Digital Ring Oscillator Delay Path Switching for Low-Jitter Tuning
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Solution Overview
Problem
Conventional oscillators, such as voltage-controlled oscillators, rely on analog circuits and quartz crystals, which consume space, power, and are sensitive to temperature variations, making them undesirable for modern digital devices that require compact, noise-resistant, and easily integratable solutions.
Innovation Solution
A digitally-controlled ring oscillator using standard digital library blocks with a multiplexor and flip-flop circuitry that allows for adjustable period and low jitter operation, suitable for automatic layout tools and capable of selective mode control, reducing board circuitry and noise sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional voltage-controlled oscillators use analog circuits and quartz crystals, then stable frequency generation is achieved, but circuit area increases, power consumption increases, and temperature sensitivity worsens
Solution Approach 1:
The patent replaces the mechanical quartz crystal oscillator with a digitally-controlled ring oscillator using standard digital logic cells (inverters, NAND gates, NOR gates). This substitution eliminates the need for analog circuits and quartz crystals while achieving frequency control through digital delay elements, thereby reducing circuit area and power consumption while maintaining frequency stability
Solution Approach 2:
The patent uses digitally controllable delay elements where the delay parameter can be adjusted through digital control signals. By changing the delay parameter of individual stages in the ring oscillator, the overall oscillation frequency can be precisely controlled without requiring analog voltage control, thus achieving both frequency stability and digital controllability
2Adaptability or versatility
If conventional oscillators use analog circuits, then frequency control is achieved, but integration with digital circuits becomes difficult and design complexity increases
Solution Approach 1:
The patent creates a universal oscillator design that can be integrated with both digital and mixed-signal circuits. By using standard digital logic cells that can be found in any digital library, the oscillator becomes a multi-functional building block that adapts easily to different digital circuit architectures without requiring separate analog design processes
Solution Approach 2:
The ring oscillator is divided into multiple identical delay stages, each implemented with standard digital logic cells. This segmentation allows the oscillator to be constructed using repetitive modular units, simplifying the design process and enabling easy integration with digital circuits while reducing overall design complexity
3Measurement precision
If quartz crystals are used for frequency control, then accurate frequency generation is achieved, but power consumption increases and temperature sensitivity worsens
Solution Approach 1:
The patent replaces the quartz crystal mechanical resonator with a digital ring oscillator that consumes significantly less power. The digital logic-based oscillation mechanism eliminates the high power requirements of quartz crystals while maintaining frequency accuracy through precise digital delay control in each stage
4Ease of operation
If analog circuits are used in oscillators, then frequency control is achieved, but noise sensitivity increases and board circuitry requirements increase
Solution Approach 1:
The patent substitutes analog voltage-controlled delay elements with digitally controlled delay elements implemented using standard logic gates. This substitution makes the oscillator inherently resistant to noise and eliminates the need for careful analog PCB layout, simplifying board circuitry requirements while improving noise resistance
Data Source
AI summary
A ring oscillator for generating an output signal, comprising a plurality of serially connected main elements for selectively delaying a signal input thereto, each of the plurality of main elements having two circuit paths, a first path including at least one time-delay element for delaying a signal input thereto and a second circuit path bypassing the first circuit path; and a multiplexor (MUX) having a first input coupled to the first circuit path including the at least one time-delay element and a second input coupled to the second circuit path, the MUX selecting the first or second inputs of a plurality of inputs and outputting an output signal.