Amplification Stage Control Loop Using Delayed Feedback

Solution Overview

Problem

Conventional multi-loop control systems, particularly in modulated power supply stages, face challenges in managing high bandwidth and dynamic range requirements due to the presence of both low and high frequency signals, which burdens the combiner and demands extreme operational capabilities.

Innovation Solution

The introduction of a delay stage in the high frequency feedback loop, matching the delay of the low frequency path, reduces the low frequency content in the high frequency path, allowing AC coupling and minimizing the dynamic range requirements, thereby reducing the burden on the combiner.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the high frequency feedback loop operates over the full frequency range including low frequencies, then the control system can provide constant output across all frequencies, but the combiner must handle extremely high bandwidth and dynamic range requirements, operating on the edge of its capabilities

Engineering Contradiction:

Improveconstant output capabilityVSAvoidcombiner bandwidth requirement

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The control system is divided into two separate frequency domains: a low frequency path handling DC to low frequency signals, and a high frequency path handling only high frequency signals. This segmentation allows each path to be optimized for its specific frequency range, with the low frequency path providing constant output and the high frequency path providing error correction only where needed.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A delay stage is introduced as an intermediary element in the high frequency feedback loop. This delay stage matches the delay of the low frequency path, enabling AC coupling and allowing the high frequency loop to operate without low frequency components while maintaining proper phase relationships for error signal generation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If the delay stage matches the delay of the low frequency path, then low frequency error is removed from the high frequency path enabling AC coupling, but the high frequency loop can no longer provide constant output at low frequencies

Engineering Contradiction:

Improvecombiner burdenVSAvoidconstant output at low frequency

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The control system is divided into two separate frequency domains: a low frequency path handling DC to low frequency signals, and a high frequency path handling only high frequency signals. This segmentation allows each path to be optimized for its specific frequency range, with the low frequency path providing constant output and the high frequency path providing error correction only where needed.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The low frequency path provides feedback for constant output regulation, while the high frequency path provides feedback for error correction. The delay stage ensures proper phase alignment between the two feedback paths, allowing them to work together effectively without interfering with each other's frequency ranges.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS9356559B2Control loop for amplification stage

Publication Date: 2016.05.31 SNAPTRACK INC

AI summary

There is disclosed a method and apparatus for generating an output signal comprising a replica of an input signal, comprising the steps of: generating a replica signal representing the low frequency content of the input signal; generating an error signal representing an error in the replica signal; combining the replica signal with the error signal to generate an output signal; and wherein the step of generating the error signal further includes the steps of: generating a delay signal being a delayed version of the input signal; and determining a difference between the output signal and the delay signal which difference is the error signal.