Bitline Sensing Latch Using Cross-Coupled Transistors
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Solution Overview
Problem
Existing register file circuits require a dynamic sense amplifier and a separate latch circuit for bit line sensing, which increases area consumption and complexity.
Innovation Solution
A bit line sensing latch circuit is implemented without a sense amplifier, using a single pair of cross-coupled transistors as a keeper and a precharge circuit that operates in two phases, allowing for bit line sensing and storage with a single control signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dynamic sense amplifier and a separate latch circuit are used for bit line sensing, then sensing accuracy and reliability are improved, but area consumption and device complexity increase
Solution Approach 1:
The patent combines the sense amplifier and latch circuit into a single integrated bit line sensing latch. The cross-coupled transistor structure performs both sensing and latching functions simultaneously, eliminating the need for separate sense amplifier and latch circuits while maintaining sensing accuracy and reliability.
Solution Approach 2:
The cross-coupled transistor structure serves multiple functions: it acts as a sense amplifier to detect bit line voltage differences, a latch to store the sensed value, and a precharge circuit to reset the differential nodes. This multi-functionality reduces overall circuit complexity while maintaining sensing reliability.
2Reliability
If a dynamic sense amplifier and separate latch circuit are used, then sensing function is improved, but area consumption increases
Solution Approach 1:
By merging the sense amplifier and latch circuit into a single bit line sensing latch with cross-coupled transistors, the patent significantly reduces the area required for bit line sensing while maintaining full sensing functionality. The integrated structure eliminates redundant circuit elements and interconnections.
Solution Approach 2:
The cross-coupled transistor structure performs multiple functions (sensing, latching, precharging) within a compact area, eliminating the need for separate dedicated circuits for each function and thereby reducing total area consumption.
3Area of stationary object
If a single pair of cross-coupled transistors is used as keeper, then area consumption is reduced, but sensing and storing capability must be maintained
Solution Approach 1:
The single pair of cross-coupled transistors is designed to perform multiple functions simultaneously: acting as a keeper to maintain latch state, functioning as a sense amplifier to detect differential voltages, and serving as a precharge circuit. This multi-functionality ensures sensing and storing capabilities are maintained despite reduced area.
Solution Approach 2:
The patent optimizes the transistor dimensions, threshold voltages, and operating conditions of the cross-coupled pair to ensure that the reduced structure maintains adequate sensing margin and storage stability. Parameter optimization compensates for the reduced device count while maintaining reliability.
Data Source
AI summary
A bit line sensing latch circuit is disclosed. In one embodiment, a latch circuit includes a keeper and a precharge circuit. The keeper may be implemented using a single pair of transistors that are cross-coupled between first and second differential signal nodes. A gate terminal of a first one of the pair of transistors is coupled to the first differential signal node, while the drain terminal of the same transistor is coupled to the second differential signal node. The gate terminal of a second one of the pair of transistors is coupled to the second differential signal node, while its drain terminal is coupled to the first differential signal node. The bitline sensing latch also includes a precharge circuit, and may operates in two phases, a precharge phase and an enable phase.