Bandgap Reference Circuit Pre-Charging for Fast Overshoot-Free Startup
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Solution Overview
Problem
Conventional bandgap reference circuits face challenges in achieving overshoot-free fast start-up under varying PVT conditions, affecting the startup speed and power efficiency of electronic devices.
Innovation Solution
A bandgap reference circuit design incorporating a bias current generation unit with a self-biased cascode current mirror structure and resistors with different temperature coefficients, generating a bias current independent of power supply voltage and temperature, enabling an overshoot-free fast start-up through pre-charge current management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional bandgap reference circuits are used, then the circuit can operate normally, but the startup time is long and power consumption is high
Solution Approach 1:
The patent applies preliminary action by introducing a pre-charge circuit that charges capacitors before the main circuit operation. The pre-charge circuit activates first to establish initial voltages on capacitors C1 and C2, enabling the bandgap reference circuit to start up quickly without requiring lengthy charging periods during normal operation. This preliminary charging action directly reduces both startup time and overall power consumption.
Solution Approach 2:
The patent implements dynamics by using a dynamic startup control mechanism that activates the pre-charge circuit only during startup phase. The circuit transitions from a high-power pre-charge state to a low-power normal operation state, dynamically adjusting power consumption based on operational requirements. This dynamic approach optimizes the balance between startup speed and power efficiency.
2Speed
If the bandgap reference circuit starts up quickly, then startup speed is improved, but voltage overshoot occurs during startup
Solution Approach 1:
The patent applies feedback by implementing a voltage detection mechanism that monitors the output voltage during startup. When the voltage reaches the target level, the feedback signal automatically disables the pre-charge circuit, preventing further charging that would cause overshoot. This closed-loop feedback control ensures rapid startup while maintaining voltage stability and preventing overshoot conditions.
Solution Approach 2:
The pre-charge circuit performs preliminary voltage establishment on capacitors before the main regulation phase begins. By pre-charging capacitors C1 and C2 to appropriate voltage levels, the circuit avoids the need for aggressive charging during normal startup, thereby reducing overshoot risk while maintaining fast startup performance.
3Adaptability or versatility
If the circuit operates under varying PVT conditions, then adaptability is improved, but startup performance becomes unpredictable
Solution Approach 1:
The patent applies parameter changes by designing the pre-charge circuit with adjustable charging currents that can adapt to different PVT conditions. The circuit modifies charging parameters based on process variations, voltage levels, and temperature conditions to ensure consistent startup performance across all operating environments. This parameter adaptation maintains reliable startup characteristics despite PVT variations.
Solution Approach 2:
The pre-charge circuit performs preliminary voltage establishment that compensates for PVT variations. By pre-charging capacitors with adjusted current levels based on detected PVT conditions, the circuit ensures that subsequent operation begins from a consistent voltage state, making startup performance predictable and reliable across different process, voltage, and temperature conditions.
Data Source
AI summary
An overshoot-free fast start-up bandgap reference circuit (100), a chip, and an electronic device. The bandgap reference circuit (100) comprises a bias current generating unit (101) and a reference core unit (102), wherein an output end of the bias current generating unit (101) is connected to an input end of the reference core unit (102), the bias current generating unit (101) generates a bias current (IBIAS) unrelated to the voltage of a power supply and having a zero temperature coefficient, the bias current (IBIAS) is an input signal of the reference core unit (102), and the reference core unit (102) generates a pre-charging current on the basis of the input bias current (IBIAS) and implements overshoot-free fast start-up by means of employing pre-charging.