Pulse-Based Scan Flip-Flop for Lower Setup Time and Delay
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Solution Overview
Problem
Conventional flip-flops with scan inputs have increased setup time and long input-to-output delays due to the inclusion of a multiplexer and the master slave method, making them unsuitable for high-speed applications.
Innovation Solution
A flip-flop design that includes independent first and second pulse signal generators, a signal transmitter, and a signal latch unit, which use pulse signals to transmit and latch data signals, reducing the load at the input terminals and eliminating the need for a multiplexer, thereby minimizing setup time and input-to-output delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multiplexer is included at the input terminal to enable scan input functionality, then the flip-flop can receive both data and scan signals, but the setup time remarkably increases
Solution Approach 1:
The invention segments the signal transmission path by using separate pulse signals for data mode and scan mode. The first pulse signal controls data transmission while the second pulse signal controls scan signal transmission, eliminating the need for a multiplexer and reducing setup time requirements
Solution Approach 2:
The invention introduces pulse signals as intermediary control elements that mediate between the mode selection (data/scan) and the actual signal transmission. These pulse signals act as temporary carriers that enable mode-specific transmission without requiring a complex multiplexer structure
2Reliability
If a master slave flip-flop structure is used, then the flip-flop can store and transmit data sequentially, but the input-to-output delay becomes long
Solution Approach 1:
The invention uses periodic pulse signals to control the transmission and latching operations. The first pulse signal triggers the signal transmitter, and the second pulse signal triggers the signal latch unit, creating a streamlined periodic operation that reduces delay compared to the continuous master-slave cycle
Solution Approach 2:
The invention extracts and eliminates the intermediate master stage from the traditional master-slave flip-flop structure. By directly connecting the pulse-controlled transmitter to the latch unit, it removes the redundant delay stage while maintaining the sequential storage and transmission functionality
3Adaptability or versatility
If a multiplexer is used to select between data and scan inputs, then both modes can be supported, but the load at input terminals increases
Solution Approach 1:
The invention dynamically configures the signal transmission path based on the operating mode. When in data mode, the first pulse signal activates the data transmission path; when in scan mode, the second pulse signal activates the scan signal path. This dynamic switching eliminates the need for a static multiplexer structure and reduces input terminal load
Data Source
AI summary
A flip-flop for transmitting a scan input and data for scan-testing a semiconductor circuit is provided. The flip-flop includes a first pulse signal generator which generates a first pulse signal in response to a scan enable signal and an inversed scan input signal. A second pulse signal generator generates a second pulse signal in response to the scan enable signal and a scan input signal. A signal transmitter receives a data signal and transmits the data signal to a first node in response to either one of the first and second pulse signals. A signal latch unit receives the data signal transmitted to the first node, and latches and outputs the data signal in response to another one of the first and second pulse signals.