Time-Based OTP Memory Sensing Circuit for Low Power Read Operations
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for sensing programmable resistive device memories require high supply voltage and high current, making it difficult to operate under low voltage and low current conditions, which is a challenge in IoT and other low-power applications.
Innovation Solution
A time-based sensing circuit that uses capacitors to determine resistance by charging and discharging them through programmable resistive elements, comparing the discharging time with a reference voltage to convert resistance into logic states, eliminating the need for high MOS device biasing and current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional voltage sense amplifier is used to sense PRE resistance, then measurement precision is improved, but use of energy increases substantially
Solution Approach 1:
The patent replaces the conventional voltage-based sensing mechanism with a time-based sensing mechanism. Instead of using high-voltage MOS amplifiers to convert resistance to voltage and amplify the signal, the invention uses capacitors charged and discharged through the resistive element, measuring the discharge time constant. This time-based approach eliminates the need for high-voltage biasing and substantial current consumption while maintaining measurement capability.
Solution Approach 2:
The patent changes the sensing parameter from voltage (conventional approach) to time (invention approach). By measuring the time constant of capacitor discharge through the resistive element, the system converts resistance measurements into time measurements. This parameter transformation enables operation at low voltage and low current, fundamentally changing how the sensing circuit operates.
2Measurement precision
If high voltage is applied to bias MOS devices in high gain region, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces the complex voltage-based MOS amplifier system with a simpler time-based capacitor discharge system. The new approach uses basic capacitor charging and discharging circuitry instead of complex high-gain MOS amplifiers, reducing circuit complexity while maintaining measurement precision through time constant measurement.
Solution Approach 2:
Instead of converting resistance to voltage and amplifying the voltage signal (conventional approach), the invention converts resistance to a time constant and measures the time. This inversion of the sensing approach simplifies the circuit by eliminating the need for high-voltage biasing and complex amplification stages.
3Measurement precision
If high current is used to flow through PRE for sensing, then measurement precision is improved, but loss of energy increases
Solution Approach 1:
The patent changes the measurement parameter from current-based voltage sensing to time-based capacitor discharge measurement. By measuring the time constant during capacitor discharge through the resistive element, the system achieves accurate resistance measurement without requiring high current flow, thereby reducing energy loss.
Solution Approach 2:
The sensing operation is performed periodically by charging and discharging the capacitor through the resistive element. This periodic action allows the system to measure resistance through time constant observation rather than requiring continuous high current flow, reducing overall energy consumption while maintaining measurement precision.
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
Enables low voltage and low current sensing in programmable resistive memory cells, achieving efficient data storage and retrieval while reducing power consumption, suitable for use in various memory types like OTP, MTP, PCRAM, RRAM, and MRAM.
Implementation Method 1
A capacitor can be charged to near a supply voltage level during a first period of time. Then, the capacitor can be discharged through a resistance over a second period of time.
Implementation Method 2
The resistance of a PRE in a PRD device needs to be converted into a logic level after reading the PRD cell.
Data Source
AI summary
A time-based sensing circuit to convert resistance of a one-time programmable (OTP) element into logic states is disclosed. A one-time programmable (OTP) memory has a plurality of OTP devices. At least one of the OTP devices can have at least one OTP element that is selectively accessible via a wordline and a bitline. The bitline can be coupled a capacitor and the capacitor can be precharged and discharged. By comparing the discharge rate of the capacitor to discharge rate of a reference capacitor in a reference unit (e.g., reference cell, reference resistance, reference selector, etc.), the PRE resistance can be determined larger or smaller than a reference resistance and then converting the OTP element resistance into a logic state.