Capacitor-Based BGR Start-Up Circuit for Wide Supply Operation

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Solution Overview

Problem

Conventional start-up circuits for NAND flash devices fail to simultaneously achieve zero steady-state current, dynamic behavior, and wide supply range operation, leading to inefficient power consumption and unreliable performance.

Innovation Solution

A capacitor action-based start-up circuit is introduced, comprising a start-up capacitor connected to a bandgap reference (BGR) sub-block and an output transistor that charges the BGR sub-block's slowest node during failure states to maintain normal operation, ensuring dynamic behavior and zero steady-state current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional start-up circuits are used in NAND flash devices, then the circuit can operate with supply voltage, but it cannot simultaneously achieve zero steady-state current, dynamic behavior, and wide supply range operation

Engineering Contradiction:

Improveoperational reliabilityVSAvoidsteady-state current

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The start-up capacitor C_ST is pre-charged to a first voltage level before BGR operation. During failure recovery, this pre-charged capacitor provides the necessary charge to the slowest node NB, enabling the BGR circuit to recover without requiring continuous steady-state current. The preliminary charging action eliminates the need for persistent current draw while maintaining operational reliability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The start-up circuit operates periodically rather than continuously. The capacitor C_ST charges during normal operation and discharges during failure recovery events. This periodic action pattern allows the circuit to maintain reliability only when needed while achieving zero steady-state current during normal standby conditions.

Inventive Principle:

Principle #19Periodic action

2Reliability

If conventional start-up circuits are used, then the circuit can maintain operation, but it lacks dynamic behavior to recover from failure states

Engineering Contradiction:

Improvefailure recovery capabilityVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The start-up capacitor C_ST acts as an intermediary energy storage element between the power supply and the BGR circuit nodes. It mediates the transfer of charge during failure recovery events, enabling dynamic behavior without requiring complex active circuitry. The capacitor serves as a simple yet effective mediator that provides the necessary charge to restore normal operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The circuit utilizes voltage parameter changes to indicate and respond to failure states. When the BGR circuit experiences a failure, the voltage at the slowest node NB changes, which triggers the start-up circuit to activate. The capacitor C_ST then provides charge to restore the voltage parameter to its normal operating range, enabling failure recovery through parameter monitoring and adjustment.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If the BGR sub-block operates with varying input voltages, then it can adapt to different supply conditions, but it requires complex voltage regulation

Engineering Contradiction:

Improvesupply range operationVSAvoidvoltage regulation complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The BGR circuit with the start-up capacitor is designed to be self-regulating within a wide supply voltage range. The capacitor C_ST automatically provides the necessary charge to the slowest node NB when voltage deviations occur, without requiring external voltage regulation circuitry. The circuit serves itself by using the capacitor's stored energy to correct voltage variations, enabling adaptability to different supply conditions while maintaining simplicity.

Inventive Principle:

Principle #25Self-service

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

The solution enables efficient power management by dynamically adjusting reference voltages and currents, ensuring reliable operation across a wide voltage supply range with zero steady-state current draw, thereby enhancing the performance and efficiency of NAND flash devices.

Implementation Method 1

a start-up capacitor (CST) connected to a VBG node of a BGR sub-block, wherein the start-up capacitor (CST) determines if a state of operation of the BGR sub-block is one of normal, and failure

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

an output transistor (MO) connected to an NB node of the BGR, wherein the output transistor (MO) charges the NB node to maintain normal operation of the BGR sub-block

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS20240331787A1Start-up circuit for bandgap references in a NAND flash

Publication Date: 2024.10.03 SAMSUNG ELECTRONICS CO LTD

AI summary

Various example embodiments relate to a capacitor action-based start-up circuit for bandgap reference (BGR) generation. The start-up circuit comprises a start-up capacitor connected to a VBG node of a BGR sub-circuit. The start-up capacitor determines if a state of operation of the BGR sub-block is one of normal, and failure. The start-up circuit comprises an output transistor connected to an NB node of the BGR. The output transistor charges the NB node to maintain normal operation of the BGR sub-block, if the state of operation of the BGR sub-block is failure, thereby facilitating dynamic behavior.