Latching Current Sensing Amplifier for Memory Arrays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional techniques fail to accurately sense a 10-mV Vt difference in programmable read-only memory arrays without adjusting the wordline level, which is unpredictable across varying process, voltage, and temperature conditions.
Innovation Solution
A latching current sensing amplifier circuit with series-connected p-type transistors and a cross-coupled configuration for both sensing and latching operations, injecting and drawing currents from bitlines to provide gain and voltage output, and reconfiguring into a cross-coupled latch for digital output, controlled by a single digital input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a voltage sense system is used to sense a 10-mV Vt difference, then sensing capability is improved, but the wordline level must be precisely adjusted which is not predictable across PVT variations
Solution Approach 1:
The patent replaces the voltage-based sensing mechanism with a current-based sensing mechanism. Instead of adjusting wordline voltage to achieve proper sensing, the system uses current sense amplifiers that automatically sense the 10-mV Vt difference through current flow in differential bitlines, eliminating the need for precise voltage control and adjustment.
Solution Approach 2:
The patent changes the sensing parameter from voltage to current. By using current sense amplifiers that operate with self-biased current sources, the system transforms the sensing problem from voltage-dependent to current-dependent, making it independent of wordline voltage level and thus immune to PVT variations.
2Measurement precision
If current sense amplifiers with self-bias are used, then sensing accuracy is improved across PVT variations, but circuit complexity increases
Solution Approach 1:
The patent implements multi-functionality by using the same current sense amplifier circuit for both sensing and latching operations. The amplifier can operate in sensing mode with self-biased current sources for accurate measurement, and transition to latching mode using cross-coupled transistors for digital output, eliminating the need for separate sensing and latching circuits.
Solution Approach 2:
The patent introduces dynamic reconfiguration capability where the circuit topology changes based on operational mode. The current sense amplifier can dynamically switch between sensing configuration (with self-bias) and latching configuration (with cross-coupled transistors), allowing a single circuit to perform multiple functions adaptively.
3Adaptability or versatility
If the sensing amplifier operates over extended common-mode cell currents, then adaptability is improved, but signal integrity may deteriorate
Solution Approach 1:
The patent employs self-biased current sources that automatically adjust their operation based on the common-mode current level. The feedback mechanism in the current sense amplifier maintains proper sensing operation across extended common-mode currents by dynamically compensating for variations, ensuring signal integrity is preserved throughout the operating range.
Data Source
AI summary
A latching current sensing amplifier circuit for memory arrays and a current sensing technique using the latching current sensing amplifier circuit are provided. The current sense-amplifier circuit includes a first and second pair of series connected transistors configured with a common gate node for a sense operation and reconfigurable as a cross-coupled pair for a latching operation.