Bandgap Voltage Reference Circuit Flipped Voltage Follower
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Solution Overview
Problem
Conventional bandgap voltage reference circuits have slower starting speeds and insufficient driving ability, limiting their application in VLSI systems due to their two-stage amplifying circuit framework and insufficient frequency compensation.
Innovation Solution
A bandgap voltage reference circuit incorporating a bandgap current generating circuit, a differential pair circuit, and a flipped voltage follower, where the flipped voltage follower increases the frequency response and driving ability by reducing equivalent capacitance, allowing for faster startup and improved output driving capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-stage amplifying circuit framework is used, then the circuit provides stable reference voltage, but the starting speed becomes slower
Solution Approach 1:
The circuit is divided into distinct functional modules: a first amplifying circuit for voltage amplification, a second amplifying circuit for additional gain, and a flipping voltage follower for impedance transformation. This segmentation allows each module to be optimized independently, enabling faster startup while maintaining stable reference voltage output.
Solution Approach 2:
The patent employs a flipping voltage follower configuration that inverts the traditional voltage follower approach. This inversion provides higher output impedance and faster response characteristics, resolving the contradiction between stability and startup speed by reversing the conventional architecture.
2Reliability
If a two-stage amplifying circuit framework is used, then the circuit provides stable reference voltage, but the driving ability becomes insufficient
Solution Approach 1:
The patent combines multiple amplifying circuits with different characteristics - a first amplifying circuit for stability, a second amplifying circuit for gain enhancement, and a flipping voltage follower for impedance matching. This merging of complementary circuit functions simultaneously improves driving ability while maintaining reference voltage stability.
Solution Approach 2:
The circuit architecture functions as a composite structure where different circuit blocks (amplifying circuits and voltage follower) with complementary characteristics are integrated. This composite approach enables the output stage to deliver both stable voltage and sufficient driving current capability.
3Reliability
If Miller capacitor is used for frequency compensation, then the circuit achieves stability, but the starting speed becomes slower
Solution Approach 1:
The patent extracts or removes the traditional Miller capacitor compensation approach and replaces it with a flipping voltage follower configuration. This extraction eliminates the speed-limiting effect of the Miller capacitor while maintaining circuit stability through the alternative flipping follower architecture.
Solution Approach 2:
The patent changes the frequency compensation parameter from a Miller capacitor-based approach to a flipping voltage follower-based approach. This parameter change fundamentally alters the frequency response characteristics, achieving both stability and faster startup speed simultaneously.
Data Source
AI summary
A bandgap voltage reference circuit configured to generate a bandgap reference voltage is provided. The bandgap voltage reference circuit includes a bandgap current generating circuit, a differential pair circuit and a flipped voltage follower. The bandgap current generating circuit converts the bandgap reference voltage into a bandgap current and generates a first voltage and a second voltage according to the bandgap current. The differential pair circuit is coupled to the bandgap current generating circuit to receive the first voltage and the second voltage and configured to reduce a voltage difference between the first voltage and the second voltage and generate a third voltage. The flipped voltage follower is coupled to the differential pair circuit to receive the third voltage and generates the bandgap reference voltage accordingly.