Clock Distribution Circuit With Active Impedance Reduction for Jitter
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Solution Overview
Problem
Conventional clock distribution circuits suffer from high power consumption, impedance mismatch, and jitter amplification due to large buffers, leading to increased jitter and edge rate degradation, which existing termination methods fail to address effectively.
Innovation Solution
Implementing an active impedance reduction circuit with a feedback configuration using a series resistor and auxiliary clock buffer to reduce noise at the input of inverters, thereby lowering frequency-dependent impedance and improving signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If large buffers are used in clock distribution circuits, then signal driving capability is improved, but impedance mismatch and jitter amplification increase
Solution Approach 1:
The patent applies local quality by implementing termination circuits at specific locations where impedance matching is needed, rather than uniformly across the entire clock distribution network. The termination resistance is locally applied at buffer outputs to match impedance, while other parts of the circuit maintain their original characteristics.
Solution Approach 2:
The patent introduces termination resistors as intermediary elements between the buffer output and the clock distribution network. These resistors act as mediators to match impedance levels, reducing reflections and jitter amplification while allowing the buffer to maintain its driving capability.
2Reliability
If conventional termination methods are applied, then impedance matching is improved, but power consumption increases
Solution Approach 1:
The patent applies partial termination rather than full termination across the entire clock distribution network. By selectively applying termination resistance only at critical points (buffer outputs), the patent achieves sufficient impedance matching while avoiding the excessive power consumption that would result from terminating all clock lines.
Solution Approach 2:
The termination is applied locally at specific points in the clock distribution network where impedance matching is most critical, rather than uniformly throughout. This localized approach reduces overall power consumption while maintaining impedance matching where it provides the most benefit.
3Length of stationary object
If clock signals are distributed over long distances, then coverage area is improved, but jitter and edge rate degradation increase
Solution Approach 1:
The patent introduces termination resistors as intermediary elements at buffer output stages to match impedance and reduce signal reflections. This mediation allows clock signals to be distributed over longer distances with reduced jitter and edge rate degradation by preventing signal integrity issues that would otherwise accumulate over distance.
Solution Approach 2:
The patent implements feedback mechanisms through the termination circuits that reflect and dampen unwanted signal variations. The termination resistance provides a feedback path that reduces the impact of reflections and noise, allowing stable clock distribution over extended distances without significant jitter accumulation.
Data Source
AI summary
Embodiments of the invention relate to a clock generation and distribution circuit (“clock circuit”) according to various embodiments of the present disclosure. The clock circuit comprises active impedance reduction circuits which improves bandwidth and jitter performance of the clock circuit by lowering the small-signal impedance within the clock circuit. In certain embodiments, an activation element is positioned at a node along a transmission path to cause a reduction in impedance.