Nano-Power Brown-Out Detector Circuit Design
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Solution Overview
Problem
Conventional brown-out detector (BOD) circuits consume high DC current and face challenges in scaling with decreasing supply voltages, particularly due to the difficulty in scaling the Zener diode reference voltage.
Innovation Solution
The implementation of a nano-power BOD circuit with multiple stages, including a bias generation stage, a single-ended to differential up-converter stage, and a gain stage, which uses power gating and temperature-independent current sources to reduce current consumption, and employs thick-gate transistors and un-salicided poly resistors to minimize leakage and process variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional BOD circuits use Zener diode reference voltage for comparison, then the brown-out detection function is achieved, but the DC current consumption becomes high (100 μA to over 1 mA)
Solution Approach 1:
The patent extracts and removes the Zener diode reference voltage circuit from the BOD design, replacing it with an on-chip bandgap reference voltage circuit. This extraction eliminates the high current consumption associated with Zener diodes while retaining the essential brown-out detection function through the bandgap reference.
Solution Approach 2:
The patent substitutes the external Zener diode component with an integrated on-chip bandgap reference voltage circuit. This substitution transitions from a discrete component-based approach to an integrated circuit approach, achieving both function and low power consumption.
2Productivity
If supply voltage scales down to enable higher integration, then device density improves, but the Zener diode reference voltage becomes more difficult to scale
Solution Approach 1:
The patent creates an on-chip copy of the reference voltage generation function using a bandgap circuit that can be integrated directly on the supply voltage chip. This copying of the reference function to the same chip enables scaling with supply voltage while maintaining detection accuracy.
Solution Approach 2:
The patent changes the reference voltage generation mechanism from Zener diode breakdown voltage to bandgap voltage, which has different scaling characteristics that are more compatible with scaled-down supply voltages and higher integration densities.
3Ease of manufacture
If external Zener diode is used for reference voltage, then the circuit implementation is simple, but the current consumption is high and scaling is difficult
Solution Approach 1:
The patent merges the reference voltage generation function with the supply voltage chip by integrating the bandgap circuit on-chip. This merging eliminates the need for external Zener diodes and their associated high current consumption paths.
Solution Approach 2:
The patent extracts the reference voltage generation function from external discrete components and relocates it to an integrated on-chip bandgap circuit, eliminating the high current consumption of external Zener diodes.
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 nano-power BOD circuit achieves significantly lower power consumption, with current draw reduced to nano-ampere ranges, and provides a reliable error signal for power management, enabling early warning of low power levels and preventing memory corruption.
Implementation Method 1
first transistors and first resistors arranged to receive an input voltage and provide an internal voltage that is substantially independent of temperature
Implementation Method 2
second transistors arranged to receive the input voltage and receive the internal voltage from the first stage, up-convert the internal voltage as the input voltage lowers
Implementation Method 3
third transistors arranged to receive the differential voltage and provide a high-gain output voltage corresponding to an error signal
Implementation Method 4
employs thick-gate transistors and un-salicided poly resistors to minimize leakage and process variation
Data Source
AI summary
Various implementations described herein are directed to an integrated circuit for brown-out detection. The integrated circuit may include a first stage configured to receive an input voltage and provide a first voltage independent of temperature while remaining related to the input voltage. The integrated circuit may include a second stage configured to receive the input voltage, receive the first voltage from the first stage, and up-convert the first voltage as input voltage lowers. The second stage may be configured to provide a second voltage corresponding to a differential voltage of the input voltage and the first voltage. The integrated circuit may include a third stage configured to receive the second voltage and provide a high-gain output voltage corresponding to an error signal.