OTP Memory Read Circuit Using Schmitt Trigger for Noise Immunity
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Solution Overview
Problem
Existing circuits for reading One Time Programmable (OTP) memory face challenges in accurately detecting the programmed state due to fluctuations in voltage and resistance errors caused by temperature and noise, leading to potential misinterpretation and increased power consumption for amplification, which affects reliability and efficiency.
Innovation Solution
A circuit that includes a controller generating read delay and latch signals, a read voltage generator, and detecting units with Schmitt trigger circuits and transfer gates to stabilize voltage detection and reduce noise sensitivity, eliminating the need for additional amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a buffer or differential amplifier is used to improve the detecting rate, then the detecting rate is improved, but the power consumption increases and additional circuit space is required
Solution Approach 1:
The patent extracts and eliminates the amplifier component from the reading circuit, achieving the detecting function through the Schmitt trigger circuit's inherent voltage threshold comparison capability. This removes the source of additional power consumption while maintaining detection accuracy through the Schmitt trigger's built-in hysteresis mechanism.
Solution Approach 2:
The Schmitt trigger circuit performs self-amplification of the voltage signal through its inherent positive feedback mechanism, eliminating the need for external amplifiers. The circuit automatically provides the necessary gain and hysteresis for reliable detection without requiring additional active components that would increase power consumption.
2Measurement precision
If the voltage of the detecting node is allowed to fluctuate to improve detection, then the detecting rate improves, but the buffer or differential amplifier may output a wrong signal due to noise
Solution Approach 1:
The Schmitt trigger circuit employs positive feedback through its hysteresis mechanism, where the output signal feeds back to the input through a resistor network. This feedback establishes stable voltage thresholds that prevent false triggering due to noise, while still allowing the node voltage to fluctuate within controlled ranges for accurate detection.
Solution Approach 2:
The Schmitt trigger circuit provides beforehand cushioning against noise through its hysteresis voltage margins. The upper and lower threshold voltages create a noise immunity buffer that prevents spurious transitions, protecting the detection accuracy before noise can cause false signals.
3Measurement precision
If testing is performed at stable voltage and room temperature, then the test result is obtained, but the OTP memory may operate abnormally in real-life environment due to temperature and process variations
Solution Approach 1:
The patent employs parameter changes by using the Schmitt trigger circuit's voltage threshold characteristics that are inherently robust to temperature and process variations. The hysteresis mechanism provides a margin that accommodates parameter drift, allowing the circuit to maintain reliable operation across different environmental conditions without requiring separate testing protocols.
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 proposed circuit improves detection accuracy and reliability by stabilizing voltage readings and reducing noise impact, while also minimizing power consumption and circuit complexity.
Implementation Method 1
a first detecting unit that determines a voltage at the detecting node
Implementation Method 2
The programming operation of an anti-fuse involves applying a high voltage that is higher than a break-down voltage, thereby destroying the gate oxide layer
Implementation Method 3
when the anti-fuse is electrically short, the voltage at the detecting node is determined based on a resistance ratio of a read voltage generator and the anti-fuse that are connected in series
Data Source
AI summary
A circuit for reading a one time programmable (OTP) memory includes a controller that receives a read input signal and generates a read delay signal, a read voltage signal, and a read latch signal; a read voltage generator that generates a read voltage based on the read voltage signal and outputs the read voltage to a detecting node; an OTP memory unit cell including a first electrode connected to the detecting node; a first detecting unit that determines a voltage at the detecting node; a determining unit that delays an output signal from the first detecting unit based on the read delay signal; and a latch unit that latches an output signal from the determining unit during a first delay time at a falling edge of the read input signal based on the read latch signal.