Transformer Resonator Circuit With Split-Mode Harmonic Trapping
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Solution Overview
Problem
Existing radio frequency (RF) resonator circuits face challenges in maintaining frequency stability and phase noise performance due to the Groszkowski effect, which is exacerbated by higher order current components and flicker noise up-conversion, particularly at low supply voltages and high current consumptions.
Innovation Solution
A transformer-based resonator circuit is designed with different inductive coupling factors in differential and common mode excitations, allowing for a resistive path for second harmonics and independent resonance frequencies, thereby mitigating the Groszkowski effect and improving frequency stability and phase noise performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transformer-based resonator circuit is used with different inductive coupling factors in differential and common mode excitations, then phase noise performance is improved by trapping second harmonics in a resistive path, but device complexity increases
Solution Approach 1:
The resonator circuit is segmented into differential mode and common mode excitation paths with different inductive coupling factors. The transformer is divided into primary and secondary windings with specific coupling characteristics for each mode, allowing independent optimization of phase noise performance while managing complexity through functional segmentation.
Solution Approach 2:
Different inductive coupling factors are applied locally to differential and common mode excitations. The transformer exhibits strong coupling for differential mode to trap second harmonics in the resistive path, while common mode coupling is configured differently. This local differentiation of coupling characteristics enables targeted phase noise improvement without uniformly increasing complexity across all circuit operations.
2Reliability
If resistors are added in series with the sources of the transistors for linearizing the operation, then higher order drain current harmonics are reduced, but the radio frequency oscillator start-up margin is reduced
Solution Approach 1:
The transformer-based resonator circuit acts as an intermediary between the transistor sources and the second harmonic path. Instead of directly adding resistors that would reduce start-up margin, the transformer provides a coupled path that presents a resistive characteristic to second harmonics while maintaining the necessary energy transfer for oscillator start-up. This intermediary approach achieves harmonic reduction without the direct penalty of reduced start-up margin.
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 transformer-based resonator circuit effectively reduces flicker noise up-conversion and enhances phase noise performance by trapping second harmonics in a resistive path, improving frequency stability and phase noise characteristics in RF oscillators.
Implementation Method 1
a transformer comprising a primary winding and a secondary winding, wherein the primary winding is inductively coupled with the secondary winding
Implementation Method 2
the primary capacitor and the primary winding forming a primary circuit, and a secondary capacitor being connected to the secondary winding, the secondary capacitor and the secondary winding forming a secondary circuit
Data Source
AI summary
The invention relates to a resonator circuit, the resonator circuit comprising a transformer comprising a primary winding and a secondary winding, wherein the primary winding is inductively coupled with the secondary winding, a primary capacitor being connected to the primary winding, the primary capacitor and the primary winding forming a primary circuit, and a secondary capacitor being connected to the secondary winding, the secondary capacitor and the secondary winding forming a secondary circuit, wherein the resonator circuit has a common mode resonance frequency at an excitation of the primary circuit in a common mode, wherein the resonator circuit has a differential mode resonance frequency at an excitation of the primary circuit in a differential mode, and wherein the common mode resonance frequency is different from the differential mode resonance frequency.