Bandgap Reference Voltage Startup Circuit with Dual Pull-Up and Pull-Down Mechanisms

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Solution Overview

Problem

Bandgap reference voltage generation circuits in semiconductor systems face challenges in startup operations, particularly when power supply voltage is delayed or operating temperature is low, leading to failed startup due to insufficient voltage differences and increased leakage currents.

Innovation Solution

Incorporating a dual startup circuit approach, comprising a pull-up first startup circuit and a pull-down second startup circuit, which work together to ensure stable bandgap reference voltage generation by amplifying differential voltages and managing power supply and ground voltages effectively, even in environments with high leakage currents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a pull-down startup circuit is used to create sufficient voltage difference for OP amplifier startup, then the startup reliability is improved, but the circuit cannot handle high leakage current conditions effectively

Engineering Contradiction:

Improvestartup reliabilityVSAvoidleakage current sensitivity

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The startup circuit is divided into two separate functional circuits: a first startup circuit (pull-down type) that creates initial voltage difference for reliable OP amplifier startup, and a second startup circuit (pull-up type) that specifically counteracts leakage current effects. This segmentation allows each circuit to be optimized for its specific function without compromise.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

While conventional designs use only pull-down startup circuits, this invention introduces a pull-up startup circuit that operates in the opposite direction. The second startup circuit pulls up the second node voltage, counteracting the voltage drop caused by leakage currents, thereby enabling startup under high leakage current conditions where traditional pull-down circuits fail.

Inventive Principle:

Principle #13The other way round (Inversion)

2Device complexity

If the bandgap reference voltage generation circuit is integrated with other electrical elements in an IC, then the system complexity is reduced, but the startup operation becomes more difficult under varying temperature and leakage conditions

Engineering Contradiction:

Improvesystem integrationVSAvoidstartup operation stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The dual startup circuits are designed to activate automatically at power-on before the main bandgap reference circuit begins operation. The first startup circuit establishes the initial voltage difference, and the second startup circuit compensates for leakage effects, ensuring the OP amplifier is properly biased before normal operation commences. This preliminary action ensures reliable startup despite integration challenges.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If a single startup circuit is used to simplify the circuit design, then the device complexity is reduced, but the startup performance under high leakage current conditions deteriorates

Engineering Contradiction:

Improvecircuit design simplicityVSAvoidstartup performance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

Rather than using a single complex startup circuit, the invention segments the startup function into two simpler, dedicated circuits. The first startup circuit handles the basic voltage difference creation, while the second startup circuit specifically addresses leakage current compensation. This segmentation achieves both simplicity and high reliability under varying conditions.

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This dual startup circuit configuration enables normal startup operations and maintains high-speed ramp-up characteristics, ensuring stable reference voltage generation despite increased leakage currents and temperature variations.

Implementation Method 1

an OP amplifier to amplify a differential voltage between a first node and a second node

Methodology Applied

Scientific EffectDifferential voltage amplification:

Implementation Method 2

a first startup circuit which receives input of an output signal of the OP amplifier from an output voltage node of the bandgap reference voltage generation circuit and pulls up the second node

Methodology Applied

Scientific EffectVoltage level shifting:

Implementation Method 3

a second startup circuit which pulls down the output voltage node

Methodology Applied

Scientific EffectVoltage level resetting:

Data Source

PatentUS10712762B2Semiconductor circuit and semiconductor system

Publication Date: 2020.07.14 SAMSUNG ELECTRONICS CO LTD

AI summary

Provided are a semiconductor circuit and a semiconductor system. A semiconductor circuit includes a bandgap reference voltage generation circuit including an operational amplifier to amplify a differential voltage between a first node and a second node; a first startup circuit which receives input of an output signal of the operational amplifier from an output voltage node of the bandgap reference voltage generation circuit and pulls up the second node; and a second startup circuit which pulls down the output voltage node.