Level-Shifter D Flip-Flop for High-Swing Output Signals
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Solution Overview
Problem
Conventional D flip-flops face limitations in efficiently handling multiple inputs and generating high-swing output signals, which restricts their application in integrated circuits where high-swing signals are required, such as in Dynamic Pattern Generators.
Innovation Solution
The proposed D flip-flop incorporates a level shifter that receives small-swing input signals and generates high-swing output signals by using a combination of NMOS and PMOS transistors, along with a duty-cycle control voltage to adjust the duty cycle of the output signals, allowing for improved output swing from 1.2V to 2.5V.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional D flip-flop structure is used, then device complexity is low, but output swing is limited to small voltage range
Solution Approach 1:
The D flip-flop is divided into multiple functional blocks: a first D flip-flop for capturing input data, a level shifter for voltage conversion, and a second D flip-flop for outputting high-swing signals. This segmentation allows each block to perform its specific function optimally, with the level shifter specifically designed to expand the output voltage swing from small-signal range to large-signal range (e.g., from 1.2V to 2.5V), thereby resolving the contradiction between maintaining simple structure and achieving high output swing.
Solution Approach 2:
A level shifter circuit is introduced as an intermediary component between the input D flip-flop and the output stage. This level shifter acts as a mediator that converts small-swing signals from the first D flip-flop into high-swing signals for the second D flip-flop, enabling the system to achieve large output voltage swing without requiring the entire flip-flop structure to be complex. The level shifter specifically transforms the voltage amplitude while maintaining the logical functionality.
2Adaptability or versatility
If level shifter is added to generate high-swing output, then output swing increases, but device complexity increases
Solution Approach 1:
The level shifter circuit is designed to perform multiple functions: it converts voltage levels, adjusts duty cycle of output signals, and interfaces between different flip-flop stages. By making the level shifter multi-functional, the patent reduces the need for additional separate components, thereby achieving high output swing without proportionally increasing overall device complexity. The same level shifter structure handles both voltage conversion and duty cycle adjustment.
Solution Approach 2:
The level shifter dynamically changes output signal parameters (voltage level and duty cycle) based on control signals. By varying the duty cycle control voltage, the circuit can adjust the output signal characteristics to match different application requirements. This parameter flexibility allows a single circuit configuration to achieve high output swing across multiple operating conditions, reducing the need for multiple specialized circuits.
3Adaptability or versatility
If multiple inputs are handled, then functionality improves, but difficulty in generating high-swing output increases
Solution Approach 1:
The patent segments the multi-input handling function across multiple D flip-flop stages, with each flip-flop capturing data from different inputs at different clock edges. The level shifter then processes the combined output to generate the final high-swing signal. This segmentation allows the circuit to handle multiple inputs systematically without overwhelming the output generation stage, as each input is processed sequentially through the segmented architecture.
Data Source
AI summary
A D flip-flop includes a first switch, a level shifter, and a second switch therein. The first switch includes a first input and a first output. The level shifter includes a second input coupled to the first input, and a second output. The second switch includes a third input coupled to the second output, and a third output. The first input and the third output form an input and an output of the D flip-flop.