Dynamic Cross-Coupled Sense Amplifier for Faster Bit Decisions
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Solution Overview
Problem
High-speed sense amplifiers face reduced sensitivity and slower bit decision speeds due to the IR voltage drop across the third regeneration-stage switch, which affects the regenerative gain and efficiency of the cross-coupled inverters in the regeneration stage.
Innovation Solution
A regeneration stage with clock-driven inverters dynamically controls the cross-coupling of the inverters, eliminating the need for the third regeneration-stage switch, allowing direct coupling to the supply rail, thereby increasing regenerative gain and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a third regeneration-stage switch is used to control cross-coupling, then the circuit can be controlled, but IR voltage drop reduces sensitivity and slows bit decision speed
Solution Approach 1:
The patent removes the third regeneration-stage switch from the circuit topology. By eliminating this switch, the IR voltage drop problem is eliminated, allowing the cross-coupled inverters to operate with full regenerative gain without the performance degradation caused by the switch's on-resistance.
Solution Approach 2:
Instead of using a switch to enable/disable cross-coupling, the patent inverts the approach by using the natural state of the cross-coupled inverters to provide regenerative gain, with reset switches temporarily breaking the cross-coupling during reset phase rather than using a third switch to control it during operation.
2Measurement precision
If cross-coupled inverters are used for regenerative gain, then sensitivity is improved, but IR voltage drop across the switch reduces the gain and slows decision rendering
Solution Approach 1:
The patent extracts and removes the third regeneration-stage switch that was causing the IR voltage drop. This elimination allows the cross-coupled inverters to maintain full regenerative gain, improving both the sensitivity of signal detection and the speed of decision rendering by removing the time-consuming voltage drop effect.
Data Source
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AI summary
In certain aspects, a regenerative stage of a sense amplifier includes a first inverter having an input and an output, and a second inverter having an input and an output. The regenerative stage also includes a third inverter having an input, an output coupled to the input of the second inverter, a first supply terminal coupled to a supply rail, and a second supply terminal coupled to the output of the first inverter. The regenerative stage further includes a fourth inverter having an input, an output coupled to the input of the first inverter, a first supply terminal coupled to the supply rail, and a second supply terminal coupled to the output of the second inverter.