Transformer Feedback QVCO With Dynamic Quadrature Phase Correction
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Solution Overview
Problem
Conventional transformer feed-back quadrature voltage controlled oscillators (QVCOs) face challenges in correcting dynamic phase errors and maintaining high operating frequencies due to coupling network limitations, which are critical for 5G mobile communication standards requiring accurate LO signals.
Innovation Solution
A transformer feed-back QVCO with a dynamic phase error correction circuit using variable coupling capacitors connected between two VCOs, allowing digital control to adjust capacitances and correct phase errors, while integrating a frequency tuning circuit to increase operating frequency and reduce output load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coupling network is connected to output ends of conventional QVCO, then quadrature phase 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 oscillator circuit by connecting it to the tank circuit through the transformer feedback mechanism. This internal integration allows the coupling network to function without adding external output load, thereby maintaining high operating frequency while still generating quadrature phase signals.
Solution Approach 2:
The transformer serves as an intermediary element that couples the oscillation signal to the coupling network. By using the transformer feedback mechanism, the coupling network receives signals through the transformer rather than directly from the output ends, which reduces the output load effect and preserves the maximum operating frequency.
2Reliability
If a passive coupling network is used in conventional QVCO, then quadrature phases can be obtained, but phase offsets are induced at different frequencies due to ultrawide operating band
Solution Approach 1:
The transformer feedback mechanism provides a feedback path that automatically compensates for phase offsets. The feedback signal from the coupling network is fed back to the tank circuit through the transformer, creating a self-correcting system that maintains accurate quadrature phase relationships across the ultrawide operating band without requiring external phase correction circuits.
3Speed
If frequency tuning circuit is integrated inside the transformer feed-back QVCO, then operating frequency can be increased, but the circuit complexity is increased
Solution Approach 1:
The transformer serves multiple functions: it provides the feedback mechanism for oscillation, enables the coupling network operation, and facilitates frequency tuning. By making the transformer a multi-functional component, the frequency tuning circuit can be integrated without proportionally increasing overall circuit complexity, as the transformer already performs these functions as part of its core operation.
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 the transformer feed-back QVCO to meet 5G mobile communication requirements with improved performance and wider operating bands.
Implementation Method 1
a first end of a induction inductor of the transformer to form a transformer feed-back structure
Implementation Method 2
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
Data Source
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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.