VCO Virtual Power Supply Feedback for Low Phase Noise
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Solution Overview
Problem
Conventional voltage-controlled oscillators (VCOs) in communication systems are vulnerable to power noise, which increases phase noise and jitter, degrading communication performance due to external electromagnetic interference and temperature changes.
Innovation Solution
A voltage-controlled oscillator is designed with a regulating unit maintaining a stable virtual power supply using a reference voltage and a power noise removal unit employing negative feedback through a closed-circuit loop formed by corresponding transistors to detect and remove power noise, ensuring low phase noise and jitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional VCO with PLL is used, then frequency stability is achieved through feedback control, but power noise from external EMI degrades phase noise and jitter performance
Solution Approach 1:
The VCO power supply network is segmented into multiple independent domains: a first power supply for the PLL circuit and a second power supply for the VCO core circuit. This segmentation isolates the VCO core from EMI noise affecting the PLL, allowing the VCO to maintain stable oscillation frequency even when external electromagnetic interference is present on the power line.
Solution Approach 2:
A dedicated power supply circuit acts as an intermediary between the main power source and the VCO core circuit. This intermediate power supply stage filters and conditions the power delivered to the VCO core, blocking EMI noise from reaching the sensitive oscillation circuit while maintaining the required voltage levels for stable operation.
2Device complexity
If single power supply is used for PLL and VCO, then circuit complexity is reduced, but EMI noise affects both circuits and degrades communication performance
Solution Approach 1:
The power supply structure is segmented into multiple independent domains: a first power supply for the PLL circuit and a second power supply for the VCO core circuit. This segmentation isolates the VCO core from EMI noise affecting the PLL, allowing the VCO to maintain stable oscillation frequency even when external electromagnetic interference is present on the power line.
3Object-affected harmful factors
If VCO is made robust against power noise through filtering, then phase noise is reduced, but response speed to frequency tuning may be affected
Solution Approach 1:
The power supply network is segmented into multiple independent domains: a first power supply for the PLL circuit and a second power supply for the VCO core circuit. This segmentation isolates the VCO core from EMI noise affecting the PLL, allowing the VCO to maintain stable oscillation frequency even when external electromagnetic interference is present on the power line.
Solution Approach 2:
The invention changes the power supply parameters (voltage level, noise characteristics) delivered to the VCO core circuit by using a dedicated second power supply. This allows optimization of the VCO operating point for low phase noise while maintaining fast tuning response through appropriate biasing conditions in the segmented power supply architecture.
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 a stable single oscillation frequency with low phase noise and jitter, enhancing communication performance by effectively filtering out power noise and maintaining frequency stability across temperature changes.
Implementation Method 1
a regulating unit configured to maintain a virtual power supply of a VCO core circuit in a stable condition with regard to a reference voltage
Implementation Method 2
a power noise removal unit including second transistors configured to correspond to respective first transistors of the regulating unit, the power noise removal unit being configured to remove power noise of the virtual power supply by using negative feedback through a closed-circuit loop formed by each of the first and second transistors
Data Source
AI summary
A voltage-controlled oscillator robust against power supply includes: a regulating unit configured to maintain a virtual power supply of a VCO core circuit in a stable condition with regard to a reference voltage; and a power supply removal unit including second transistors configured to correspond to respective first transistors of the regulating unit, the power supply removal unit being configured to remove power noise of the virtual power supply by using negative feedback through a closed-circuit loop formed by each of the first and second transistors.