexity is low, but the phase noise performance deteriorates due to 1/f and thermal noise
Solution Approach 1:
The VCO is divided into two separate cores (first VCO core and second VCO core), each generating oscillating signals independently. This segmentation allows noise reduction through combination while maintaining individual core simplicity, directly addressing the phase noise performance issue without excessive complexity increase.
Solution Approach 2:
The outputs of the first and second VCO cores are combined through a summing node to produce the final output signal. This merging process integrates the signals from both cores, achieving noise reduction through signal combination while maintaining the simplicity of individual core designs.
2Reliability
If the tank resistance is reduced to minimize phase noise, then the phase noise performance improves, but the power consumption increases
Solution Approach 1:
The total current consumption is segmented and distributed across two VCO cores instead of concentrating it in one core. Each core operates at reduced current levels, achieving the necessary effective tank resistance for low phase noise while distributing power consumption across multiple elements, thereby reducing the energy burden on any single component.
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 dual-core VCO achieves a 3 dB reduction in phase noise, enhancing the ability to discern small and distant objects in radar systems by improving signal-to-noise ratio and frequency agility.
Implementation Method 1
a transformer having a first winding coupled between control nodes of the pair of transistors of the first VCO core and a second winding coupled between control nodes of the pair of transistors of the second VCO core
Data Source
AI summary
In accordance with an embodiment, a method of operating a voltage controlled oscillator (VCO) includes generating a first oscillating signal in a first VCO core and generating a second oscillating signal in a second VCO core, such that the first oscillating signal and the second oscillating signal have a same frequency and a fixed phase offset. The VCO includes the first VCO core and the second VCO core, and each VCO core includes a pair of transistors. The VCO also includes a transformer having a first winding coupled between control nodes of the pair of transistors of the first VCO core and a second winding coupled between control nodes of the pair of transistors of the second VCO core.