Automatic Gain Control Circuit with Background LNA Calibration

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Solution Overview

Problem

Conventional automatic gain control circuits for RF receivers fail to respond promptly to unwanted signals during non-preamble time regions, leading to inadequate gain adjustment for incoming packets, as they can only adjust the LNA gain during the preamble time region.

Innovation Solution

An automatic gain control circuit that performs background calibration in the non-preamble time region of a packet to predetermine a gain adjustment for the LNA, allowing immediate adjustment when the next preamble arrives, utilizing a power detector and a second amplifier to maintain the output voltage within a predetermined range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the automatic gain control circuit adjusts the gain of the LNA by detecting the power level of RF signals in the preamble time region, then the gain can be adjusted within a pre-determined range suitable for digitization, but the circuit does not have sufficient time to respond to unwanted signals that occur during the non-preamble time region

Engineering Contradiction:

Improvepower level detection accuracyVSAvoidresponse time to unwanted signals

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs background calibration during the non-preamble time region of the current packet to pre-determine the gain adjustment before the next packet's preamble arrives. This preliminary action allows the LNA gain to be adjusted immediately when needed, eliminating the time delay associated with detecting and responding to unwanted signals during packet reception.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent extends the gain control operation from only the preamble time region to include the non-preamble time region through background calibration. This continuous calibration process ensures that the LNA gain is continuously optimized based on actual signal conditions, rather than being adjusted only once during the brief preamble period.

Inventive Principle:

Principle #20Continuity of useful action

2Device complexity

If the automatic gain control circuit only operates during the preamble time region, then the circuit structure remains simple, but the gain adjustment cannot be performed promptly during the non-preamble time region

Engineering Contradiction:

Improvecircuit structure complexityVSAvoidgain adjustment speed

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The background calibration performed during the non-preamble time region serves as a preliminary action that prepares the gain adjustment in advance. This allows the system to maintain simple circuit structure while achieving fast gain adjustment response when packets arrive, as the calibration work is completed beforehand during idle periods.

Inventive Principle:

Principle #10Preliminary action

3Duration of action of moving object

If the gain adjustment is delayed until the preamble time region, then the circuit has sufficient time to process the signal, but the signal quality deteriorates due to inadequate gain adjustment for unwanted signals

Engineering Contradiction:

Improvesignal processing timeVSAvoidsignal quality

Core Design Contradiction:

Duration of action of moving objectVSReliability

Solution Approach 1:

The patent implements continuous gain optimization by performing background calibration during the non-preamble time region and applying the calibration results during the preamble time region. This continuous process ensures that the LNA gain is always optimized for current signal conditions, improving signal quality without sacrificing processing time.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The background calibration process uses the power detector to measure the actual signal power level and provides feedback to the second amplifier to adjust its gain accordingly. This feedback mechanism ensures that the LNA gain is continuously optimized based on real-time signal conditions, improving signal quality while maintaining adequate processing time.

Inventive Principle:

Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables immediate and precise gain adjustment of the LNA during the next preamble time region, ensuring optimal signal quality and reducing the impact of unwanted signals by utilizing background calibration in the non-preamble time.

Implementation Method 1

a power detector coupled to the LNA to detect a power level of the RF signal outputted from the LNA and to output a voltage level representing the power level of the RF signal

Methodology Applied

Scientific EffectPower detection:

Implementation Method 2

a second amplifier coupled to the power detector to adjust the voltage level outputted from the power detector

Methodology Applied

Scientific EffectElectrical amplification:

Data Source

PatentUS10601386B2Automatic gain control circuit with background calibration

Publication Date: 2020.03.24 RAFAEL MICROELECTRONICS INC

AI summary

An automatic gain control circuit for controlling an LNA for inputting signals carrying packets, the automatic gain control circuit can perform a background calibration in the non-preamble time region of a first packet for pre-determining a gain adjustment to the LNA before the next preamble of a second packet arrives, so that the gain of the LNA can be adjusted immediately according to the pre-determined gain adjustment when the next preamble of the second packet arrives.