Feed-Forward Amplifier Circuit for Fast Stable Gain Control

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Solution Overview

Problem

Existing amplifier systems face issues with slow and unstable gain feedback control, limited bandwidth, and susceptibility to interference, as well as overlooking important signal parameters beyond amplitude and phase due to reliance on closed-loop feedback control circuits.

Innovation Solution

Implementing a feed-forward control circuit that analyzes input signals to generate control signals that modify amplifier characteristics or physical aspects, such as power level, frequency, and spectral content, to optimize output signal quality independently of feedback loops.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If feedback control circuit is used to maintain amplifier gain, then gain stability is improved, but control loop speed and stability deteriorate

Engineering Contradiction:

Improvegain stabilityVSAvoidcontrol loop speed

Core Design Contradiction:

Stability of the object's compositionVSSpeed

Solution Approach 1:

The patent inverts the conventional feedback approach by using feed-forward control. Instead of monitoring output and adjusting input (feedback), the system analyzes the input signal and pre-adjusts amplifier characteristics before the signal passes through. This inversion eliminates the control loop delay inherent in feedback systems, achieving both gain stability and fast response.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The feed-forward control circuit performs preliminary analysis of the input signal characteristics (amplitude, frequency, spectral content) and generates appropriate control signals before the signal is amplified. This preliminary action allows the amplifier to be pre-configured for optimal performance, avoiding the latency of feedback-based adjustment.

Inventive Principle:

Principle #10Preliminary action

2Stability of the object's composition

If closed loop feedback operation is used, then gain control is improved, but device size and power consumption increase

Engineering Contradiction:

Improvegain controlVSAvoiddevice size

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent extracts the control function from the feedback loop and places it in a separate feed-forward control circuit that operates independently. This separation allows for a more compact design by eliminating the need for complex feedback path components while maintaining effective gain control through input signal analysis.

Inventive Principle:

Principle #2Taking out (Extraction)

3Stability of the object's composition

If closed loop feedback operation is used, then gain control is improved, but bandwidth and interference susceptibility deteriorate

Engineering Contradiction:

Improvegain controlVSAvoidbandwidth

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

By inverting the control approach from feedback to feed-forward, the system avoids the bandwidth limitations imposed by feedback loop stability requirements. The feed-forward controller can operate across a wider frequency range without the phase margin constraints that limit feedback systems.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS11929718B2Systems and methods for optimizing amplifier operations

Publication Date: 2024.03.12 PSEMI CORP

AI summary

Methods and systems for optimizing amplifier operations are described. The described methods and systems particularly describe a feed-forward control circuit that may also be used as a feed-back control circuit in certain applications. The feed-forward control circuit provides a control signal that may be used to configure an amplifier in a variety of ways.