Reference Voltage Circuit Startup Transistor Control
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Solution Overview
Problem
Existing reference voltage generation circuits face startup failures and wasteful power consumption due to continuous current flow through resistors, leading to voltage fluctuations and inefficiencies.
Innovation Solution
A reference voltage generation circuit incorporating a startup circuit unit with a depletion MOS transistor, an enhancement MOS transistor, and another enhancement MOS transistor, where the third transistor has a lower on-resistance and is mirror-connected to a transistor generating the reference voltage, along with a constant current and voltage generation unit to manage current flow and voltage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a startup circuit unit is integrated with a reference voltage generation unit to ensure reliable startup, then startup reliability is improved, but wasteful power consumption occurs after circuit startup due to continuous current flow through resistors
Solution Approach 1:
The patent applies dynamics by making the startup circuit's current path controllable and switchable. The third transistor (N-channel enhancement MOS transistor) acts as a dynamic switch that changes the circuit's current flow characteristics based on operating conditions. During startup, the third transistor conducts to provide startup current; after startup, it turns off to eliminate wasteful continuous current flow, thus resolving the contradiction between startup reliability and power consumption.
Solution Approach 2:
The patent implements periodic action through the third transistor that periodically enables and disables the startup current path. The transistor is turned on during the startup period to ensure reliable voltage generation, then turned off during normal operation to prevent wasteful power consumption. This time-based control strategy allows the circuit to have different current flow characteristics at different operational stages.
2Stability of the object's composition
If a current flows continuously through a resistor to maintain circuit operation, then circuit stability is maintained, but voltage fluctuations occur due to external factors affecting the power supply voltage
Solution Approach 1:
The patent extracts the harmful continuous current flow through the resistor by introducing the third transistor to selectively block this current path after startup. The third transistor is positioned to interrupt the current flow that would otherwise continue through the resistor, thereby removing the source of voltage fluctuations caused by external power supply variations while maintaining circuit stability through the reference voltage generation unit's feedback mechanism.
Solution Approach 2:
The third transistor serves as an intermediary element between the power supply and the reference voltage generation unit. It mediates the current flow by allowing startup current during initialization but blocking continuous current during normal operation. This intermediary control prevents external power supply fluctuations from affecting the reference voltage output through the resistor path, thus maintaining voltage stability.
3Reliability
If a great current flows into the output terminal via a transistor to ensure startup, then startup is achieved, but electric power consumption increases as wasteful consumption in steady state
Solution Approach 1:
The patent uses dynamics by making the startup current path controllable through the third transistor. During startup, the third transistor is in the on-state, allowing great current to flow into the output terminal to achieve reliable voltage generation. After startup, the third transistor switches to the off-state, completely blocking the current path and eliminating wasteful power consumption in the steady state. This dynamic switching resolves the contradiction between startup current requirements and steady-state power consumption.
Data Source
AI summary
In a reference voltage generation circuit, a reference voltage generation unit 1 is configured to receive, as feedback, a voltage of an output terminal 3; a startup circuit unit 2 has a depletion MOS transistor TR1, and enhancement MOS transistors TR2, TR3; the MOS transistor TR1 has one end connected to a power source 4 and is formed as a constant current connection; the MOS transistor TR2 has one end connected to the power source 4 via a resistor RST, has an opposite end connected to the output terminal 3, and further has a gate connected to an opposite end of the MOS transistor TR1; and the MOS transistor TR3 has one end connected to the opposite end of the MOS transistor TR1, has an opposite end grounded, and further has a gate connected to the output terminal 3. The reference voltage generation circuit can reduce the occurrence of a wasteful current consumption after circuit startup.