AGC Gain Step Tracking for Stable Wireless Receiver Switching

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Solution Overview

Problem

Existing wireless receivers face performance degradation due to uncertainty in analog gain step magnitudes caused by component mismatches and temperature variations, leading to unnecessary switching, saturation, and reduced signal-to-quantization ratio, which cannot be effectively calibrated in advance.

Innovation Solution

A gain step magnitude tracking system that monitors the output from the automatic gain control circuit using a reference signal to adjust digital gain corrections dynamically, updating nominal gain step magnitudes with a first-order loop to compensate for actual gain changes, thereby eliminating the need for factory calibration and addressing temperature-induced uncertainties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If factory calibration is performed to compensate for component tolerances, then manufacturing precision is improved, but device complexity and cost increase due to individual calibration requirements

Engineering Contradiction:

Improvegain step magnitude accuracyVSAvoidcalibration process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system performs self-calibration by automatically tracking and adjusting gain step magnitudes using the received signal itself as the reference, eliminating the need for external calibration equipment and individual factory calibration processes for each device

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system performs preliminary gain calibration by establishing nominal gain step magnitudes before operation, then continuously tracks and corrects these values during normal operation to maintain accuracy without requiring repeated factory calibration

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If analog gain state switching is implemented to handle signal strength variations, then adaptability is improved, but reliability deteriorates due to unnecessary switching caused by gain step magnitude uncertainty

Engineering Contradiction:

Improvesignal strength adaptationVSAvoidreceiver performance stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system implements feedback by continuously monitoring the AGC output signal level and comparing it against reference values, then using this feedback to track actual gain step magnitudes and adjust switching thresholds dynamically, preventing unnecessary gain state transitions

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system makes the gain switching thresholds dynamic by adjusting them based on tracked actual gain step magnitudes, allowing the switching behavior to adapt to temperature variations and component drift while maintaining stability and avoiding unnecessary transitions

Inventive Principle:

Principle #15Dynamics

3Device complexity

If nominal gain step magnitudes are used without tracking, then device complexity is reduced, but measurement precision deteriorates due to temperature variation and component mismatches

Engineering Contradiction:

Improvegain control system complexityVSAvoidgain step magnitude accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The system uses feedback from the AGC output signal to continuously track actual gain step magnitudes, comparing measured values against nominal values and correcting for drift due to temperature and component variations, maintaining precision without complex hardware

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system replaces complex hardware calibration mechanisms with a software-based tracking algorithm that uses digital signal processing to monitor and correct gain step magnitudes, reducing mechanical complexity while maintaining or improving measurement precision

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If hysteresis margins are increased to prevent unnecessary switching, then reliability is improved, but productivity deteriorates due to reduced switching responsiveness

Engineering Contradiction:

Improveswitching stabilityVSAvoidgain adjustment responsiveness

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system dynamically adjusts hysteresis margins based on tracked gain step magnitude accuracy and signal conditions, maintaining sufficient margins to prevent unnecessary switching while allowing rapid response when genuine signal changes occur, optimizing both reliability and responsiveness

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS7873340B2Method to track analog gain step magnitudes online during operation of wireless mobile devices

Publication Date: 2011.01.18 QUALCOMM INC

AI summary

Systems and methods are provided for tracking and compensating for analog gain mismatches or changes in a receiver. In an embodiment, a method is provided to track analog gain step magnitudes during operation of a device. The method includes employing an error signal between an automatic gain control (AGC) output and a reference level as input to a gain step magnitude tracking component. This also includes determining at least one compensation value from the AGC output to update a nominal gain step magnitude that tracks an actual gain step magnitude.