VCO Harmonic Trap Inductor Layout for Electromagnetic Noise Rejection
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Solution Overview
Problem
Voltage controlled oscillators (VCOs) face challenges in rejecting external electromagnetic noise and preventing noise from escaping, which can adversely affect their operation and that of nearby circuits.
Innovation Solution
A VCO design featuring a first inductor arranged in a figure eight configuration with opposing current flows in its loops, and a second inductor surrounding the first inductor with opposite current direction, effectively canceling out electromagnetic noise by creating a harmonic trap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional VCO design is used, then the circuit is simple, but electromagnetic noise is not effectively rejected and can adversely affect operation
Solution Approach 1:
The first inductor is segmented into two separate loops (first loop and second loop) that are coupled together. Each loop carries current in opposite directions, creating opposing magnetic fields that cancel external electromagnetic noise. This segmentation allows the inductor to reject noise while maintaining a compact integrated structure suitable for VCO applications.
Solution Approach 2:
The patent employs counterbalancing magnetic fields generated by the two loops of the first inductor and the second inductor. Current flows in opposite directions through these loops, creating magnetic fields that act as counterweights to external electromagnetic interference, effectively canceling it out and protecting the VCO operation.
2Object-affected harmful factors
If noise rejection structures are added to the VCO, then electromagnetic noise is canceled, but the circuit area increases
Solution Approach 1:
The noise rejection functionality is merged into the existing inductor structure of the VCO. The first inductor with its two loops and the second inductor are integrated as part of the VCO's core circuitry rather than being separate added components. This merging achieves noise cancellation while minimizing additional area consumption by utilizing shared magnetic paths and coupled loop structures.
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 efficiently cancels undesired electromagnetic noise, reduces low-frequency noise, and acts as a choke to suppress higher frequency noise, improving the VCO's performance and area efficiency in electronic circuits.
Implementation Method 1
the first inductor is arranged such that current flow through first loop is in the opposite direction of current flow in the second loop... undesired coupling induced into the second conductor may be canceled based on current flow through the two inductors
Implementation Method 2
a second inductor that implements a third loop surrounding the first inductor... the current flow through one of the loops of the first inductor flows in the opposite direction of the second inductor. As a result, undesired coupling induced into the second conductor may be canceled
Data Source
AI summary
A voltage controlled oscillator (VCO) having a harmonic trap is disclosed. A VCO includes first and second transistors cross-coupled with one another. The VCO further includes a first inductor having first and second loops coupled to one another, wherein the first inductor is arranged such that current flow through first loop is in the opposite direction of current flow in the second loop. The VCO further includes a second inductor that implements a third loop surrounding the first inductor.