Transformer Feedback QVCO With Variable Capacitive Phase Tuning
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Solution Overview
Problem
Conventional QVCOs in 5G mobile communication systems face challenges with increased output load and decreased maximum operating frequency due to coupling networks, which induce phase offsets across ultrawide operating bands, necessitating a solution for dynamic phase error correction and improved frequency performance.
Innovation Solution
A transformer feed-back quadrature voltage controlled oscillator (QVCO) with a dynamic phase error correction circuit, utilizing variable coupling capacitors between two VCOs to correct phase errors and increase operating frequency, while reducing output load, by forming a transformer structure with induction inductors and transistors, and incorporating switching capacitor devices to shift the frequency-voltage curve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coupling network is connected to the output ends of a conventional QVCO, then quadrature phase LO signals can be generated, but the output load is increased and the maximum operating frequency is decreased
Solution Approach 1:
The coupling network is nested inside the QVCO circuit structure rather than being connected to the output ends. The capacitive coupling is implemented through internal connections between the VCO cores, effectively integrating the coupling function within the oscillator itself, which reduces the output load and allows higher operating frequencies while still generating quadrature phase LO signals
Solution Approach 2:
Capacitive coupling is used as an intermediary mechanism to transfer signals between the VCO cores. The coupling capacitors serve as mediators that enable quadrature phase signal generation without requiring direct resistive or inductive connections that would increase the output load and limit the maximum operating frequency
2Reliability
If a passive coupling network is used in a conventional QVCO, then quadrature phase signals can be generated, but phase offsets are induced at different frequencies due to ultrawide operating band
Solution Approach 1:
The coupling capacitors are made variable rather than fixed, allowing their capacitance values to be dynamically adjusted based on the operating frequency. This dynamic adjustment compensates for phase offsets that occur at different frequencies across the ultrawide operating band, maintaining accurate quadrature phase relationships from 17.2 GHz to 18.6 GHz
Solution Approach 2:
The capacitance values of the coupling capacitors are changed according to the operating frequency. By adjusting these parameters dynamically, the system compensates for frequency-dependent phase offsets and maintains consistent phase accuracy across the entire ultrawide frequency range required by 5G mobile communication standards
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 effectively corrects phase errors, increases the maximum operating frequency, and reduces phase noise, enabling lower output load and wider operating bands, meeting the requirements of 5G mobile communication systems.
Implementation Method 1
having a plurality of coupling capacitors connected between the first and second VCOs, wherein the capacitances of the coupling capacitors are varied according to a digital control signal to correct a phase error
Implementation Method 2
forming a transformer structure with induction inductors and transistors
Data Source
AI summary
A transformer feed-back quadrature voltage controlled oscillator (QVCO) includes a first VCO; a second VCO; and a dynamic phase error correction circuit, having a plurality of coupling capacitors connected between the first and second VCOs, wherein the capacitances of the coupling capacitors are varied according to a digital control signal to correct a phase error of local oscillating (LO) signals of quadrature phases output by the first and second VCOs.