Nanopower Boost Regulator Startup Circuit for Ultra-Low Voltage
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Solution Overview
Problem
Energy harvesting systems, such as those using photovoltaic cells, face challenges in starting up from ultra-low-voltage ranges (0.3V-0.5V) due to the threshold voltage requirements of devices being higher than the available voltage, leading to issues with leakage currents and the need for special processes to avoid them.
Innovation Solution
A nanopower boost regulator startup circuit is developed using an asynchronous boost circuit with stacked power NMOS transistors, a ring oscillator, and charge pumps, which generates a boosted voltage without requiring external components or special processes, enabling startup from 0V to 5V.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional boost regulator startup circuits are used, then device can operate normally, but external components or special processes are required to overcome threshold voltage limitations
Solution Approach 1:
The circuit uses stacked power NMOS transistors where the gate of each transistor is driven by the drain of the transistor below it, creating a self-bootstrapping mechanism that generates progressively higher voltages from the ultra-low input voltage without external assistance
Solution Approach 2:
The patent transitions from a single-voltage-level conventional startup approach to a multi-stage voltage boosting approach by stacking transistors in series, effectively adding a dimensional aspect of voltage multiplication through the stacked configuration
2Ease of manufacture
If standard NMOS transistors are used, then device is easier to manufacture, but leakage current increases at ultra-low-voltage
Solution Approach 1:
The patent changes the operating parameters by using stacked transistor configuration that modifies the voltage distribution across each transistor, allowing standard NMOS devices to operate in a regime where leakage is minimized while still achieving the required voltage multiplication
Solution Approach 2:
The stacked transistor structure performs preliminary voltage boosting action before the main circuit operation begins, ensuring that each transistor is properly biased and threshold voltage requirements are met before normal operation starts
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 allows for reliable startup from ultra-low-voltage ranges without external components or special processes, effectively addressing the challenge of powering devices with low input voltages in energy harvesting applications.
Implementation Method 1
a first charge pump that is driven by a clock output of the ring oscillator and that outputs a boosted voltage
Implementation Method 2
a ring oscillator that is powered by a power supply
Implementation Method 3
an asynchronous boost circuit to charge up an output with stacked power NMOS transistors
Data Source
AI summary
At least one embodiment provides a method for a nanopower boost regulator to startup from an ultra-low-voltage (such as 0.3V˜0.5V) for energy harvesting applications. The method does not necessarily require a special process or any external components such as mechanical switches. The startup circuit can include an asynchronous boost circuit to charge up an output with stacked power NMOS transistors, a ring oscillator, and/or a charge pump, along with accompanying circuitry.