Clock Pulse Generator Isolation for Slew-Tolerant Latching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional clock pulse generators face issues with timing marginalities and slew rate sensitivity, leading to error conditions when generating internal clock signals, particularly when dealing with varying slew rates and propagation delays in synchronous digital logic systems.
Innovation Solution
The proposed solution involves a clock pulse generator circuit with an isolation buffer and control circuit that latches logic values based on leading edges, isolates the latched values from input changes, and resets them after a delay, ensuring the internal clock signal is generated accurately regardless of input slew rates, using a system block diagram and timing diagrams to illustrate the operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional clock pulse generators are used to generate internal clock signals, then the system can operate with standard clock generation, but timing marginalities and slew rate sensitivity cause error conditions
Solution Approach 1:
The isolation buffer is enabled before the clock edge arrives at the latch, pre-establishing the isolated path so that when the clock edge arrives, the latch is already protected from input slew variations. This preliminary enabling of the isolation buffer eliminates timing marginalities by ensuring the isolation path is ready in advance.
Solution Approach 2:
The isolation buffer acts as an intermediary between the latch and the input signals (clock and enable). It buffers the latched value to prevent direct coupling with input slew variations, thereby eliminating slew rate sensitivity and timing marginalities that would otherwise cause error conditions.
2Reliability
If the latch is directly coupled to input signals for immediate response, then the circuit is simple, but changes at the input continue to affect the latched value causing errors
Solution Approach 1:
The isolation buffer serves as an intermediary element inserted between the latch output and the input signal path. This additional component isolates the latched value from subsequent input changes, ensuring accurate latching while accepting the necessary increase in circuit complexity.
Solution Approach 2:
The circuit is segmented into distinct functional blocks: the latch unit, the isolation buffer unit, and the control logic unit. This segmentation allows the isolation buffer to be independently inserted to provide latching protection without redesigning the entire circuit, managing complexity through modular organization.
3Reliability
If the isolation path is enabled continuously, then the latch is always protected from input changes, but the enable signal cannot be properly synchronized with the clock edge
Solution Approach 1:
The isolation buffer is enabled in advance of the clock edge, but not continuously. The control logic enables the isolation path at a specific time before the expected clock arrival, providing protection only when needed. This preliminary timing enables synchronization while maintaining latch protection during critical periods.
Solution Approach 2:
The isolation buffer enable signal is activated periodically in synchronization with the clock edge timing rather than continuously. This periodic enabling occurs at precise intervals aligned with clock cycles, reducing unnecessary activation while ensuring protection during each critical latching window.
Data Source
AI summary
According to an embodiment, a method of generating a clock pulse includes receiving a leading edge at a clock input at a time when an enable signal is active, generating an edge at a clock output based on the received leading edge at the clock input, latching a logic value corresponding to the edge at the clock output, preventing changes at the clock input from affecting the latched logic value after the logic value is latched, resetting the latched logic value after a first delay time, and maintaining the reset logic value until a second edge is received at the clock input. The second edge at the clock input matches the leading edge at the clock input.