Native NMOS Power-On Reset Circuit for Slow Supply Ramps
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power-on-reset (POR) circuits consume power and occupy significant circuit space, and are not robust enough to handle very slow ramp rates, leading to unpredictable device initial states and potential signal validity issues.
Innovation Solution
A low-power POR circuit utilizing only active devices, specifically native transistors, which generate a reference current independent of supply voltage and compare it with a sense current to determine the supply voltage level, eliminating the need for resistors or capacitors and ensuring robust performance even at slow ramp rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional POR circuits using resistors, capacitors or memory circuits are used, then the circuit can provide power-on reset functionality, but the circuit consumes more power and occupies more area
Solution Approach 1:
The patent replaces conventional passive components (resistors, capacitors) and memory circuits with an active device-based implementation using native transistors. This substitution eliminates the need for external passive components while achieving the same POR functionality with lower power consumption and smaller area, directly addressing the contradiction between power/area efficiency and reliability.
Solution Approach 2:
The patent changes the operational parameters by using native transistors operating in specific regions to generate voltage thresholds through current comparisons. This parameter change enables the circuit to achieve robust slow-ramp-rate performance without requiring large capacitors or complex memory circuits, thereby reducing both power consumption and circuit area while maintaining reliability.
2Area of stationary object
If conventional POR circuits are used, then the circuit can detect supply voltage levels, but the circuit occupies significant circuit space
Solution Approach 1:
The patent substitutes conventional POR circuit implementations that require resistors, capacitors, and memory circuits with a compact active device-based circuit using native transistors. This substitution dramatically reduces the circuit area while maintaining the ability to detect supply voltage levels and provide robust performance at slow ramp rates.
Solution Approach 2:
The native transistor-based circuit performs multiple functions within a single compact structure: it generates voltage thresholds, compares supply voltage levels, and provides reset functionality. This multi-functionality eliminates the need for separate passive components and memory circuits, achieving both area reduction and maintained reliability.
3Productivity
If processing circuits are activated without POR circuit, then the device can start processing faster, but the initial state becomes unpredictable and signals may be invalid
Solution Approach 1:
The POR circuit performs preliminary action by detecting when the supply voltage reaches a valid level before allowing processing circuits to become active. This preliminary voltage level detection ensures that all circuits are properly initialized and signals are valid before processing begins, maintaining predictable initial states while enabling fast startup through efficient active device-based detection.
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 solution provides a compact, power-efficient POR circuit that consumes less than 42 nano-amperes of current on average and is robust across temperature and voltage variations, ensuring predictable device startup and reduced resource constraints.
Implementation Method 1
a first native transistor configured to generate a reference current indicative of a voltage threshold
Implementation Method 2
a comparator transistor having a control node coupled to the native NMOS transistor, the comparator transistor configured to compare a sense current with the reference current
Data Source
AI summary
This application discusses techniques for providing a power-on reset (POR) circuit. The techniques take advantage of the small size of active devices, consume very little current and can use a native NMOS transistor to provide a stable reference over temperature and voltage variations.