Frequency Divider Tuning for Low-Phase-Noise Oscillators
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Solution Overview
Problem
Existing frequency tunable arrangements face challenges in achieving low phase noise across a wide frequency range, requiring high-quality frequency-determining elements that increase costs, and often necessitate external inductance components.
Innovation Solution
A frequency tunable arrangement with a controllable frequency divider circuit that provides division factors with a ratio not exceeding 1.25 to the closest lower factor, allowing a tunable oscillator to operate within a smaller frequency range with modest-quality frequency-determining elements, such as integrated circuit substrate inductance and capacitance, reducing costs and electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a wide frequency range is achieved using a single tunable oscillator, then the tuning range increases, but the phase noise deteriorates
Solution Approach 1:
The wide frequency range is segmented into multiple sub-ranges, each handled by a separate local oscillator with a limited tuning range (ratio not exceeding 1.25). This segmentation allows each oscillator to maintain low phase noise while the system as a whole achieves wide frequency coverage through the frequency divider circuit.
Solution Approach 2:
A frequency divider circuit is introduced as an intermediary between the local oscillator and the mixing stage. This mediator enables the oscillator to operate at a lower, more stable frequency while still achieving the required high frequency output, thereby reducing phase noise without limiting the overall tuning range.
2Reliability
If high-quality frequency-determining elements are used to reduce phase noise, then the phase noise improves, but the cost increases
Solution Approach 1:
The operating parameters of the frequency-determining elements are optimized by limiting the tuning range ratio to not more than 1.25. This parameter change allows the use of lower-quality (and thus lower-cost) inductors and capacitors while maintaining acceptable phase noise performance across the segmented frequency ranges.
Solution Approach 2:
By segmenting the frequency range and using a frequency divider, the system can achieve wide frequency coverage without requiring high-quality frequency-determining elements across the entire range. Each oscillator only needs to maintain stability over a limited range, reducing the quality requirements and cost of the inductors and capacitors.
3Device complexity
If a single oscillator covers the entire frequency range, then the device complexity is reduced, but the phase noise deteriorates
Solution Approach 1:
The oscillator system is segmented into multiple local oscillators, each covering a specific frequency sub-range. This segmentation increases the number of oscillator circuits but allows each to operate with lower phase noise, and the frequency divider circuit manages the complexity by selecting and dividing the appropriate oscillator output for each frequency band.
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 solution enables low phase noise performance across a wide frequency range using cost-efficient, high-quality frequency-determining elements, reducing overall costs and eliminating the need for external inductance components, while maintaining satisfactory reception quality.
Implementation Method 1
A controllable frequency divider circuit provides a frequency-divided signal on the basis of the oscillator signal. The frequency-divided signal has a frequency that is equal to the frequency of the oscillator signal divided by a division factor.
Data Source
AI summary
A frequency tunable arrangement (ICT) comprises a tunable oscillator circuit (TOC) that provides an oscillator signal (OS). A controllable frequency divider circuit (CDIV, DBT1, DBT2, DBT3, MUX) provides a frequency-divided signal (MO) on the basis of the oscillator signal. The frequency-divided signal has a frequency that is equal to the frequency of the oscillator signal divided by a division factor. The controllable frequency divider circuit provides any division factor among a set of division factors (4, 5, 6, 7, 8) in which for any division factor a ratio between that division factor and a lower division factor closest thereto, if existing, does not exceed 1.25.