Comparator-Based Power-On-Reset for Accurate Multi-Voltage Detection
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Solution Overview
Problem
Conventional power-on-reset circuitry for integrated circuits faces challenges in accurately monitoring multiple power supply voltages, especially as core power supply voltages decrease and transistor sizes shrink, leading to increased susceptibility to process and temperature variations, which degrades accuracy and makes it difficult to produce reliable power-on-reset signals.
Innovation Solution
The implementation of comparator-based trip point detectors, powered by a voltage reference source, which use voltage divider or multiplier circuitry to generate desired voltage trip points and compare them with actual power supply voltages, along with a power-on-reset controller that processes output signals to produce a POR signal, while incorporating feedback and noise filtering to enhance accuracy and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional power supply monitoring circuits are constructed from transistors with known threshold voltages, then a signal can be generated to indicate when a power supply voltage trip point has been exceeded, but the accuracy is degraded due to process and temperature variations affecting the ratio of transistor threshold voltage to core power supply voltage
Solution Approach 1:
The patent changes the monitoring approach from using fixed transistor threshold voltages to using dynamically adjustable trip point voltages generated by voltage reference circuits and divider networks. This allows the trip points to be set at specific voltage levels independent of transistor parameter variations, thereby maintaining monitoring accuracy across different process and temperature conditions.
Solution Approach 2:
The patent introduces voltage reference circuits and voltage divider networks as intermediary components between the power supply voltage and the comparator inputs. These intermediaries generate stable reference voltages that are not directly affected by transistor threshold variations, enabling accurate comparison and detection of power supply voltage trip points despite process and temperature changes.
2Adaptability or versatility
If multiple power supply voltages are monitored using conventional circuits, then power-on-reset signals can be generated for each voltage, but the processing burden increases and accurate monitoring becomes difficult due to different power-up times and operating voltages
Solution Approach 1:
The patent divides the monitoring function into separate comparator circuits, each dedicated to monitoring a specific power supply voltage. Each comparator independently compares its assigned power supply voltage against predefined trip points, eliminating the need for complex centralized processing and reducing the processing burden while maintaining the ability to handle multiple voltages with different characteristics.
Solution Approach 2:
The patent employs a universal comparator-based detection mechanism that can be applied to multiple different power supply voltages. The same comparator circuit architecture, voltage reference generation, and trip point comparison methodology work across all monitored voltages regardless of their specific levels or power-up sequences, providing a scalable and adaptable solution.
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
This solution provides improved accuracy and reliability in generating power-on-reset signals, is insensitive to power-up sequence, and effectively blocks brownout detection during testing, ensuring stable operation across varying power supply conditions.
Implementation Method 1
A voltage reference source such as a bandgap voltage reference may supply a reference voltage to the trip point detectors
Implementation Method 2
A comparator in each trip point detector is used to compare a power supply voltage that has been received by that detector to the voltage trip point for that detector
Implementation Method 3
The trip point detectors contain voltage divider circuitry or voltage multiplier circuitry generating desired voltage trip points from the reference voltage
Data Source
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AI summary
Power-on-reset circuitry is provided for integrated circuits such as programmable logic device integrated circuits. The power-on-reset circuitry may use comparator-based trip point voltage detectors to monitor power supply voltages. The trip point detectors may use circuitry to produce trip point voltages from a bandgap reference voltage. Controller logic may process signals from the trip point detectors to produce a corresponding power-on-reset signal. The power-on-reset circuitry may contain a noise filter that suppresses noise from power supply voltage spikes. Normal operation of the power-on-reset circuitry may be blocked during testing. The power-on-reset circuitry may be disabled when the bandgap reference voltage has not reached a desired level. The power-on-reset circuitry may be sensitive or insensitive to the power-up sequence used by the power supply signals. Brownout detection blocking circuitry may be provided to prevent the output from one of the trip point detectors from influencing the power-on-reset circuitry.