Inductive Coupling Resonant Circuit Tuning for 3D-IC Stacks
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Solution Overview
Problem
In inductively-coupled 3D integration, the presence of additional non-target dice in a stack reduces the data rate and increases power requirements due to unwanted current induction in receiving inductors, limiting the number of dice that can be stacked effectively.
Innovation Solution
Implementing resonant circuits with adjustable capacitive elements to tune the frequency of resonance, allowing targeted receivers to remain in a tuned state while non-target receivers are detuned, thereby maximizing magnetic flux linkage and optimizing communication efficiency between dice.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If additional non-target dice are stacked in the 3D integration, then device density is increased, but current is induced in non-target receiving inductors reducing data rate and increasing power requirements
Solution Approach 1:
The patent applies local quality by making each receiving inductor have different resonant frequency characteristics tailored to its position in the stack. Non-target inductors are detuned to have resonant frequencies different from the transmit frequency, while the target inductor is tuned to match the transmit frequency. This selective frequency tuning ensures that only the target inductor efficiently receives the magnetic signal, preventing unwanted current induction in non-target inductors and maintaining high data rates even with additional dice stacked.
2Quantity of substance
If additional non-target dice are stacked in the 3D integration, then device density is increased, but power requirements increase for a given bit error rate
Solution Approach 1:
The patent implements local quality through position-dependent resonant frequency tuning of receiving inductors. Each inductor's resonant frequency is locally optimized based on its location in the stack relative to the transmitter. Non-target inductors are detuned to minimize their response to the transmit frequency, reducing the power needed to achieve the desired signal-to-noise ratio at the target inductor. This eliminates the need to increase transmit power to compensate for interference from additional stacked dice.
3Reliability
If resonant circuits are tuned to transmit frequency, then magnetic flux linkage is maximized, but current is induced in non-target inductors reducing communication efficiency
Solution Approach 1:
The patent applies local quality by assigning different resonant frequencies to different receiving inductors based on their position in the stack. The target inductor is tuned to match the transmit frequency for maximum magnetic flux linkage and efficient communication. Non-target inductors are detuned to have resonant frequencies different from the transmit frequency, which minimizes their response to the transmitted magnetic field and prevents unwanted current induction. This selective tuning resolves the contradiction by making each inductor's resonant characteristic locally optimized for its specific role.
4Reliability
If TSVs are used for interconnection, then vertical communication is achieved, but post-fabrication processing and strict alignment are required increasing manufacturing cost
Solution Approach 1:
The patent replaces the mechanical TSV interconnection system with a wireless magnetic coupling system. Instead of using physical through-silicon vias that require precise mechanical alignment and post-fabrication processing, the invention uses inductively coupled resonant circuits to transmit signals vertically through the stack. The magnetic field coupling between transmitter and receiver inductors eliminates the need for physical contact and strict alignment, significantly simplifying the manufacturing process while maintaining reliable vertical communication.
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 approach reduces the transmit power required for a given Bit Error Rate, enhances data rate, and enables communication with a greater number of dice in a 3D-IC stack without the need for post-fabrication processing or strict die-to-die alignments, thus reducing manufacturing costs.
Implementation Method 1
Data is encoded in a series of current pulses which are fed through a planar inductor fabricated in the upper back-end-of-line (BEOL) interconnect layers of the transmitting die. These current pulses generate a magnetic field which is intersected by similar receiving inductors, fabricated in neighboring dice. This induces a current in the receiving inductors
Implementation Method 2
Implementing resonant circuits with adjustable capacitive elements to tune the frequency of resonance, allowing targeted receivers to remain in a tuned state while non-target receivers are detuned, thereby maximizing magnetic flux linkage and optimizing communication efficiency between dice
Data Source
AI summary
The present disclosure provides a method and apparatus for communicating between dice of an inductively-coupled 3D integrated circuit (3D-IC). A transmit resonant circuit at a transmit die is inductively coupled to a first receive resonant circuit at a first receive die, and to a second receive resonant circuit at a second receive die. The resonant circuit at the targeted receive die is tuned to the frequency of resonance of the transmit resonant circuit, while the resonant circuit at the untargeted receive die is detuned, resulting in lower power consumption for a given bit error rate at the targeted die.