Master-Slave Flip-Flop With Tristate Drive for Lower Clock Delay
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Solution Overview
Problem
Conventional master-slave flip-flop architectures face challenges in minimizing setup time and clock output delay, which impact their speed and performance, particularly due to the need for buffer circuits that introduce additional delay and reduce drive strength during signal transitions.
Innovation Solution
The proposed master-slave flip-flop design incorporates a tristate driver with pm and nm transistors that prevent the common node from being pulled high or low, eliminating the need for a buffer and allowing the tristate driver to maintain high drive strength during clock transitions, thereby reducing delays and improving response time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a buffer circuit is used in conventional master-slave flip-flop architectures, then signal stability is improved, but clock output delay increases and drive strength decreases
Solution Approach 1:
The patent removes the buffer circuit from the master-slave flip-flop architecture. The tristate driver directly drives the common node without requiring a buffer, thereby eliminating the delay and drive strength degradation introduced by the buffer while maintaining signal stability through the tristate control mechanism.
Solution Approach 2:
The patent implements dynamic control of the tristate driver using clock-dependent pm and nm signals. These signals dynamically enable or disable the tristate driver's pull-up and pull-down capabilities based on the clock phase, allowing the circuit to adapt its driving strength in real-time without requiring a static buffer.
2Stability of the object's composition
If a buffer circuit is used in conventional master-slave flip-flop architectures, then signal stability is improved, but drive strength during signal transitions decreases
Solution Approach 1:
The patent removes the buffer circuit that was degrading drive strength. The tristate driver now directly controls the common node, restoring full drive strength during signal transitions while maintaining stability through the clock-synchronized pm and nm control signals that prevent conflicting pull-up and pull-down operations.
Solution Approach 2:
The patent uses dynamic tristate control where the pm and nm signals are generated based on clock phase and common node state. This dynamic control allows the tristate driver to provide maximum drive strength when needed while maintaining stability through coordinated enablement of pull-up and pull-down paths, eliminating the drive strength degradation caused by buffer circuits.
3Speed
If additional circuitry is added to prevent unnecessary changes to the common node, then speed is improved, but device complexity increases
Solution Approach 1:
The patent merges the tristate driver control logic directly into the master latch structure. The pm and nm control signals are generated within the master latch using the existing clock input and common node feedback, eliminating the need for separate control circuits while preventing unnecessary common node changes and improving speed.
Solution Approach 2:
The master latch structure serves multiple functions: it samples the data input, generates the tristate control signals (pm and nm), and directly controls the tristate driver. This multi-functionality eliminates the need for additional dedicated control circuitry, maintaining simplicity while achieving fast signal propagation by preventing unnecessary common node transitions.
Data Source
AI summary
A master-slave flip-flop includes a first latch, a second latch and a tristate driver. The first latch has a combined input/output that is coupled with a common node, a pm output, and an nm output. The tristate driver has pm and nm inputs coupled with the pm and nm outputs of the first latch, and a tristate output coupled with the common node. A pm input signal prevents the tristate driver from pulling the common node high, and an nm input signal prevents the tristate driver from pulling the common node low. The second latch is directly coupled with the common node. The first latch generates an nm signal and a pm signal in response to a signal on the first latch clk input and a state of the common node, wherein the pm signal and the nm signal have opposite polarities when the signal on the first latch clk input has a first value, and equal polarities when the signal on the first latch clk input has a second value.