MOS Startup Circuit With Gate Feedback for Stable Starting Current
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Solution Overview
Problem
Starting circuits using N-type MOS transistors with threshold voltage near 0 V face challenges in maintaining consistent drain current due to variations in threshold voltage, affecting device startup time and increasing current consumption.
Innovation Solution
A starting circuit design incorporating an N-type MOS transistor with a resistor between its source and ground, and a control circuit to manage the gate voltage, reducing the influence of threshold voltage variations by controlling the starting current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a Native-NMOS transistor with threshold voltage near 0 V is used in the starting circuit, then area and current consumption are reduced, but the drain current becomes sensitive to threshold voltage variations affecting starting time
Solution Approach 1:
The patent employs feedback mechanisms through carefully designed transistor connections where the drain current of the Native-NMOS transistor feeds back to control its own gate voltage. This self-regulating feedback loop compensates for threshold voltage variations, maintaining stable drain current and consistent starting time while preserving the low current consumption benefits of Native-NMOS transistors.
Solution Approach 2:
The patent utilizes parameter changes by operating the Native-NMOS transistor in specific voltage regions and adjusting gate voltages dynamically. By changing the operating parameters (gate voltage, drain voltage) in response to threshold voltage variations, the circuit maintains stable drain current characteristics, resolving the contradiction between low power consumption and starting time consistency.
2Reliability
If the gate voltage of the Native-NMOS transistor is increased to compensate for threshold voltage variation, then starting time consistency improves, but current consumption increases
Solution Approach 1:
The circuit implements self-service through automatic threshold voltage compensation mechanisms. The Native-NMOS transistor and associated circuitry automatically adjust gate voltages in response to threshold voltage variations without external intervention. This self-regulating process maintains starting time consistency while avoiding the need for external voltage sources that would increase current consumption.
Solution Approach 2:
The feedback mechanism dynamically adjusts the gate voltage of the Native-NMOS transistor based on the actual drain current and threshold voltage conditions. This closed-loop control ensures starting time consistency is maintained while optimizing current consumption by applying voltage adjustments only when and where needed, rather than continuously increasing voltage.
Data Source
AI summary
A starting circuit capable of further reducing an influence of a variation in the threshold voltage of a transistor is proposed. The starting circuit includes an N-type first MOS transistor whose threshold voltage is near 0 V, a resistor interposed between a source terminal of the first MOS transistor and a ground, and a control circuit controlling a gate voltage of the first MOS transistor. An amount of first current transmitted to a device to be driven and starting the device is controlled according to the control of the gate voltage.