Die-to-Die I/O Clipper Circuit for Overshoot and Undershoot
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Solution Overview
Problem
High-density die-to-die interconnects in IC packaging lead to overshoot and undershoot due to under-damping characteristics, which degrade signal reliability and stability.
Innovation Solution
A high-speed I/O circuit is designed with a data reception circuit that includes a reception circuit, a first clipper circuit for suppressing overshoot via current extraction, and a second clipper circuit for suppressing undershoot via current supply, thereby stabilizing signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-density die-to-die interconnects are used to increase bandwidth, then transmission bandwidth is improved, but overshoot and undershoot occur due to under-damping characteristics
Solution Approach 1:
A damping circuit is introduced as an intermediary component between the interconnect and the reception circuit. This damping circuit includes a damping resistor connected in parallel with the reception circuit, which acts as a mediator to absorb excess energy and suppress the oscillations (overshoot and undershoot) caused by under-damping characteristics of the high-density interconnect, thereby maintaining signal stability while preserving high bandwidth
Solution Approach 2:
The damping characteristics of the transmission system are modified by changing the resistance parameter. A damping resistor with a specific resistance value is added to adjust the overall damping ratio of the system, transforming the under-damped response into a critically damped or over-damped response, which eliminates overshoot and undershoot while maintaining acceptable signal transmission quality
2Reliability
If RCH is excessively large to reduce overshoot, then damping characteristics improve, but the eye-diagram of signal reception is reduced
Solution Approach 1:
Instead of uniformly increasing resistance throughout the transmission line (which would degrade signal quality), the damping resistor is placed locally at the reception end in parallel with the reception circuit. This localized damping approach provides the necessary damping effect to suppress overshoot and undershoot while minimizing the impact on the overall signal transmission characteristics and eye-diagram quality
3Productivity
If LCH and CCH influence is increased for higher density interconnects, then interconnect density is improved, but under-damping characteristics increase causing overshoot and undershoot
Solution Approach 1:
The damping circuit serves as an intermediary that compensates for the under-damping effects introduced by high LCH and CCH values in dense interconnects. The damping resistor absorbs the excess energy from the oscillating signal caused by the interaction of inductance and capacitance in high-density interconnects, preventing overshoot and undershoot while allowing the interconnect density to be maintained
Data Source
AI summary
Disclosed herein is a high-speed I/O circuit for die-to-die interconnect for suppressing an overshoot and an undershoot. A data reception circuit includes a reception circuit configured to convert a reception signal received from an interconnect into a digital signal, a first clipper circuit configured to suppress an overshoot of the reception signal based on current extraction, and a second clipper circuit configured to suppress an undershoot of the reception signal based on current supply.