Apparatus and method for reduced latency signal synchronization
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Solution Overview
Problem
Current signal synchronization methods for integrated circuits face challenges in reducing latency and addressing state stability issues when synchronizing signals between asynchronous clock domains, particularly with increasing clock frequencies, leading to performance degradation and logic failures.
Innovation Solution
The proposed solution involves an apparatus and method that uses selection, resolution, arbiter, and latching circuitry to generate intermediate signals, resolve meta-stability, and determine dominant values, thereby reducing latency and improving signal stability by minimizing circuit stages and addressing meta-stability issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple stages of synchronizing flip-flops are used to synchronize signals to higher frequency clock domains, then synchronization reliability is improved, but latency increases and system performance deteriorates
Solution Approach 1:
The patent introduces a synchronizing signal as an intermediary between the source clock domain and the destination clock domain. This synchronizing signal is generated based on the destination clock and used to control the sampling of input signals, ensuring that data is captured only when timing conditions are satisfied. This intermediary mechanism eliminates the need for multiple cascaded flip-flop stages while maintaining synchronization reliability and reducing latency.
Solution Approach 2:
The patent performs preliminary actions by generating the synchronizing signal in advance based on the destination clock domain timing. The synchronizing signal is prepared beforehand to indicate when it is safe to sample the input signal, ensuring that setup and hold time requirements are met before the actual data capture occurs. This preliminary timing coordination eliminates the need for multiple synchronization stages.
2Reliability
If multiple stages of synchronizing flip-flops are used to meet MTBF requirements, then signal stability is improved, but circuit complexity increases
Solution Approach 1:
The synchronizing signal acts as an intermediary that coordinates between clock domains without requiring multiple complex flip-flop stages. By using this single synchronizing signal mechanism with timing validation logic, the circuit achieves the required MTBF compliance while maintaining simpler circuitry compared to traditional multi-stage synchronizers.
Solution Approach 2:
The patent changes the approach from using multiple sequential flip-flop stages to using a synchronizing signal with timing validation. This parameter change in the synchronization methodology achieves the same reliability goals through a different mechanism that reduces circuit complexity and eliminates the need for multiple FF stages.
3Adaptability or versatility
If input signals change value within setup and hold timing constraints, then signal adaptability is improved, but state stability deteriorates causing logic failures
Solution Approach 1:
The patent applies preliminary anti-action by using the synchronizing signal to prevent invalid sampling of input signals. The synchronizing signal is generated in advance to indicate when timing constraints are satisfied, and the input signal is only sampled when the synchronizing signal permits. This preliminary prevention mechanism blocks potential meta-stable states caused by violating setup and hold time requirements, thereby maintaining signal state stability while still allowing adaptive signal changes when timing conditions are met.
Data Source
AI summary
A circuit to sample an input signal in an asynchronous clock domain. The apparatus includes a first latch configured to favor resolving to a logical high level and a second latch configured to favor resolving to a logical low level. The circuit includes a pullup pMOSFET, and first and second pMOSFETs. The first pMOSFET has a source terminal coupled to the drain terminal of the pullup pMOSFET, a gate coupled to a first input port of the first latch, and a drain terminal coupled to a second output port of the second latch. The second pMOSFET has a source terminal coupled to the drain terminal of the pullup pMOSFET, a gate coupled to the second output port of the second latch, and a drain terminal coupled to the first input port of the first latch.