Delay-Circuit Flip-Flop for Higher Clock Frequency
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Solution Overview
Problem
The increasing number of flip flops in semiconductor integrated circuits poses challenges in achieving high-speed data storage and transfer, particularly in maintaining data integrity and increasing clock signal frequency due to limitations in existing latch circuits.
Innovation Solution
A high-speed flip flop circuit design incorporating a delay circuit that generates internal signals to latch data signals, allowing for improved data transfer and reduced setup time, thereby enhancing clock signal frequency without the need for separate clock inverters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional latch circuit is used, then the circuit structure is simple, but the clock signal frequency is limited and setup time is large
Solution Approach 1:
The latch circuit is divided into two separate latches (first latch and second latch) operating on different clock phases. The first latch latches data on the rising edge of the clock signal, while the second latch latches the internal output signal on the falling edge. This segmentation allows overlapping operation of the two latches, effectively doubling the data transfer rate and enabling higher clock frequencies without significantly increasing overall circuit complexity.
Solution Approach 2:
The circuit employs periodic clock signal edges (rising and falling edges) to control the two latches alternately. By utilizing both edges of the clock signal for data latching, the circuit achieves higher effective data transfer frequency. The periodic alternating operation of the two latches synchronized with clock edges enables high-speed operation while maintaining a relatively simple circuit structure.
2Speed
If separate clock inverters are added to increase clock frequency, then the clock signal frequency increases, but the power consumption increases
Solution Approach 1:
The clock signal and its inverted version are shared between multiple functions within the circuit. The same clock signal controls both the first latch (on rising edge) and the second latch (on falling edge), eliminating the need for separate clock inverters for each latch. This multi-functional use of the clock signal reduces the number of inverter circuits required, thereby reducing power consumption while maintaining high clock frequency operation.
3Productivity
If the setup time is reduced to increase data transfer speed, then the data transfer speed increases, but the data integrity may be compromised
Solution Approach 1:
The first latch performs preliminary latching of the data signal on the rising edge of the clock signal, creating an internal output signal. This preliminary action prepares the data in advance for the second latch, which then latches this pre-prepared signal on the falling edge. This two-stage preliminary action approach allows reduced setup time while maintaining data integrity, as each latch has sufficient time to stabilize its latched value before the next latching operation.
Solution Approach 2:
The internal output signal from the first latch serves as an intermediary between the original data signal and the final output. This intermediary signal allows the second latch to operate with reduced setup time requirements, as it latches a already-stabilized signal rather than requiring direct latching of the original data signal. The intermediary approach maintains data integrity while enabling higher data transfer speeds.
Data Source
AI summary
A flip flop includes a master latch and a slave latch. The master latch includes a delay circuit configured to receive a clock signal and generate a first internal signal, and is configured to generate an internal output signal by latching a data signal based on the first internal signal. The slave latch is configured to generate a final signal by latching the internal output signal. The delay circuit is further configured to generate the first internal signal by delaying the clock signal by a delay time when the clock signal has a first logic level and generate the first internal signal based on the data signal when the clock signal has a second logic level.