Master-Slave Flip-Flop Layout for Low-Power High-Speed Clocking
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Solution Overview
Problem
Semiconductor devices face challenges in achieving a balance between low-power consumption and high-speed operation, particularly in flip flop circuits, due to capacitance differences affecting power consumption and operational speed.
Innovation Solution
A master-slave flip flop design with a master latch and slave latch layout that minimizes capacitance differences by using a single clock inverter and optimizing gate line lengths to compensate for capacitance variations, allowing for low-power consumption and high-speed operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional flip flop circuits are designed with separate clock signal paths for master and slave latches, then operational speed can be maintained, but power consumption increases due to capacitance differences
Solution Approach 1:
The patent merges the clock signal distribution by using a single shared clock signal line for both master and slave latches, eliminating separate clock paths. This reduces the total capacitance that needs to be charged and discharged, thereby reducing power consumption while maintaining synchronized operation through the clock enable signals
Solution Approach 2:
The patent changes the operational parameters by introducing clock enable signals (CKE0, CKE1) that control the timing of clock signal acceptance by master and slave latches. This allows asynchronous data capture while sharing the same clock infrastructure, reducing capacitance-related power consumption without sacrificing operational speed
2Device complexity
If gate line lengths are increased to cover more transistors, then device complexity is reduced, but capacitance differences increase affecting power consumption and speed
Solution Approach 1:
The patent segments the clock signal distribution into multiple controlled paths using clock enable signals. Instead of using a single long gate line that would create high capacitance, the clock signal is distributed to master and slave latches separately through enabled control paths, reducing the effective capacitance each clock line must drive while maintaining coordination
3Use of energy by moving object
If gate line lengths are optimized to reduce capacitance, then power consumption decreases, but layout area increases
Solution Approach 1:
The patent resolves the area-capacitance tradeoff by transitioning to a different dimensional approach in signal distribution. Instead of extending gate lines across the layout (increasing area and capacitance), the design uses vertical stacking of latches with localized clock enable signals, reducing the horizontal span of gate lines while maintaining functional coordination through the clock enable mechanism
Data Source
AI summary
A master-slave flip flop includes a master latch and a slave latch which are sequentially disposed on a substrate in a first direction. The master latch includes a first NMOS transistor and a first PMOS transistor each gated by a first clock signal. The first NMOS transistor and the first PMOS transistor share a first gate line extending in a second direction intersecting with the first direction. The slave latch includes a second NMOS transistor and a second PMOS transistor each gated by the first clock signal. The second NMOS transistor and the second NMOS transistor share a second gate line extending in the second direction. The first gate line and the second gate line are electrically connected to each other.