Shared Ring Oscillator Calibration for Die-to-Die Transmitters
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Solution Overview
Problem
Existing interconnect architectures in high-performance computing systems face challenges in efficiently managing the increasing demand for higher processing rates, leading to communication bottlenecks between sockets and devices.
Innovation Solution
The proposed solution involves determining calibration information for transmitter circuitry based on characteristics of a ring oscillator circuit formed with two integrated circuit (IC) dies, which allows for the detection and compensation of impedance variations between dies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If interconnect architectures are used to facilitate fast communication between sockets and devices, then communication speed is improved, but impedance variations between IC dies cause eye margin loss and communication reliability deteriorates
Solution Approach 1:
The patent applies preliminary action by performing calibration of transmit driver circuitry before actual high-speed communication occurs. The system determines calibration information using ring oscillator characteristics and impedance measurements in advance, then applies this calibration data to adjust driver circuit parameters. This preliminary calibration ensures that when high-speed communication begins, the system is already optimized and compensated for impedance variations, preventing eye margin loss rather than reacting to it afterward.
Solution Approach 2:
The patent implements feedback by measuring actual impedance values between IC dies using ring oscillator circuits and using this measurement information to adjust transmit driver circuitry parameters. The system continuously monitors communication quality metrics such as eye margin and uses this feedback to refine calibration settings. This closed-loop feedback mechanism allows the system to adapt to real-world impedance variations and maintain reliable high-speed communication despite manufacturing tolerances and environmental changes.
2Productivity
If multiple IC dies are coupled to increase processing power, then computing capability is improved, but impedance variations between dies cause communication bottlenecks
Solution Approach 1:
The patent applies local quality by providing individualized calibration for each transmit driver circuit based on its specific interconnect characteristics. Instead of using a uniform calibration approach for all IC dies, the system measures impedance variations specific to each die-to-die connection and applies targeted calibration adjustments. This localized calibration approach ensures that each communication channel is optimized for its specific electrical characteristics, eliminating communication bottlenecks that would arise from generic calibration settings.
Solution Approach 2:
The patent implements parameter changes by adjusting transmit driver circuitry parameters such as output impedance, signal amplitude, and timing based on measured interconnect characteristics. The system modifies these electrical parameters dynamically to compensate for impedance variations between different IC die combinations. By changing these parameters based on actual measurements rather than fixed design values, the system maintains optimal communication rates across multiple coupled dies despite manufacturing variations.
3Device complexity
If traditional multi-drop buses are used for electrical communication, then device complexity is reduced, but communication efficiency deteriorates under high processing rates
Solution Approach 1:
The patent applies preliminary action by performing comprehensive calibration measurements and determining optimal operating parameters before high-speed communication begins. The system uses ring oscillator circuits to measure impedance characteristics and determine calibration information in advance, then applies this pre-determined calibration data to configure transmit driver circuitry. This preliminary setup phase, though adding some initial complexity, enables the system to achieve high communication efficiency without requiring complex real-time adjustment mechanisms during actual data transmission.
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 enables effective calibration of transmit driver circuitry, improving communication efficiency and reducing eye margin loss due to impedance variations, thereby enhancing overall system performance.
Implementation Method 1
a first operational setting of a ring oscillator circuit is determined
Implementation Method 2
calibration information is determined by a first IC die, based on both a tuning of the ring oscillator circuit and an impedance between the first IC die and a second IC die
Data Source
AI summary
Techniques and mechanisms for determining calibration information based on tuning of a ring oscillator circuit formed with two integrated circuit (IC) dies. In an embodiment, an oscillator circuit comprises an in-series arrangement of delay circuits including a first one or more delay circuits of a first die, and a second one or more delay circuits of a second die. Respective circuitry of the first die and the second die performs tuning to match an oscillation frequency of the oscillator circuit with a reference frequency. An operational setting of the tuned oscillator circuit is provided to calibrate transmitter circuitry of the first die and the second die. In another embodiment, tuning of the oscillator circuit is further based on tuning of a local oscillator circuit of one of the first die or the second die.