Floating Reference Buffer Circuit for Fast High-Voltage Startup
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Solution Overview
Problem
Existing circuit designs for high-voltage applications face challenges in providing a stable floating reference signal during startup, as bandgap circuits used for generating accurate references are slow to turn on, leading to potential transistor overstress.
Innovation Solution
A buffer circuit utilizing an operational amplifier with two non-inverting inputs and an inverting input, configured as a voltage follower, provides either the first or second input signal as the floating reference signal, allowing for quicker startup and control of transistors in high-voltage domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a bandgap circuit is used to generate a precise floating reference signal, then the reference signal accuracy is improved, but the startup time increases due to slow turn-on
Solution Approach 1:
The patent applies preliminary action by introducing a startup circuit that generates a temporary reference signal before the bandgap circuit is fully operational. This startup reference signal is provided in advance to ensure transistors can be properly controlled during the period when the main bandgap reference is still settling, thereby resolving the contradiction between accuracy and startup speed.
2Measurement precision
If a bandgap circuit operates on a low-voltage circuit with current mirror and matching resistors, then the reference signal precision is improved, but the circuit complexity increases
Solution Approach 1:
The patent extracts the startup reference signal generation function from the main bandgap circuit by implementing a separate startup circuit. This separation allows the bandgap circuit to focus on providing accurate reference signals while the startup circuit handles the temporary reference generation, thereby reducing the overall circuit complexity while maintaining precision.
3Use of energy by moving object
If a low-dropout LDO circuit is employed to reduce bandgap power consumption, then the power efficiency is improved, but a chicken and egg problem occurs during power-up
Solution Approach 1:
The patent resolves the chicken and egg problem by implementing preliminary action through a startup circuit that generates the initial reference signal before the LDO and bandgap circuit are fully operational. This allows the LDO to start up without requiring a reference signal from the bandgap, eliminating the circular dependency while maintaining power efficiency.
Data Source
AI summary
Buffer circuit for providing a floating reference signal, voltage generating circuit and method for providing a floating reference signalIn one embodiment a buffer circuit for providing a floating reference signal comprises an operational amplifier comprising a first input, a second input, a third input and an output. The first input represents a non-inverting input and is configured to receive a first input signal. The second input represents another non-inverting input and is configured to receive a second input signal. The third input represents an inverting input. The output forms an output of the buffer circuit. The operational amplifier is configured as a voltage follower. The buffer circuit is configured to provide either the first or the second input signal at its output, such that a lower one of the first and the second input signal is provided as the floating reference signal.