Adaptive VCO Tail Filter Tuning for Lower Flicker and Phase Noise
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Solution Overview
Problem
Existing wireless communication devices face challenges in reducing flicker noise upconversion and phase noise in signal oscillation circuits, particularly in variable-frequency oscillators like VCOs, which affect the signal-to-noise ratio and overall performance.
Innovation Solution
A signal oscillation circuit with adaptive tuning for tail filters, incorporating a VCO and logic circuitry that generates a training signal to determine phase differences and automatically tune tail filters to minimize upconversion gain, thereby reducing flicker noise and phase noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional fixed tail filters are used in VCO, then circuit structure is simple, but flicker noise upconversion and phase noise cannot be effectively reduced
Solution Approach 1:
The patent applies dynamics by making the tail filter tunable rather than fixed. The tail filter's resonant frequency can be dynamically adjusted to track and cancel flicker noise at different VCO operating frequencies, effectively reducing flicker noise upconversion while maintaining manageable circuit complexity through systematic design
Solution Approach 2:
The patent changes the parameter of tail filter resonant frequency to match the VCO operating frequency. By adjusting the tail filter's resonant frequency parameter to track the VCO frequency, the system achieves effective flicker noise reduction across a wide frequency range without requiring overly complex circuit architecture
2Object-affected harmful factors
If adaptive tail filter tuning is implemented, then phase noise is reduced, but device complexity increases
Solution Approach 1:
The patent implements feedback by using a portion of the VCO output signal to control the tail filter tuning. The tail filter is automatically adjusted based on the VCO's operating frequency, creating a closed-loop system that reduces phase noise while keeping the tuning mechanism relatively simple through direct frequency coupling
Solution Approach 2:
The patent achieves universality by designing the tail filter to serve multiple functions: it acts as both a noise filtering element and a frequency-tracking element. The same tail filter structure handles both flicker noise reduction and phase noise reduction across different operating frequencies, reducing the need for additional separate tuning components
3Object-affected harmful factors
If tail filter resonant frequency matches VCO frequency, then noise reduction is maximized, but circuit design complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the tail filter's resonant frequency to match the VCO's operating frequency before operation. The tail filter is designed with predetermined capacitance and inductance values that establish the correct resonant frequency relationship, eliminating the need for complex real-time frequency matching mechanisms during operation
Data Source
AI summary
Techniques and apparatus for oscillating signal generation using a signal oscillation circuit capable of adaptively tuning one or more tail filters. An example signal oscillation circuit generally includes a voltage-controlled oscillator (VCO) that includes a VCO core and a first tail filter coupled to the VCO core, the first tail filter including a tunable component, a logic circuit including a first output coupled to a control input of the tunable component of the first tail filter, and a first signal converter including an input coupled to a second output of the logic circuit and including an output coupled to a node of the VCO.