Latch-Based Clock Multiplexer Without Extra Clock Cycles
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Solution Overview
Problem
Conventional clock multiplexers introduce glitches and inefficiencies when switching between clock signals, leading to erroneous operations and performance issues due to the output of extra clock cycles and reliance on multiple AND gates, which also causes the circuit to stop functioning if either clock signal stops.
Innovation Solution
A clock multiplexer design utilizing two input stages with flip-flops and latches, connected through AND and OR gates, which outputs only a half clock cycle of the first signal and transitions smoothly to the second signal, reducing circuit area by using only two AND gates and ensuring continuous operation even if one clock signal fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional clock multiplexer uses multiple AND gates to eliminate glitches, then glitch-free operation is achieved, but circuit area increases and complexity increases
Solution Approach 1:
The clock multiplexer is divided into two independent input stages, each handling one clock signal path. Each input stage includes its own flip-flop, latch, and AND gate configuration, allowing independent operation and reducing the need for cross-coupling gates between stages.
Solution Approach 2:
A latch is introduced as an intermediary element between the flip-flop and the AND gate in each input stage. This latch acts as a buffer that stabilizes the enable signal before it reaches the AND gate, preventing glitch propagation without requiring additional AND gates for glitch elimination.
2Reliability
If a conventional clock multiplexer uses multiple AND gates to prevent glitches, then reliable clock switching is achieved, but circuit area increases
Solution Approach 1:
The circuit is segmented into two independent input stages, each requiring only one AND gate. This segmentation reduces the total AND gate count from four (in conventional designs) to two, directly reducing circuit area while maintaining reliable clock switching through independent stage operation.
Solution Approach 2:
Each input stage is self-sufficient with its own flip-flop, latch, and AND gate combination. The latch in each stage self-regulates the enable signal timing, eliminating the need for additional AND gates from other stages to prevent glitches, thus reducing overall circuit area.
3Stability of the object's composition
If a clock multiplexer outputs extra clock cycles during switching, then smooth transition is achieved, but productivity decreases due to wasted clock cycles
Solution Approach 1:
The latch in each input stage performs preliminary action by pre-stabilizing the enable signal before it reaches the AND gate. This preliminary stabilization ensures that the clock signal is enabled or disabled precisely at the intended transition point, preventing extra clock cycles from being output during switching while maintaining smooth transitions.
Solution Approach 2:
The latch provides feedback control on the enable signal timing. By monitoring the clock signal edges and adjusting the enable signal timing accordingly, the latch ensures that clock switching occurs exactly when intended, eliminating wasted clock cycles while maintaining transition smoothness.
4Adaptability or versatility
If a conventional clock multiplexer relies on multiple clock signals for operation, then comprehensive clock control is achieved, but reliability decreases when one clock signal stops
Solution Approach 1:
The clock multiplexer is segmented into two independent input stages, each capable of independent operation. If one clock signal stops, its corresponding input stage simply becomes inactive while the other stage continues to function normally, ensuring operation continuity without affecting the entire system.
Solution Approach 2:
The independent stage architecture ensures that useful action continues in the functioning stage even when one clock signal stops. The non-faulty stage maintains uninterrupted clock output, providing continuous useful action to the system without being halted by failures in the other clock signal.
Data Source
AI summary
A clock multiplexer includes first and second input stages for outputting first and second clock signals, respectively. The first and second input stages each include a flip-flop, a latch and a first logic gate. Reset terminals of the flip-flops receive a select signal based on which the first and second input stages output the first and second clock signals. A second logic gate is connected to the first and second input stages for selectively providing the first and second clock signals as an output clock signal.