Conditional Boosting Flip-Flop for Low-Voltage Speed Recovery
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Solution Overview
Problem
Excessive voltage scaling in CMOS digital circuits for portable electronics leads to severe speed reduction, and existing capacitive boosting techniques consume significant power due to performing bootstrapping operations for all input transitions.
Innovation Solution
A flip-flop design incorporating a conditional boosting stage with a boosting capacitor that pre-charges and boosts a node only when the previous output signal differs from the current input signal, along with a pulse generator to generate pulsed signals based on clock transitions, and a latch to process the input signal, thereby reducing power consumption and latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If voltage scaling is applied to minimize power consumption, then power consumption is reduced, but speed performance deteriorates
Solution Approach 1:
The patent dynamically changes the gate-source voltage parameter of select transistors using a boosting capacitor. When a transition is detected, the boosting capacitor charges to supply voltage and couples to the gate, temporarily increasing the gate-source voltage above the normal supply voltage. This parameter change enables transistors to operate faster during critical transitions while maintaining low power consumption during steady-state operation at scaled voltages.
2Speed
If capacitive boosting technique is applied to overcome speed reduction, then speed performance is improved, but power consumption increases significantly
Solution Approach 1:
The patent applies capacitive boosting selectively rather than continuously. The boosting capacitor is activated only when a transition is detected at the input or output of the flip-flop, providing excessive voltage temporarily only when needed for speed enhancement. During non-transition periods, the boosting circuit remains inactive, avoiding the continuous power consumption that would otherwise occur with traditional bootstrapping techniques.
Solution Approach 2:
The patent employs transition detection mechanisms that monitor input and output signals to determine when boosting is required. The detection logic provides feedback to the boosting capacitor control, enabling the boosting action only when a transition occurs. This feedback-based control ensures that power is consumed for boosting only when it provides useful speed enhancement, rather than continuously as in traditional approaches.
3Power
If bootstrapping operation is performed for all input transitions, then driving capability is enhanced, but power consumption becomes significant
Solution Approach 1:
The patent performs bootstrapping operation partially rather than for all transitions. The transition detection logic identifies specific conditions (input or output transitions) and activates the boosting capacitor only for those cases. This selective application provides enhanced driving capability when needed while avoiding unnecessary power consumption during transitions that do not require boosting.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The conditional boosting flip-flop reduces power consumption by up to 9% and enhances driving capability, minimizing latency and sensitivity to process errors while maintaining energy efficiency, especially in low-frequency switching operations.
Implementation Method 1
The conditional boosting stage includes a boosting capacitor, and is configured to pre-charge the boosting capacitor in accordance with a previous output signal and boost a node connected to the boosting capacitor upon a level of the previous output signal being different from a level of a current input signal
Data Source
AI summary
A flip-flop includes a conditional boosting stage, a pulse generator and a latch. The conditional boosting stage includes a boosting capacitor, and is configured to pre-charge the boosting capacitor in accordance with a previous output signal and boost a node connected to the boosting capacitor upon a level the previous output signal being different from a level of a current input signal. The pulse generator is configured to generate a pulsed signal in accordance with transitions of a clock signal. The latch configured is to latch the current input signal to a current output signal in accordance with the pulsed signal.