Clock State Machine With Frequency Ramping for Low-Noise Clock Trees
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Solution Overview
Problem
Integrated circuits face noise issues due to capacitance in clock trees, particularly during clock gating and reset sequencing, which existing noise management techniques are too slow to effectively address in modern devices.
Innovation Solution
Implementing a method to ramp clock signals gradually during state transitions, reducing the rate of frequency change to minimize voltage noise, which can be achieved by forming mechanisms within a microcircuit to adjust clock rates through controlled ramping processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If clock frequency is changed quickly from off state to multiple GHz frequencies, then clock control speed is improved, but voltage noise increases due to high dI/dT
Solution Approach 1:
The patent applies preliminary action by introducing a ramp-up period before the clock reaches its final high frequency. During this period, the clock frequency is gradually increased through intermediate steps rather than jumping directly to the target frequency. This preliminary frequency adjustment reduces the instantaneous dI/dT and prevents voltage noise while still enabling fast clock control overall.
Solution Approach 2:
The patent segments the clock frequency transition into multiple discrete steps or stages. Instead of a single abrupt frequency change, the clock frequency is divided into incremental increases (e.g., from off to low frequency, then to medium frequency, and finally to high frequency). This segmentation allows each transition step to occur with controlled current change, reducing voltage noise while maintaining fast control capability.
2Object-generated harmful factors
If existing noise management techniques are used in clock trees, then voltage noise is reduced, but the techniques are too slow for modern integrated circuit devices
Solution Approach 1:
The patent applies dynamics by making the clock frequency adjustable and time-dependent. The clock system dynamically adapts its frequency based on the current state and timing requirements. This dynamic control allows the system to achieve noise reduction at the precise moment when it is needed, rather than using static or overly conservative frequency limits that would slow down operation.
Solution Approach 2:
The patent changes the clock frequency parameter in a controlled manner during transitions. By systematically adjusting the frequency parameter through predefined ramp-up sequences and intermediate values, the system achieves both noise reduction and fast control. The frequency parameter is modified based on operational requirements, allowing optimal performance without excessive noise.
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 noise generated by clock gating and reset sequencing, thereby improving the performance of integrated circuit devices by allowing fast and complex clock control behaviors while minimizing voltage noise.
Implementation Method 1
One source of voltage noise in modem silicon is the die-to-package inductance. Voltage over an inductance L is equal by definition to V=LdI/dT.
Data Source
AI summary
Methods, apparatus, and fabrication techniques relating to management of noise arising from capacitance in a clock tree of an integrated circuit. In some embodiments, the methods comprise receiving a signal to adjust a clock having a first rate to a second rate; and ramping, in response to receiving the signal, the clock from the first rate to the second rate, wherein the ramping comprises changing the frequency of the clock to at least one third rate between the first and second rates.