Flip-Flop Clocking Scheme for Balanced Clock-to-Q Delay
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Solution Overview
Problem
Modern flip-flop circuits exhibit a significant variation in clock-to-Q delay between rising and falling edges, leading to an unbalanced duty cycle, which affects downstream circuits and creates issues in clock divider applications.
Innovation Solution
A flip-flop circuit design featuring a primary latch coupled with upper and lower secondary latches in parallel, where clock signals are delayed and inverted to balance the clock-to-Q delay for both edges, achieved through an inverter chain and specific transistor configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a typical flip-flop circuit is used, then the circuit is simple and commonly implemented, but the clock-to-Q delay varies significantly between rising and falling edges, resulting in unbalanced duty cycle
Solution Approach 1:
The flip-flop circuit is segmented into multiple functional blocks: a primary latch, an upper secondary latch, and a lower secondary latch. Each latch is responsible for specific clock edge operations (rising or falling), allowing independent optimization of delay characteristics for each edge type, thereby achieving balanced clock-to-Q delay and 50% duty cycle output.
Solution Approach 2:
Different latch configurations and clock signal treatments are applied locally to specific parts of the circuit. The upper secondary latch receives one clock phase while the lower secondary latch receives another, with each having tailored transistor arrangements and inverter chains to compensate for process variations and achieve uniform delay characteristics across different clock edges.
2Use of energy by moving object
If voltage is decreased to reduce power consumption, then power usage is reduced, but the difference between clock-to-Q delay rise and fall increases, making the flip-flop more unbalanced
Solution Approach 1:
The circuit performs preliminary balancing of the clock-to-Q delay through dedicated inverter chains and transistor sizing adjustments before the actual data output is generated. By pre-compensating for the delay imbalance at lower voltages through the upper and lower secondary latches' differentiated clocking, the circuit maintains balanced output edges even when power consumption is reduced.
Data Source
AI summary
Systems, apparatuses, and methods for implementing low-power flip-flops with balanced clock-to-Q delay are described. A flip-flop includes a primary latch, an upper secondary latch, and a lower secondary latch. The primary latch transmits a data value from an input port to a first node when transparent. The upper secondary latch pulls up a second node when transparent and when the first node is equal to a first value. The second node is a prebuffered data output of the flip-flop. The lower secondary latch pulls down the second node when transparent and when the first node is equal to a second value different from the first value. To ensure the flip-flop has a balanced clock-to-Q delay, a first set of clock signals coupled to transistor gates of the primary latch are delayed with respect to a second set of clock signals coupled to transistor gates of the upper secondary latch.