Bypass Flip-Flop Circuit for High-Frequency Delay Margin
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Solution Overview
Problem
Conventional bypass flip-flop circuits experience significant signal delivery delay during high-frequency operations due to unnecessary signal paths and large loading caused by large transmission gates, limiting their operating frequency.
Innovation Solution
A flip-flop circuit design that utilizes an input controller, latch portion, and output controller with NOR gates and transmission gates to selectively output data based on bypass and clock signals, eliminating the need for additional inverters and reducing signal path length, thereby improving signal transfer delay margin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a driver is added to provide more stable signal delivery, then signal stability is improved, but signal transmission delay increases due to additional inverter stages
Solution Approach 1:
The patent removes the unnecessary transmission gate T1 from the signal path when bypass mode is activated. By extracting this component from the active signal path, the signal only needs to pass through one transmission gate (T4) and two inverters (IV2, IV3) instead of three inverters and one transmission gate, reducing the total delay from 700ps to approximately 500ps while maintaining signal stability through the bypass mechanism.
Solution Approach 2:
The patent implements dynamic switching between two operational modes using the bypass signal: normal mode where the signal passes through transmission gate T1 and latch R1, and bypass mode where the signal directly passes through transmission gate T4 and inverters IV2-IV3. This dynamic reconfiguration allows the circuit to optimize between signal stability and transmission speed based on operational requirements.
2Power
If transmission gate size is increased to handle large driver output, then signal driving capability is improved, but loading increases due to increased junction capacitance
Solution Approach 1:
The patent extracts transmission gate T1 from the active signal path during bypass operation. This removal eliminates the junction capacitance of T1 from the critical signal path, reducing the total loading effect. The bypass signal enables the circuit to use a smaller effective transmission gate (T4) only when needed, avoiding the continuous penalty of large gate capacitance.
Solution Approach 2:
The patent applies different transmission gate configurations to different operational conditions: full-size transmission gates (T1, T2) for normal operation where stability is paramount, and reduced-size transmission gate (T4) for bypass operation where speed is critical. This local optimization allows each part of the circuit to be sized appropriately for its specific function and operational context.
Data Source
AI summary
Signal delivery delay margin of a bypass flip-flop circuit is stabilized during high-frequency operation. An input controller for logically operating a bypass signal and a clock produces first and second output signals having different states depending on whether or not the bypass signal is activated. A latch circuit latches input data based on the first and second output signals. A latch controller logically operates the bypass signal and input data to generate a third output signal having a different state depending on whether or not the bypass signal is activated. An output controller is switched in response to the states of the first and second output signals for logically combining an output signal selected from the latch circuit and the third output signal to provide the output signal.