Transformer-Coupled VCO Filter for Millimeter-Wave Phase Noise
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Solution Overview
Problem
Voltage controlled oscillators (VCOs) face challenges in millimeter wave applications due to phase noise, which introduces second and third-order harmonic spectral components, compromising output quality and requiring effective noise suppression.
Innovation Solution
The implementation of a transformer-coupled bandpass filter (BPF) with coupled capacitors and transformers, which reduces phase noise by filtering out higher harmonics and providing a transmission zero at twice the lower cutoff frequency, thereby enhancing the frequency response and reducing noise levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a VCO is used for millimeter wave applications, then the output frequency can be varied over a range, but phase noise introduces second and third-order harmonic spectral components that compromise output quality
Solution Approach 1:
The patent extracts and removes the harmful phase noise and harmonic spectral components from the VCO output signal by introducing a bandpass filter that selectively passes only the fundamental frequency while attenuating the second and third-order harmonic components generated by the VCO
Solution Approach 2:
The patent introduces a bandpass filter as an intermediary component between the VCO and the output to mediate the signal quality. This filter acts as a mediator that allows the fundamental frequency to pass through while blocking the harmful harmonic spectral components, thereby improving output quality without affecting the frequency tuning capability
2Object-generated harmful factors
If a bandpass filter is added to suppress phase noise, then output quality improves, but device complexity increases
Solution Approach 1:
The patent designs the bandpass filter to serve multiple functions simultaneously: it suppresses phase noise, attenuates second and third-order harmonic components, and maintains the fundamental frequency signal. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving comprehensive signal conditioning
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 achieves significant phase noise reduction, with improvements of up to 14 dB or more, improving the output quality of VCOs for millimeter wave applications by effectively suppressing phase noise and maintaining signal power.
Implementation Method 1
The implementation of a transformer-coupled bandpass filter (BPF) with coupled capacitors and transformers
Data Source
AI summary
An oscillator includes a forward stage including first and second terminals and a transformer-coupled band-pass filter (BPF) coupled between the first and second terminals and including a coupling device between the first and second terminals, and a transformer including first and second windings in a metal layer of an IC. The first winding includes a first conductive structure coupled to the first terminal and a second conductive structure coupled to a voltage node, a third conductive structure including first and second extending portions connected to the first and second conductive structures. The second winding includes a fourth conductive structure including a third extending portion coupled to the voltage node, and a fourth extending portion coupled to the second terminal. The third extending portion is between the second conductive structure and the first extending portion, and the fourth extending portion is between the first conductive structure and the second extending portion.