FPGA Clock Frequency Ramping to Limit Inrush Current and IR Drop
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Solution Overview
Problem
Integrated circuits with programmable logic circuitry, such as FPGAs, experience a significant current-resistance (IR) drop during transitions between configuration and user modes due to inrush current, leading to inefficiencies and potential damage, which are exacerbated by conventional guardbanding solutions that compromise performance and increase design costs.
Innovation Solution
Gradually ramping the clock frequency from the configuration mode to the user mode using a phase-locked loop or digitally-locked loop to reduce the inrush current and associated IR drop, allowing for reduced guardbands and optimized performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the clock frequency is rapidly changed from configuration mode to user mode, then the transition time is reduced, but the inrush current and IR drop increase significantly
Solution Approach 1:
The patent applies dynamics by making the clock frequency change adaptive rather than fixed. The frequency transition is dynamically adjusted based on the detected IR drop level, allowing the system to optimize between transition speed and current management in real-time during the mode change from configuration to user mode.
Solution Approach 2:
The patent changes the clock frequency parameter during the transition process. Instead of maintaining a fixed frequency or using a simple fixed-step change, the system modifies the frequency parameter dynamically based on monitored electrical conditions (IR drop), enabling optimized transition performance that balances speed and current consumption.
2Reliability
If guardbands are increased to accommodate inrush current and IR drop, then the reliability is improved, but the performance and space constraints are worsened
Solution Approach 1:
The patent implements feedback by monitoring the actual IR drop during the clock frequency transition and using this information to adjust the transition process. This closed-loop approach allows the system to maintain reliability by detecting problematic conditions while avoiding excessive guardbands, thereby preserving performance and meeting space constraints.
Solution Approach 2:
The patent performs preliminary monitoring of IR drop conditions before completing the full mode transition. By detecting early signs of excessive current or voltage drop during the frequency ramping process, the system can adjust the transition parameters in advance to prevent reliability issues without requiring large performance margins.
3Object-generated harmful factors
If the clock frequency is ramped gradually to reduce inrush current, then the IR drop is reduced, but the transition time increases
Solution Approach 1:
The patent makes the ramping process dynamic by adjusting the frequency change rate based on real-time IR drop measurements. Instead of using a fixed slow ramp rate for all conditions, the system accelerates or decelerates the frequency transition dynamically, achieving fast transitions when conditions permit and slower transitions when current management is critical.
Solution Approach 2:
The patent changes the transition parameters (frequency step size, ramp rate) based on monitored electrical conditions. The system adjusts these parameters during the transition process to optimize between speed and current management, rather than using a predetermined fixed transition profile.
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
The method reduces inrush current and IR drop, enabling faster configuration times, improved performance, and lower power consumption by minimizing the need for larger power supplies and relaxed design constraints.
Implementation Method 1
Gradually ramping the clock frequency from the configuration mode to the user mode using a phase-locked loop or digitally-locked loop to reduce the inrush current and associated IR drop
Data Source
AI summary
Systems or methods of the present disclosure may provide for gradually adjusting a frequency of a clock signal. When transitioning from a configuration mode to a user mode, a clock of an integrated circuit (e.g., a field-programmable gate array or FPGA) may quickly (e.g., instantaneously) switch from a low configuration mode frequency to a high user mode frequency. This rapid increase in clock frequency may cause an inrush current and corresponding current-resistance voltage (IR) drop. To reduce or avoid the inrush current and IR drop, a frequency of the clock may be gradually ramped up from the configuration mode frequency to the user mode frequency.