Main Oscillator Structure for Low-Jitter Counter-Controlled Delay Lines
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Solution Overview
Problem
Conventional tap-controlled delay lines are sensitive to environmental and operating conditions, leading to jitter in clock signals, occupy large area, and introduce duty cycle distortion, making them inefficient for high-frequency applications.
Innovation Solution
A counter-controlled delay line that uses an oscillator with an adjustable start point and a counter to provide medium and coarse grain delay adjustments, along with a trim unit for fine grain adjustments, reducing the number of taps required and minimizing area while maintaining high frequency range support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a tap-controlled delay line is used to delay clock signals, then delay adjustment capability is provided, but the circuit occupies large area and introduces duty cycle distortion
Solution Approach 1:
The patent replaces the mechanical tap-controlled delay line structure with a counter-controlled delay line that uses digital counting and control logic. Instead of physically selecting taps through complex switching networks, the invention uses a counter to generate delay control signals, substituting a simpler digital control mechanism for the complex analog/digital tap selection hardware, thereby reducing circuit area while maintaining delay adjustment capability
Solution Approach 2:
The patent changes the control parameter from tap selection (analog/digital hybrid) to counter value (pure digital). By using a counter that increments with each clock cycle and comparing its value against a threshold, the delay line achieves precise delay control through digital parameter manipulation rather than physical tap switching, reducing area and improving duty cycle performance
2Adaptability or versatility
If a tap-controlled delay line is used to provide delay, then delay functionality is achieved, but jitter is introduced due to sensitivity to environmental conditions
Solution Approach 1:
The patent substitutes the environmentally sensitive tap-controlled mechanism with a counter-controlled digital system. The counter increments synchronously with the clock signal and uses digital comparison logic to control the delay, replacing analog/digital hybrid tap selection with pure digital control that is immune to environmental variations, thereby eliminating jitter while maintaining delay functionality
Solution Approach 2:
The counter-controlled delay line uses the clock signal itself to drive the counter, creating a self-synchronized system. The counter automatically increments with each clock edge and self-regulates the delay control signals without external intervention, ensuring that the delay mechanism is inherently synchronized to the clock and free from environmental jitter
3Adaptability or versatility
If more taps are added to a delay line to support higher frequency range, then frequency adaptability increases, but device complexity and area increase
Solution Approach 1:
The patent replaces the physical tap structure with a counter-based control system. Instead of adding more physical taps to extend frequency range, the invention uses a counter that can be programmed with different threshold values to accommodate different frequency ranges. This digital parameter adjustment replaces physical expansion, maintaining low complexity while achieving high frequency adaptability
Solution Approach 2:
The patent makes the delay line dynamically adaptable through a programmable counter threshold. Rather than having fixed taps for specific delay values, the counter threshold can be dynamically adjusted to match different operating frequencies and delay requirements, providing flexible frequency range support without increasing the number of physical taps or circuit complexity
Data Source
AI summary
A counter-controlled delay line includes a main oscillator for delaying edges of an input signal to generate a main clock signal. The main oscillator includes a plurality of gated delay elements connected in a ring. Each gated delay element includes a first control terminal to receive a corresponding load signal, and includes a second control terminal to receive a release signal. The release signal may simultaneously enable and disable state transitions in all delay elements, and the load signals may simultaneously drive an output of each delay element to any selected logic state.