On-Chip Power-Up Reset Circuit Using Ring Oscillator Delay
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Solution Overview
Problem
Existing power-up control solutions for integrated circuits, such as those using external R-C components, are inefficient due to the need for additional pins and large silicon area, as they struggle to ensure sequential digital circuits are reset to a known state during power supply ramping.
Innovation Solution
An on-chip power-up control circuit comprising a voltage detect circuit, delay circuit, and counter circuit that generates a reset signal based on a specified count value, using an on-chip ring oscillator and edge detection to guarantee a predictable reset and clean startup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external R-C components are used to provide delay for reset signal, then the sequential digital circuits can be reset to a known state, but additional dedicated pins are required and device complexity increases
Solution Approach 1:
The patent extracts the delay function from external R-C components and implements it using an on-chip ring oscillator circuit. The ring oscillator generates clock signals that are counted by a counter circuit to produce the delayed reset signal, eliminating the need for external components and dedicated pins while maintaining reliable reset functionality.
Solution Approach 2:
The patent introduces a counter circuit as an intermediary between the ring oscillator and the reset logic. The counter counts clock cycles from the ring oscillator and generates the reset signal after a predetermined number of cycles, serving as a mediator that converts the oscillator's continuous clock signal into a controlled delayed reset pulse without requiring external components.
2Duration of action of moving object
If external R-C components are used to provide delay, then sufficient delay time can be achieved, but the solution requires additional dedicated pins
Solution Approach 1:
The patent merges the delay generation function with the existing on-chip ring oscillator and counter circuits. Instead of using separate external R-C components, the delay is generated by counting clock cycles from the ring oscillator through the counter circuit, integrating multiple functions (oscillation, counting, and delay generation) into a unified on-chip system that eliminates additional pins.
3Device complexity
If on-chip R-C based delay circuit is used, then additional pins are not required, but large silicon area is needed due to slow power supply ramp
Solution Approach 1:
The patent replaces the mechanical/electrical R-C delay mechanism with a digital counting mechanism. Instead of relying on the physical charging time of a capacitor through a resistor (which requires large area for slow power ramps), the system uses a ring oscillator to generate clock signals that are counted by a digital counter to produce the delayed reset signal, significantly reducing the required silicon area.
4Duration of action of moving object
If external R-C components are used, then delay can be provided, but manufacturing cost and device complexity increase
Solution Approach 1:
The patent implements a self-service solution where the power-up control circuit uses its own on-chip ring oscillator and counter circuits to generate the required delay, rather than relying on external R-C components. The ring oscillator automatically generates clock signals upon power-up, and the counter automatically counts these signals to produce the delayed reset signal, making the system self-sufficient and eliminating additional manufacturing steps for external component integration.
Data Source
AI summary
A power-up control circuit utilizes on-chip circuits, multiple voltages, a ring oscillator and counter, and edge and level detection circuits to guarantee reset during power-up conditions and continues the reset state with a variable length counter to guarantee a predictable reset. In addition, a clean start-up after a logical power-down condition is provided.