State-Machine AGC Feedback for Stable Wireless Gain Lock

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Solution Overview

Problem

Existing automatic gain control (AGC) circuits in IEEE 802 wireless systems face instability due to unpredictable feedback timing in pulse-based transmit/receive systems, where the time, length of packet, and signal strength are unknown until transmission occurs, leading to unstable gain adjustments.

Innovation Solution

An AGC circuit with a state machine controller that provides feedback to baseband demodulators to optimize filter timing and gain adjustments, allowing for precise prediction of system delays and conditions, thereby stabilizing the gain control process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the AGC provides feedback quickly to lock in on the signal, then the response speed is improved, but the feedback timing becomes unpredictable causing instability

Engineering Contradiction:

Improveresponse speedVSAvoidgain control stability

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The state machine controller predicts system delays and prepares gain adjustments in advance based on expected signal conditions. By performing preliminary actions to compensate for known delay periods, the system achieves both fast response and stable control, resolving the contradiction between speed and stability.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If the AGC makes frequent gain adjustments to track signal changes, then the adaptability is improved, but the oscillations increase reducing reliability

Engineering Contradiction:

Improvesignal tracking adaptabilityVSAvoidsystem reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The state machine controller dynamically adjusts the demodulator's filter timing and gain settings based on real-time signal conditions and predicted delays. This dynamic adaptation allows the system to track signal changes effectively while maintaining stability by coordinating adjustments with the signal structure, thus improving adaptability without increasing oscillations.

Inventive Principle:

Principle #15Dynamics

3Productivity

If the demodulator operates quickly to recover data in pulse-based systems, then the productivity is improved, but the timing precision deteriorates

Engineering Contradiction:

Improvedata recovery speedVSAvoidtiming precision

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The state machine controller provides feedback information about predicted delays and signal conditions to the demodulator. This feedback enables the demodulator to operate quickly while maintaining precise timing by adjusting its operations based on the predicted delay information, thus achieving both high productivity and timing precision.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP2229727B1Automatic gain control with state machine controller feedback

Publication Date: 2012.12.19 THOMSON LICENSING SA

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AI summary

An automatic gain control circuit is described including a state machine controller for adjusting intermediate frequency gain and radio frequency gain and a baseband demodulator, wherein the baseband demodulator receives information from the state machine controller regarding status of the state machine controller and further wherein the state machine controller receives correlation information from the baseband demodulator. Also described is a method including detecting a signal, providing state machine controller information to a baseband demodulator, reducing a radio frequency gain, reducing an intermediate frequency gain and receiving correlation information from the baseband demodulator.