Current-Controlled Current Source for Noise-Immune LED Regulation

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Solution Overview

Problem

Conventional regulator systems face noise susceptibility and erratic behavior due to differences in ground potentials, especially in high-power systems like white LED backlighting, where the sensitivity of regulated voltage to ground noise is high, leading to significant variations in output current.

Innovation Solution

The solution involves converting regulated voltage and reference voltage to current signals and using a current-controlled current source for linear operations, such as subtraction or addition, which improves noise immunity and allows for direct drive of loop filters and control functions, utilizing simple transistors like bipolar or MOS FETs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If voltage feedback and resistive voltage divider are used in conventional regulator systems, then voltage regulation can be achieved, but noise susceptibility increases and ground potential differences cause erratic behavior

Engineering Contradiction:

Improveregulator stabilityVSAvoidground noise susceptibility

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the conventional voltage-based feedback system with a current-based system. Current signals are used throughout the feedback loop instead of voltage signals, and current-controlled current sources replace voltage-controlled voltage sources. This substitution of the fundamental signal type eliminates the sensitivity to ground potential differences that plagues voltage-based systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental parameter used for feedback from voltage to current. By operating the entire feedback loop in the current domain rather than the voltage domain, the system achieves immunity to ground noise. The current-controlled current source maintains a constant output current regardless of ground potential variations, fundamentally changing how the regulation is performed.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If voltage feedback is used with high gain in high-power systems, then regulation precision can be achieved, but sensitivity to ground noise increases significantly

Engineering Contradiction:

Improvevoltage regulation precisionVSAvoidground noise sensitivity

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent substitutes voltage signals with current signals throughout the feedback path. The current-controlled current source uses current feedback instead of voltage feedback, and the error amplifier operates with current inputs and current outputs. This substitution eliminates the ground noise sensitivity that amplifies with voltage-based high-gain systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If conventional voltage-controlled voltage sources are used, then voltage regulation can be provided, but the system requires complex grounding references and becomes prone to erratic behavior

Engineering Contradiction:

Improveground reference requirementsVSAvoidsystem behavior consistency

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent replaces voltage-controlled voltage sources with current-controlled current sources. The CCCS uses current control signals instead of voltage control signals, and provides current output instead of voltage output. This fundamental substitution eliminates the need for precise ground references between different parts of the system, as current signals are less sensitive to ground potential differences.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS8581659B2Current controlled current source, and methods of controlling a current source and/or regulating a circuit

Publication Date: 2013.11.12 DB GLOBALCHIP CO LTD

AI summary

Current sources, systems including the current source, and methods for regulating and/or controlling a circuit using the current source. The current source is generally configured to (i) receive a reference current, a bias voltage and a feedback/input current and (ii) provide an output current. The systems generally include the current source, a circuit directly or indirectly receiving the output current, a bias source/generator configured to provide the bias voltage, and a current reference configured to sink or source a predetermined amount of current from or to the output current. The method generally includes (a) applying a bias voltage to the current source, the current source receiving an input current and providing an output current; (b) sinking or sourcing a reference current from or to the output current; (c) applying the output of the current source directly or indirectly to a regulated circuit; and (d) providing the input current from the regulated circuit.