Wide Supply Range Precision Startup Current Source Circuit

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Solution Overview

Problem

Existing bandgap reference voltage circuits face challenges in maintaining stable operation across wide supply voltage ranges without risking oxide damage, particularly in ensuring proper startup and minimizing power consumption and area requirements.

Innovation Solution

The development of a wide supply range precision startup current source circuit utilizing native transistors with threshold voltages near 0V, which allows for efficient current generation with minimal power consumption and improved supply stability, by using low-voltage nmos transistors and high-voltage native transistors in a self-biased configuration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a typical startup circuit is used to initialize the bandgap circuit, then the bandgap circuit can reach its desired final value, but the startup circuit requires a large resistor which increases area and continues to consume current even when off

Engineering Contradiction:

Improvebandgap circuit startup reliabilityVSAvoidstartup circuit area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent extracts the startup function from a traditional resistor-based startup circuit and implements it using a capacitor coupled with a high-voltage transistor. The capacitor is charged through a high-value resistor during startup, then discharged to generate the startup current, eliminating the need for a large permanent resistor in the circuit path.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The startup mechanism uses periodic charging and discharging of a capacitor to generate startup current. The capacitor charges during the startup phase and then discharges to provide the necessary startup current, creating a time-dependent periodic action that initializes the bandgap circuit without requiring continuous current flow.

Inventive Principle:

Principle #19Periodic action

2Reliability

If the startup current is made smaller than the bandgap circuit current to ensure proper operation, then a large resistor is required, but this increases both area and power consumption

Engineering Contradiction:

Improvestartup current controlVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The capacitor-based startup circuit operates periodically, charging during startup and then discharging to provide current pulses only when needed. This periodic operation eliminates continuous power consumption associated with resistor-based startup circuits, as the high-value resistor only draws minimal current during the charging phase.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The startup circuit transitions from a static resistor-based design to a dynamic capacitor-based design. The capacitor allows the circuit to store energy and release it dynamically, providing startup current on-demand rather than through continuous current flow, thereby reducing average power consumption.

Inventive Principle:

Principle #15Dynamics

3Reliability

If high supply voltage is used to ensure proper operation, then the bandgap circuit operates reliably, but oxide damage may occur

Engineering Contradiction:

Improveoperating stabilityVSAvoidoxide damage risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the voltage parameter by introducing a capacitor coupled with a high-voltage transistor that can withstand high voltages without oxide damage. The capacitor isolates the high-voltage stress from the sensitive bandgap circuitry, allowing the use of high supply voltages for reliable operation while protecting against oxide damage through proper device selection and circuit configuration.

Inventive Principle:

Principle #35Parameter changes

4Area of stationary object

If a simple startup circuit is used, then area is minimized, but the circuit cannot ensure proper initialization and avoid zero-current stable state

Engineering Contradiction:

Improvestartup circuit areaVSAvoidinitialization capability

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The capacitor serves as an intermediary element that mediates between the power supply and the bandgap circuit during startup. It accumulates charge from the power supply through a high-value resistor and then releases this energy to generate the necessary startup current, enabling proper initialization without requiring a complex resistor-based startup circuit.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10261537B2Wide supply range precision startup current source

Publication Date: 2019.04.16 AVNERA CORP

AI summary

A start-up circuit for a bandgap reference voltage generator circuit, including a first native transistor with a drain connected to a supply voltage of the bandgap reference voltage generator circuit and a source connected to a gate of the first native transistor; a low voltage transistor with a source connected to ground, a drain connected to the source of the first native transistor, and a gate connected to a resistor; a second native transistor with a source connected to the resistor, a gate connected to the source of the first native transistor; a high voltage transistor with a drain connected to a drain of the second native transistor and a source connected to the supply voltage; and a transistor with a gate connected to the gate of the first high voltage transistor and a drain which provides a start-up current for the bandgap reference voltage generator circuit.