Word Line Driver Control Switch for ESD Protection
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Solution Overview
Problem
Existing word line drivers are susceptible to errors due to electrostatic discharge (ESD) and erroneous programming during power on operations, as the gate of the first transistor is coupled to the operating voltage, leading to incorrect generation of the word line signal and subsequent programming of memory cells.
Innovation Solution
A word line driver configuration that includes a control switch and a cross-coupled amplifier, with a control signal managing the connection between a first and second node, allowing the word line driver to maintain the voltage level at the second node sufficient to keep the first transistor in an 'off' state during ESD events and ensuring accurate programming by decoupling the voltage levels during power on operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gate of the first transistor is coupled to the operating voltage, then the word line driver can generate the word line signal, but the word line signal becomes susceptible to errors due to electrostatic discharge (ESD)
Solution Approach 1:
A control switch is introduced as an intermediary component between the operating voltage source and the gate of the first transistor. This control switch mediates the connection by selectively coupling or decoupling the operating voltage to the transistor gate based on system state, thereby preventing direct exposure to ESD events while maintaining normal operation when needed.
Solution Approach 2:
The control switch is activated in advance to decouple the gate of the first transistor from the operating voltage during conditions when ESD protection is needed (such as during power-on or when ESD events are detected). This preliminary protective action prevents the harmful ESD effect from reaching the transistor gate before damage can occur.
2Productivity
If the first operating voltage is connected to the gate of the first transistor and fully powers on before the second operating voltage, then the circuit powers on quickly, but the first transistor erroneously programs the activated portions of the memory array
Solution Approach 1:
The control switch serves as a mediator that manages the power-on sequencing between different voltage domains. It allows the first operating voltage to power on quickly while controlling when it is actually coupled to the transistor gate, ensuring that coupling only occurs after the second operating voltage is stable, thus preventing erroneous programming during power-on transitions.
Solution Approach 2:
The control switch is activated in advance to prevent coupling of the first operating voltage to the transistor gate during the power-on sequence. This preliminary protective measure ensures that even if the first voltage powers on before the second voltage, the transistor remains isolated and cannot cause erroneous programming until proper sequencing is established.
Data Source
AI summary
A word line driver including a control switch configured to receive a control signal, where the control switch is between a first node configured to receive an operating voltage signal and a second node configured to determine an output of the word line driver. The word line driver further includes a cross-coupled amplifier electrically connected to the second node. The word line driver further includes at least one inverter electrically connected to the cross-coupled amplifier. A semiconductor device including the word line driver and a memory array including at least one electronic fuse.