Semiconductor Voltage Initialization Circuit Preventing Latch-Up
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Solution Overview
Problem
Conventional semiconductor devices experience latch-up phenomena and inadequate initialization of internal circuits due to insufficient boosting voltage before power up, especially when the power supply voltage is reduced, leading to potential damage.
Innovation Solution
A semiconductor device with a boosting voltage generation circuit that maintains a voltage level higher than the power supply voltage before power up by comparing divided voltage nodes and activating an enable signal to increase the boosting voltage, ensuring a stable voltage difference and preventing excessive current usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the power supply voltage VDD is reduced to improve power efficiency, then power consumption is reduced, but the boosting voltage VPP becomes insufficient before power up causing latch-up phenomena
Solution Approach 1:
The patent applies preliminary action by initializing the internal voltage to a desired voltage level before the power up operation completes. The voltage initialization circuit pre-charges the boosting voltage node to ensure that when the cell transistor needs to turn on during precharge operations, sufficient voltage difference exists between the word line and bit line even before VDD reaches its final level, thereby preventing latch-up phenomena
Solution Approach 2:
The patent changes the voltage parameter dynamically by using different initialization strategies based on the power up stage. The voltage initialization circuit adjusts the boosting voltage level relative to the power supply voltage during the power up transition, ensuring that the voltage difference required for proper transistor operation is maintained throughout the transition period
2Reliability
If the boosting voltage VPP is increased before power up to prevent latch-up, then reliability is improved, but excessive current is consumed
Solution Approach 1:
The patent applies partial action by providing just enough boosting voltage to initialize internal circuits to a safe state before power up, rather than maintaining full operating voltage levels throughout the entire power up sequence. The voltage initialization circuit provides partial pre-charging that is sufficient to prevent latch-up but limited enough to avoid excessive current consumption
Solution Approach 2:
The patent uses periodic action through the power up control signal that enables the voltage initialization circuit only during the power up transition period. The initialization occurs in a time-limited window before and during power up, then stops once normal operation begins, preventing continuous current consumption while still providing protection during the critical transition phase
3Productivity
If the cell transistor TR is turned on before power up using boosting voltage VPP, then internal circuit initialization is achieved, but the transistor may not turn on sufficiently due to insufficient voltage difference
Solution Approach 1:
The patent introduces an intermediary mechanism - the voltage initialization circuit that acts as a mediator between the power supply voltage and the boosting voltage. This intermediary circuit ensures that the boosting voltage node is pre-charged to an appropriate level relative to the power supply voltage, creating the necessary voltage difference for reliable transistor switching during the power up transition without requiring the transistor to switch prematurely
Data Source
AI summary
A semiconductor device includes: a unit configured to, in a period before power up, compare a voltage obtained by dividing a voltage of a first voltage node at a first division ratio with a voltage obtained by dividing a voltage of a second voltage node at a second division ratio and determine whether to activate an enable signal according to a result of the comparison; and a voltage driving unit configured to increase the voltage of the second voltage node when the enable signal is activated in the period before power up.